wood is good - user oriented material, technology

Transcription

UNIVERSITY OF ZAGREB
FACULTY OF FORESTRY
INNOVAWOOD
24th International Scientific Conference
WOOD IS GOOD - USER ORIENTED MATERIAL,
TECHNOLOGY AND DESIGN
October 18th, 2013
ZAGREB, CROATIA
ORGANISERS
INNOVAWOOD
FACULTY OF FORESTRY ZAGREB
WOOD SCIENCE AND TECHNOLOGY DEPARTMENT, BIOTECHNICAL FACULTY,
LJUBLJANA UNIVERSITY
ZAGREB FAIR
CROATIAN FORESTRY SOCIETY
SLOVENIAN ASSOCIATION OF WOOD TECHNOLOGISTS
THE SCIENTIFIC COUNCIL FOR AGRICULTURE AND FORESTRY – CROATIAN ACADEMY OF
SCIENCES AND ARTS
CROATIAN ACADEMY OF ENGINEERING
ACADEMY OF FORESTRY
CROATIAN CHAMBER OF ENGINEERS OF FORESTRY AND WOOD TECHNOLOGY
SUPPORTED BY
MINISTRY OF AGRICULTURE
COCO-SPONSORSHIP
MINISTRY OF ENTREPRENEURSHIP AND CRAFTS
CROATIAN FOREST RESEARCH INSTITUTE
CROATIAN FORESTS d.o.o.
CROATIAN CHAMBER OF ECONOMY
CROATIAN CHAMBER OF ECONOMY - ZAGREB
ZAGREB COUNTY
VIROVITICA-PODRAVINA COUNTY
UNIVERSITY OF ZAGREB
FACULTY OF FORESTRY
INNOVAWOOD
ZAGREB FAIR
24th International Scientific Conference
WOOD IS GOOD – USER ORIENTED MATERIAL, TECHNOLOGY AND
DESIGN
PROCEEDINGS
Zagreb
Zagreb 18
18th of October 2013
2013
A CIP catalogue record for this book is available in the Online Catalogue of the National and University
Library
in Zagreb as 855287
Publisher:
Publisher:
FACULTY OF FORESTRY, ZAGREB UNIVERSITY
Organizers
Organizers:
ers:
INNOVAWOOD
FACULTY OF FORESTRY ZAGREB
WOOD SCIENCE AND TECHNOLOGY DEPARTMENT, BIOTECHNICAL FACULTY, LJUBLJANA UNIVERSITY
ZAGREB FAIR
CROATIAN FORESTRY SOCIETY
SLOVENIAN ASSOCIATION OF WOOD TECHNOLOGISTS
THE SCIENTIFIC COUNCIL FOR AGRICULTURE AND FORESTRY – CROATIAN ACADEMY OF SCIENCES AND ARTS
CROATIAN ACADEMY OF ENGINEERING
ACADEMY OF FORESTRY
Organizing
Organizing committee:
committee:
Professor Marian Babiak, PhD (Slovakia), Assistant Professor Christian Brischke, PhD (Germany), Mariano
Perez Campos, PhD (Spain), Damir Felak, BSc (Croatia), Professor Ivica Grbac, PhD (Croatia), Associated
Professor Miha Humar, PhD (Slovenia), Ivan Ištok, BSc (Croatia), Associated Professor Vassil Jivkov, PhD
(Bulgaria), Nada Banek, MSc (Croatia), Petar Jurjević, MSc (Croatia), Borut Kričej, univ. BSc (Slovenia),
Professor Trajče Manev, PhD (Macedonia), Associated Professor Assia Marinova, PhD (Bulgaria), Božica
Marković, BSc (Croatia), Academic Slavko Matić, PhD (Croatia), Professor Milan Oršanić, PhD (Croatia),
Professor Marko Petrič, PhD (Slovenia), Professor Jerzy Smardzewski, PhD (Poland), Milan Trbojević
(Croatia), Mr. Gus Verhaeghe, (Belgium), Nikica Šprem, PhD (Croatia), Professor Joris Van Acker
(Belgium), Dijana Vuletić, PhD (Croatia), Associated Professor Silvana Prekrat, PhD (Croatia), Professor
Stjepan Pervan, PhD (Croatia), Professor Vladimir Andročec (Croatia)
EditorEditor-inin-chief:
chief:
Professor Ivica Grbac, PhD
Assistants
Assistants to EditorEditor-inin-chief:
Professor Stjepan Pervan, PhD
Associate Professor Silvana Prekrat, PhD
Technical editor:
editor:
Miljenko Klarić, MEng in Wood Technology
Cover design:
Associate Professor Silvana Prekrat, PhD
Professor Stjepan Pervan, PhD
Miljenko Klarić, MEng in Wood Technology
Programme
Programme committee and reviewers:
Professor Andrija Bogner, PhD (Croatia), Professor Stanislaw Dziegielewski, PhD (Poland), Professor Ivica
Grbac, PhD (Croatia), Professor Vladimir Jambreković, PhD (Croatia), Professor Vlatka Jirouš-Rajković, PhD
(Croatia), Associated Professor Vassil Jivkov, PhD (Bulgaria), Professor Boris Ljuljka, PhD (Croatia), Professor
Marko Petrič, PhD (Slovenia), Professor Andreas Rapp, PhD (Germany), Professor Milan Šernek, PhD
(Slovenia), Associated Professor Silvana Prekrat, PhD (Croatia), Professor Stjepan Pervan, PhD (Croatia)
EDITION
200 copies
ISBN: 978-953-292-031-4
FOREWORD
Although the profit and how it will be provided will stay in this time of crisis one of
main topics, this year’s conference “WOOD IS GOOD – USER ORIENTED MATERIAL,
TECHNOLOGY AND DESIGN” draws attention to the end user as a vital participant in
creating profitable products. Attention is still focused on to the still large number of
products that are focused only on profit, which in long term will cause loss to the society.
Creative potentials are opened for new insights and innovative processes, whose
primary goal is adjustment to the customer and environment, and their main task has to
be a conscious conservation of the environment and natural resources. These are the
preconditions for the increase of competitiveness and flexibility of all industrial branches
in both the world and the Croatian wood processing industries.
Proceedings of this conference is a great source of answers to questions about the
new achievements in the field of design, construction, economics, ergonomics, wood and
non-wood materials and their properties. Papers in proceedings are outcome studies of
domestic and foreign experts in wood technology, economics, ergonomics and design,
who wanted to draw attention to the end user and their needs in the design, selection of
materials and technologies of designed products.
The concept of sustainable development as the vital concept of the economic
development strategy of modern Europe and the European Union is based on creating a
competitive market of knowledge, research processes and experiences. This concept aims
at better social relations, prevention of effects of serious climate changes, preservation of
nature and creation of healthy environment.
By accessing to the European Union, in this year the Croatian forestry and wood
processing sector in cooperation with INNOVAWOOD organisation will be connected
with countries that have experience of designing and manufacturing products based on
meaningful synergy interdisciplinary work of various experts focused on users without
neglecting the profit as the basis for market survival.
Joining the European Union this year will provide new possibilities to Croatian
forestry and wood processing sectors for a better development in the future
Professor Ivica Grbac, PhD
CONTENTS
1. BARBOUTIS Ioannis – KAMPERIDOU Vasiliki:
KLISMOS - THE STYLE AND FORM OF THE ANCIENT GREEK CHAIR
1
2. DOMLJAN Danijela – VLAOVIĆ Zoran – ŽUPČIĆ Ivica – ŽIVKOVIĆ Vjekoslav –
JIROUŠ-RAJKOVIĆ Vlatka – GRBAC Ivica:
QUALITY OF THE WOODEN PRODUCTS FOR DESIGN AND EQUIPPING
EDUCATIONAL INSTITUTIONS
9
3. ESEN Raşit – YAPICI Fatih:
THE EFFECTS OF PRESS TIME AND PRESS PRESSURE ON THE SCREW STRENGTH
PROPERTIES OF ORIENTED STRENGTH BOARD (OSB) MANUFACTURED FROM
POPLAR WOOD
15
4. FABISIAK Beata – KŁOS Robert – MAĆKOWIAK Katarzyna:
ANALYSIS OF USER PREFERENCES CONCERNING E-TREND IN KITCHEN
FURNITURE DESIGN
19
5. GORNIK BUČAR Dominika – MERHAR Miran – GOSPODARIČ Bojan:
INFLUENCE OF TOOL WEAR ON THE QUALITY OF THE NEWLY FORMED
SURFACE IN THE DRILLING OF WOOD COMPOSITES
29
6. GRLADINOVIĆ Tomislav – PERIĆ Ivana – STASIAK-BETLEJEWSKA Renata –
ŠKODA Petar::
INCREASING THE PRODUCTIVITY OF ENTERPRISES WITH THE 20 KEYS METHOD
35
7. HROVATIN Jasna – VIŽINTIN Jože:
KITCHEN FURNITURE - ACCESSIBILITY OF STORAGE AND WORKING SPACE
41
8. JIVKOV Vassil – SIMEONOVA Ralitsa – MARINOVA Assia – GRADESVA Galina:
STUDY ON THE GLUING ABILITIES OF SOLID SURFACE COMPOSITES
WITH DIFFERENT WOOD BASED MATERIALS AND FOAM PVC
49
9. KAMPERIDOU Vasiliki – BARBOUTIS Ioannis:
LATHE TOOL - IT’S DEVELOPMENT FROM THE ANCIENT TIMES TO NOWADAYS
57
10. KITEK KUZMAN Manja – ŠERNEK Milan – KARIŽ Mirko:
DESIGN AND MANUFACTURING OF ORGANIC SHAPE FURNITURE
65
11. KLARIĆ Miljenko – PERVAN Stjepan:
IMPORTANCE OF BOTANICAL BINOMINAL NOMENCLATURE FOR
HYDROTHERMAL WOOD PROCESSING
71
12. KUTNAR Andreja – KUŠAR Tomaž – KITEK KUZMAN Manja:
ENVIRONMENTAL IMPACT ASSESSMENT AS PART OF FURNITURE DESIGN
81
13. KYUCHUKOV Georgi – GRUEVSKI Georgi – MARINOVA Assia –
KYUCHUKOV Borislav – JIVKOV Vassil::
COMPARATIVE ANALYSIS OF STIFFNESS COEFFICIENTS OF END AND
T-SHAPE CORNER JOINTS OF FRAME STRUCTURAL ELEMENTS WITH TWO
TYPES OF CROSS SECTIONS MADE OF SWEET CHESTNUT WOOD
87
14. MIKLEČIĆ Josip – JIROUŠ-RAJKOVIĆ Vlatka – ŠPOLJAR Marin:
DURABILITY OF WATERBORNE COATING SYSTEMS FOR WOODEN WINDOWS
95
15. NESTOROVIĆ Biserka – GRBAC Ivica – NESTOROVIĆ Predrag:
NUMERICAL ANALYSIS OF LAMINATED WOOD STRUCTURES - CHAIRS BY
APPLICATION OF FEA
101
16. PALIJA Tanja – VUČKOVIĆ Aleksandar – JEVTIĆ Petronije – JAIĆ Milan:
THE IMPACT OF WOOD STAINING ON THE ADHESION OF
CERTAIN TYPES OF COATING
111
17. PERIĆ Ivana – GRLADINOVIĆ Tomislav – STARČEVIĆ Igor –
STASIAK-BETLEJEWSKA Renata::
ON ENHANCING OF PRODUCTION PLANNING IN WOOD PROCESSING
AND FURNITURE MANUFACTURING
119
18. SMARDZEWSKI Jerzy – MAJEWSKI Adam – PREKRAT Silvana:
EFFECT OF CELL-WALL ANGLE ON THE UNIAXIAL CRUSHING BEHAVIOUR
OF PAPER HEXAGONAL HONEYCOMBS
127
19. STANKEVIK SHUMANSKA Mira – MELOSKA Živka – EFREMOVSKA Violeta:
IMPACT OF THE ECONOMIC CRISIS ON THE WOOD INDUSTRY PRODUCTION
IN REPUBLIC OF MACEDONIA
137
20. STASIAK-BETLEJEWSKA Renata:
CONSTRUCTIONS OF THE ENERGY-SAVING WOODEN HOUSES AND
ITS ADVANTAGES ON THE EXAMPLE OF POLISH CONSTRUCTION
143
21. SVOBODA Jaroslav – TAUBER Jiří:
MICROCLIMATIC CONDITIONS FOR HEALTHY SLEEP AND REST –
INFLUENCED BY SCIENCE, PSYCHOLOGY AND DESIGN
151
22. ŠIMEK Milan – KOŘENÝ Adam – DLAUHÝ Zdeněk – MIHAILOVIĆ Stefan:
POSSIBILITIES OF CNC MANUFACTURING WITH REGARD TO FURNITURE
DESIGN
157
23. ŽUPČIĆ Ivica – GRBAC Ivica – BOGNER Andrija – ŽULJ Ivan – LJULJKA Boris:
INFLUENCE OF MOISTURE CONTENT ON THE STRENGTH OF WELDED JOINTS
167
24. YAPICI Fatih – ESEN Raşit:
THE EFFECTS OF PRESS TIME AND PRESS PRESSURE ON MODULUS OF RUPTURE
AND MODULUS OF ELASTICITY PROPERTIES OF ORIENTED STRENGTH BOARD
(OSB) MANUFACTURED FROM POPLAR WOOD
175
25. YORUR Huseyin – YAPICI Fatih – ESEN Rasit:
THE EFFECTS OF CAST-POLYAMIDE ON THE MODULUS OF RUPTURE AND
MODULUS ELASTICITY OF ORIENTED STRENGTH BOARD (OSB)
MANUFACTURED FROM SCOTCH PINE
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WOOD IS GOOD
USER ORIENTED MATERIAL, TECHNOLOGY AND DESIGN
Klismos - The Style and Form of the Ancient Greek Chair
BARBOUTIS Ioannisa*– KAMPERIDOU Vasilikia
a
Aristotle University of Thessaloniki, Faculty of Forestry and Natural Environment, Laboratory of Wood
Products and Furniture Technology, Thessaloniki, Greece
*
Corresponding author: [email protected]
Abstract - The Greek furniture tended to be round, curved, ornamental, comfortable, supportive to the
body and functional. The most characteristically Greek furniture form was the klismos chair. Prior the
Greek klismos, chairs had hard stiff backs and arms, while klismos is a less extravagant piece of
furniture, an elegant Greek chair with a curved backrest and legs. Characterized by grace and
symmetry, klismos was essentially plain, with legs curving out from the seat and a back support
consisting of a simple rectangular panel curved inward from sides to centre. The chair acquired a
broad horizontal back slat at the top that encircled the shoulders of the seated person, establishing a
fixed form of the classic chair. It offered a new type of support for the back than the straight back, or
slanted back chairs of earlier times, while its light weight made it easily moveable. In this study the
form and style of ancient Greek chair klismos are presented and analysed, the evolution of the
architecture and designs of ancient Greek chair through the ages, while valuable information is also
recorded about the methods, the materials and types of connection used in klismos construction.
ancient / chair / design / furniture / Greek / klismos
1. INTRODUCTION
As the years went by, primitive man having satisfied the basic needs and having solved
some of his basic problems like food, clothing and shelter, he embarked on a synthetic task
and manufacturing operation, in which raw materials were manufactured and transformed into
useful objects, among them also furniture. He realized that the human body performs a serious
task, probably that it is a living organism which gets tired and needs to rest, so he invented
constructions for repose, which nowadays are called beds, chairs, stools, etc. In order to meet
other human needs other kinds of furniture was created respectively, for example to store and
deposit fruits and other goods such as shrines, lockers, banks etc. were created.
In the ancient Greek house there were no complex and multicomponent furniture. There
were few pieces of furniture and among them there was the klismos, a chair that is well
known for its harmony and beauty, since it erects from the floor with calm curves and results
in deep elliptic back (SARIDIS, 1982). Klismos is an autonomous Greek creation that does not
have its origins in Egyptian or Assyrian patterns, as with some other types of ancient Greek
furniture like stools, tables, beds, etc. (RICHTER, 1959).
As it is known, in ancient Greece the son or daughter that was going to marry, was taking
as dowry from the family home, among other things also furniture. Undoubtedly, among other
things, the furniture in Ancient Greece was also a means of social promotion and
demonstration object. Quite remarkable is the fact that the production of elegant furniture of
best fit and quality was a source of enrichment for ancient cities or regions like Chios, Miletus
and Thessaly. The Greek furniture tended to be round, curved, ornamental, comfortable,
supportive to the body and functional. From the 6th century BC, already formed Greek
furniture are presented, which are clearly of Greek inspiration, elaborate, full of grace and
harmony, elegant and simple (SARIDIS, 1982).
The image of the excavation material in relation to the architecture of the Late Classical
and Hellenistic houses indicates that the amount of furniture in homes is proportional to the
house area, the availability of materials in the surrounding area, the cost and of course the
time one spending in the house. The quantity of perishable furniture cannot be accessed, but
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WOOD IS GOOD
some assumptions could be made: wooden furniture was used widely in areas where wood is
abundant (e.g., Macedonia), and possibly the construction did not require in all cases
professional carpenters or joiners. The daily life did not necessarily require furniture in house,
and there are iconographies that depict also dinners on the floor. Reports such as Menander
declare that the furniture that we see most often depicted in the vessels were in homes of most
privileged and was not the rule in all homes. The time of being inside the house was the other
reason for not having too many furniture in the house. It is a fact that many household work
takes place in the backyard or outdoors because of limited light in the house, which is the
reason probably that they used furniture of easy transportation. Although some windows were
found in Hellenistic Greece in Vergina Palace (houses of late Hellenistic Delos imitation
windows on the grave of Lefkada) to name a few examples, large windows, bringing light into
the house, appear only after the 1st century B.C. There is also vagueness about the placement
of furniture in the house, which indicates that the areas of the house were not dedicated to a
single occupation, like today. The practice of separating specific spaces as bedrooms,
kitchens, bathrooms, living rooms, etc. belongs to the 18th century and even more in the
1930s. Therefore, the house in antiquity should be seen as a vague space where everything
happens according to the time of the day, the climate, the mood of owners, dimensions of the
room, the number of persons who are at home that time etc. (ANDRIANOU, 2009).
The necessity, usability and the main types of furniture did not changed materially from
the ancient times to the present. Klismos was selected to be analysed and presented in this
paper because it presents great interest from manufacturing point of view in relation to other
types of furniture. From the existence of some klismos can be derived the metrology, their
detailed dimensions and evidence of typological evolution, elements which help us in
substantial study and conclusions about this seat. As often happens with archaeological data
since the material remains of furniture of the houses are not enough to form a complete
picture, researchers try to fill in the gaps, as far as possible, by combining findings from
various geographic excavation places literary sources and iconography (ANDRIANOU, 2009).
2. HISTORY AND MORPHOLOGY OF KLISMOS
Generally, available material for information about the furniture of ancient Greece offer
apart from the written tradition and the ancient monuments (sculptures, reliefs, vase paintings,
frescoes, mosaics, coins, jewellery and stamps). The word klismos is a compound word with
the first component «κλι-»(kli) coming from «κλίνειν» (klinin) which means recline and has a
direct relation to the «κλίνη» (klini) (bed). The word klismos was basically used to describe
the comfortable chairs with curved backrests and legs that are not thrones.
Klismos is presented only in sculpted works or reliefs, as well as, angiography.
Paradoxical and difficult to interpret remains the facts that while other archaeological sources
depicted innumerable forms of other types of furniture, klismos was not shown.
From the earliest Neolithic period (6000 - 5000 BC) the type of a seated male figure has
already formed, as evidenced by the clay effigy of seated man from Pyraso of Thessaly, which
sits majestically on the stool with his hands resting on the thighs and knees. Respectively,
identical seats were found in many Neolithic settlements in Thessaly. The two curved legs
stool illustrated in that effigy are constructed with curved branches and have a flat mounting
for the man who is seated (ALEXIOU, 1992).
During the Bronze Age that follows (2800 - 1100 BC) several metals were widely used
(copper, gold, silver), and therefore, more powerful, bronze tools were constructed and used.
The general intellectual, cultural and tooling development and realization of anatomical
needs, such as support and rest of the user's back seat contribute in the evolution of the seat in
a seat bearing a backrest. The form of klismos probably came from the evolution of some type
of seat of the geometric or archaic period (RICHTER, 1959).
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A.
B.
C.
Figure 1. A., B., C. Klismos illustrated in angiography
The addition of the backrest is an important innovation because it shows that
cabinetmakers comprehend that the furniture is a "nest" or "embrace" or "template" that
accepts man to sit down, work or rest. It is true that the seat without backrest (stool) still
remains in use, just like today. Great importance held that the manufacturers were aware of
the anatomy of movement and function of the human body (ergonomics - anthropometry), as
evidenced by the proportions of a chair and the dent on the top surface of the seat for better
hospitality of buttocks. Klismos has often integrated a footrest/footstool between the two front
legs, in order to place the feet and rest them and it was mainly used by mortal people that are
socially superiors. Usually, this small piece of furniture was separate from the furniture of
klismos. In ancient literature the form of a klismos was not fully described as we know it from
the ancient Greek artworks, possibly because Homer often refers to another Mycenaean chair
that is tripod.
Klismos was being used by men and women of any age and post, equipping homes,
workplaces, palaces, in which case apart from simple chair it functioned as throne. The basic
construction material of klismos was wood, and there were more lavish klismoi made of gold,
either solid gold or of gold leaves, or silver with ivory in the back of the chair. Often a chair
was covered with precious fabrics and animal skins, which is illustrated also in pots or
tombstones.
Klismos consists of two front outwards curved legs, which are wide at the top and narrow
at the bottom. The two rear legs are also curved outwards and here there is a progressive
reduction of the leg width from the height of the seat and downwards. The hind legs extend
over the height of the seat, creating a curve inwards. Thus, the elongated upwardly hind leg
has the shape of "S" with gentle curves. The front legs are connected with the hind ones at the
height of the seat with four edge beams-transoms, with joints of mortise and tenon, pegs or
dowels. In the upper part of the rear leg rests a curved plank, that nowadays is called "omitis",
in order, on the one hand, the seated person to rest the shoulders and on the other hand, for
structural, static purposes and support of the furniture. In the interval between the lower part
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of "omitis" and the highest point of the rear beam-transom, there is a slightly curved plank,
which now is called “label”, which supports the backbone of the seated person. The chair of
klismos is usually austere; it does not bear a particular decoration, such as lion feet, heads of
swans etc. nor transoms between the legs (ALEXIOU, 1992). Mainly in the first appeared
klismoi, the backrest often bended backwards, where a head swan or a palmette overtopped.
The morphology of klismos is based on specific set of curved elements, so it is easily
recognizable furniture. Nevertheless there are variations in the heights, the dimensions of the
“omiti”, the curvature of the legs etc. Frequently, we observe ancient Greek furniture that
folds, such as folding stools, thrones etc., while klismos does not present this kind of folding
design.
A.
B.
Figure 2. A., B. Configuration of klismos with wide “omitis”
Klismos is mainly illustrated in pottery within everyday life scenes, which demonstrates
that it was not used as a throne. It also stands out for its simple and rectangular form and it got
its basic form elements from the throne. From mid 5th century BC when klismos started to be
widely used, it replaced to some extent the use of throne. The stone klismos was destined for
outdoor environment, whereas the wooden one for indoor use. Unfortunately no wooden
klismos survived till our times, because through the years this wood has been found under the
appropriate conditions for growth of decay fungi, which totally destroyed these furniture
pieces. Wood was used dry by the craftsmen, since they had already known that wet wood
causes checks, bending and distortions to the final structures. Furthermore, the ancient
craftsmen used to dry out the wood naturally, covering it sometimes with manure, to protect it
from the abrupt changes in weather conditions. In 475 BC, according to the ancient
monuments of Greek art, the classic type of klismos was established, that specific type with
the “omiti” which rests at the top of the rear legs (ALEXIOU, 1992).
Based on the illustrations of klismos and on the stone klismoi that were rescued, one
could declare that the height of a klismos was 46 centimetres ±2. The acceptance of the height
of existing stone chairs as a base for the metrology of such furniture is essential, since the
depictions of klismos in other monuments such as vases, tombstones etc. do not reflect the
real dimensions. Based on the dimensions of existing chairs, the proportions seem to create a
sense of order and harmony among the elements of the chair synthesis. Thus, the imaginable
rectangle with dimensions of 23x26 cm, in which the low backrest of a chair and the seat
surface are two times smaller than that which the surface of the seat with the legs are included
and has dimensions of 46x46 cm.
The unfussy morphology of the classic klismos, derived from all the curved elements that
are comprised by, makes it undoubtedly one of the most beautiful creations in the field of
furniture, combining relaxation with morphological simplicity and grace. Over the years, the
shape of klismos evolves and the proportions are modified. Thus, the narrow “omitis” that
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eminently dominated in the late Archaic and early Classical era, widens considerably during
the Hellenistic era. The morphological relations between the seat, in relation to the other
proportions of the furniture and the bowing of the legs etc. are all improved. Each piece of
klismos is a unique chair and its construction is not precisely repeated, because it is difficult
to achieve this, but also because of manufacturing specialties of klismos. Several attempts
have been made to make a classification of klismos, based mainly on dimensions and
proportions each one has. “Omitis” is characterized to be “narrow”, when it is narrower than
the ½ of the height of the seat, regardless of the total height of klismos or the height of seat.
Mainly during the late classical and Hellenistic era the wide “omitis” predominates. Typical
example of a klismos with a narrow “omiti” is the famous chair, the klismos of Hegeso
(«Ηγησώ»), depicted in a relief on the famous Attic Tombstone and dates from the late 5th
century BC. There are also klismoi with “omiti” of “equal size”, in which the “omitis” height
is equal to the half of the seat height, regardless to the total height of a chair, the slope of the
seat backrest or the legs curving. This type is established in 450 BC and does not appear
often, but still appears till the Hellenistic era (ALEXIOU, 1992).
A.
B.
Figure 3. A., B. Characteristic pictures of Ancient Greek klismos: A. in tombstone of Hegesus, B.
tombstone found in Viotia (late 5th cent. BC)
In the klismos category with a back rest of “equal dimensions” belong the chairs, whose
backrest height is equal to the height of the seat. This type probably first appeared in the early
5th century BC and was repeated continuously on pottery, tombstones and votive columns up
to the first fourth of the 4th century BC. In fact, in some klismoi also the depth of the seat
corresponds and complies with these dimensions.
The most common type of klismos is that in which the backrest height is greater than the
height of the seating surface. The very high backrest first appeared in the early types of
klismos (around 520 BC), which had a decoration with swans heads, as has been mentioned
earlier. The presence of this klismos type continues to appear until the end of the 1st century
BC, as evidenced in tombstones, depictions on vases and the surviving stone chairs. Several
times this klismos type presents narrow “omiti”, probably in order the harmony to be
achieved in this klismos, which is considered the one of lower aesthetics (ALEXIOU, 1992).
The backrest of a chair, regardless of its height, forms an angle to the seating surface, which
differs from klismos to klismos. Klismos with a vertical backrest, where the seat back forms
an angle of 90o to the seating surface is a relatively rare type of klismos and is found mainly
in seats of prehistoric period. A seat of this kind makes the body form a right angle with
thighs, an attitude that nowadays is considered to be not at all ergonomic for rest. It could be
more suitable for occasional seating in dining rooms or in short time gatherings. During the
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more suitable for occasional seating in dining rooms or in short time gatherings. During the
Classical era this klismos type reappears after 475 BC and continues to be met until the mid3rd century BC.
The klismos with canted backrest is one of the most popular used klismos. The backrest
is inclined about 110o±5o, from the seating surface. Klismoi with canted backrest appear since
the prehistoric era. This slope allows the relaxation and rest of the body, which is
compounded even more when the slope of the seating surface is 5-7o upwards, even though
the seating surface of klismos was usually completely horizontal. A rare type of klismos is
that, in which the backrest forms an angle of about 130o±5o with the seating surface. This
extreme slope of the backrest, which actually transforms the furniture into a cline, can offer
the absolute rest, only under the basic condition that the seating surface is inclined 5 – 15o, in
order the seated person to avoid sliding forwards. The specific type of klismos appeared only
during the 5th century. The horizontal label is already found in klismoi of prehistoric era,
when the prehistoric craftsmen quite wisely considered it necessary to have this item in the
middle of the backrest to support the human backbone. Unfortunately, most of klismoi are
laterally depicted on the monuments, so the presence of the label is not always visible. On the
other hand, there is a small but sufficient number of klismoi represented on their front side or
designed prospectively, as in seated statues, or in the surviving stone klismoi that can be
substantiated both the existence and morphology of the label.
The curving of the legs, irrespectively of the height or the seating surface depth,
corresponds to an arc of a circle or an ellipse, most of times. The curved legs of klismos of
“Hegeso” are arc of ellipse with major axis of 39.5 cm and a minor axis of 25 cm. However,
the chord of the arc of the front leg is longer (38 cm) than that of the rear leg (36.5 cm). The
curved legs of that type of klismos are normal, since most of klismoi are found to have similar
sizes and carvings, while only minor deviations have been detected. It is extremely rare the
phenomenon klismos to obtain vertical legs. However, from 510 BC a klismos type appears
which has vertical hind legs and curved front legs. This type of klismos still appears until the
end of the 5th century BC, perhaps even later (ALEXIOU, 1992).
The surface of seating is created using several bands which are placed and fixed from one
edge to the opposite, thus they often cross with each other, creating a comfortable seating
surface. Careful observation of klismos illustrations on pottery revealed the following four
different ways, in which the leather bands were tied in rows to create the seating surface of
klismos: 1. in doubles, triples or hexads, which is the most usual way of tying the bands, 2. in
series, which is quite common way 3. combination of the above tying ways with cross way, 4.
only cross wisely. The last two ways are much complicated and therefore, are not so
commonly used in tying the bands of the seating of klismos (ALEXIOU, 1992).
The curved wooden members of klismos were not manufactured by carving a bigger
wooden element to smaller, but with other more advanced techniques. The technique of
bending the board mechanically was widely applied in ancient Greece (evidenced by
Theophrastus). The bending was implemented using steam or soaking the piece for a long
period in amorgos-olive, a substance that was used by the ancients as therapeutic - demulcent
substance, and also to soften skin and wood. Afterwards, the wood was placed in a special
mould in order to achieve the desired shape. Another version for the manufacturing of curved
wooden elements is the use of laminated timber technique, which was already known in
ancient Egypt.
The use of curved legs imposed the use of very resistant to loadings forest species.
Mainly hardwoods were selected (beech, oak, etc.) rather than softwoods (pine, fir, cypress,
etc.). The hardwoods were more easily rubbed, polished, bent, while they are also more
durable and dense wood species. Several adhesives were being used in klismos assembly and
construction. Various glues of plant origin were used, such as starch paste, Arabic gomi,
gluten, glue of Semolina and pollen or of animal origin, such as casein, glue coming from
blood, collagen protein etc.
6
WOOD IS GOOD
For the preservation of klismos or other furniture of those times, two types of protective
substances must have been used. Firstly, substances applied on surface or varnishes that have
little penetrating potential and create a very thin film on its surface. These substances were
usually originated from vegetable and pathological or traumatic tree secretions, such as gum
of acacia, the balsam, generally komeoresines, derived from coniferous trees etc. These
substances, however, can be also of animal origin, such as beeswax or the white part of egg.
Secondly, there were impregnating substances that were totally absorbed by the wood pores,
such as animal fat, oil derived from the cedar pith and amorgos from olives (ALEXIOU, 1992).
The tools used most frequently were the axe, the saw, the deception, the hammer and lathe.
Besides the classical joints of wood, such as mortise and tenon, dowels etc., used in the
construction of klismos, metal studs and adhesives were also used (R ICHTER, 1959). The
joints of wooden elements in a chair were hidden and covered wisely with precious wood or
metals.
The decoration of klismos could be accomplished by the same the klismos craftsman, but the
elaborate decoration of luxurious klismoi certainly would be undertook by a chair specialist/
decorator (gold-plating, ivory craftsman, painter etc.) who knew the art of decorating these
furniture. Frequent decorative element of Classical and Hellenistic periods klismos were
glyphs (grooves) that were carved on the four corners of the front and rear legs, as in the
klismos of “Hegeso”. As mentioned earlier, palmettes, heads of swans and spirals often
adorned the ends of the backrest, while the label was often adorned with various
representations, satyr’s pictures, grapes and other relief decorations. Klismos often displayed
a decoration of paints or written representations, while part of the decoration could be also
regarded the intonation or discoloration of a cheap wood, which after the appliance of paints
and varnishes gives the impression of quite luxurious furniture.
3. CONCLUSIONS
During the Bronze Age (2800-1100 BC) a backrest was added to the plain stool and the
first type of klismos started to appear and be formed, which is a seat of simple morphology
and does not bear hand props. klismos is illustrated in numerous ancient Greek artworks from
the Archaic, Classic and Hellenistic periods. Over the years, there has been recorded a rich
typological evolution of klismos and while initially it was characterized by a rich and heavy
ornamentation (archaic period), due to the fact that it was derived from a throne, then it was
turned into a simple, attractive and comfortable seat (classical era). The major importance of
klismos for people everyday life is proved, except for the ancient Greek literary sources, also
by its frequent depiction on tombstones, which indeed indicates funerary luxury, which could
be demonstrated only socially prominent and wealthy people.
4. REFERENCES
ANDRIANOU, D. (2009): The Furniture and Furnishings of Ancient Greek Houses and Tombs. New
York: Cambridge UP, 2009.
SARIDIS, Ε. (1982): The ancient Greek furniture. Archaiologia, Issue 2: pp. 65-67.
ALEXIOU, P. (1992): The ancient Greek Klismos. Doctoral thesis dissertation.
RICHTER, G. (1959): A handbook of Greek art. Phaidon Press Ltd., London.
7
WOOD IS GOOD
Quality of the Wooden Products for Design and Equipping Educational
Institutions
DOMLJAN Danijelaa*– VLAOVIĆ Zorana – ŽUPČIĆ Ivicaa – ŽIVKOVIĆ Vjekoslava
JIROUŠ-RAJKOVIĆ Vlatkaa – GRBAC Ivicaa
a
Department of Furniture and Wood Products, Faculty of Forestry, University of Zagreb, Zagreb, Croatia
*
Abstract – Equipping educational institutions with quality and contemporarily designed furniture and
equipment is a serious problem in Croatia. There are many inconsistencies and the quality of furniture
and equipment is rather low (e.g. dimensions, materials, etc.). All these problems are partially a
consequence of inadequate technical descriptions and lack of quality attributed to the products in use,
especially in cases where companies bid on public tenders. With the aim to improve the conditions for
equipping educational institutions with furniture and equipment, a team of experts at the Department
of furniture and wood products of the Faculty of Forestry in Zagreb published the Manual for Wood
Products Quality for Educational Institutions in the framework of the project entitled Wood Is Good.
The intention of the Manual is to stimulate and introduce high-quality furniture, equipment,
construction products as well as other wooden products into the public procurement system, actively
involve architects and designers in the production and motivate responsible methods for monitor and
control production and delivery of wood products for equipping educational institutions. The authors
believe that this document can serve as the platform for interdisciplinary analysis of various problems
related to equipping educational institutions and preserving health of users.
furniture / educational institutions / equipment / design / technical description
1. INTRODUCTION
One of the most important problems noticed over a longer period of time in Croatia is
primarily related to inconsistency and lower quality of products procured for the educational
institutions along with inadequate materials used in production which prove to have harmful
effects on health (DOMLJAN, 2011). The existing written documents about pre-school, primary
and secondary education in most cases do not pay enough attention to quality of adequate
furniture and equipment or other products needed in educational institutions for all activities
related to the educational process and psycho-physical, cognitive and other needs of children
and youth (PASALAR, 2003; HIGGINS et al., 2005; DUDEK, 2005; GRBAC – DOMLJAN, 2007;
DOMLJAN, 2011; DOMLJAN – VLAOVIĆ, 2011). Aside from non-quality materials, problems
often arise because of disproportioned dimensions of furniture in relation to end-users which
can even result in health problems such as MSD/LBP (LINTON, 1994; KNIGHT – NOYES, 1999;
PARACELLS et al., 1999; HAVIAROVA et al., 2001; WATSON et al., 2002; DOMLJAN, 2011).
Producers hold certificates on the tested furniture quality proving that all precondition have
been met and such documents are delivered in public procurement procedures but thus
procured furniture very soon gets ruined and proves to be inadequate for users’ needs. The
biggest problems result from non-observation of required descriptions contained in the
technical specifications or inadequacy of technical descriptions lacking clarity and detailed
elaboration. This results in self-willed interpretation on the behalf of incompetent investors
who often do not consult experts. In many cases public procurement procedures for equipping
educational institutions do not control the quality of procured products since they do not
demand delivery of product samples or at least photographs showing the elements of an offer.
The result is a wide range of products delivered for facilities that are rarely controlled in the
final phase of the delivery and usually do not correspond with the basic standards of quality in
respect of preservation of children and young people’s health (DOMLJAN – VLAOVIĆ, 2011).
9
WOOD IS GOOD
1.1. Problem
Croatian educational system comprises pre-school, primary, secondary and high school
education and institutions of higher education (***, 2012) and education takes place in
facilities for a designated purpose such as kindergartens, schools or colleges. There are
several documents clearly describing the procedures to be applied in equipping and defining
the type and quantity of furniture for every room also stating information about how the
interiors and exteriors of educational institutions should look like (AUF – FRANIĆ et al., 2003;
AUF – FRANIĆ et al., 2004). From an architectural point of view, such interiors and exteriors
in most cases have modern designs and responsible construction. However, the selection of
furniture, equipment, flooring, doors, windows and other wood products used for interiors
very often leaves this important segment for decision-making in hands of incompetent
professions. Croatia lacks adequate and sufficient literature describing possible procedures for
equipping educational and pedagogical facilities, defining quality, dimensions, requests and
regulations for particular types of furniture, design and construction solutions as well as other
details about how to equip educational facilities with quality furniture and wood equipment,
floors, carpentry and other wood products (DOMLJAN, 2011; Case study for the 2002-2013
period). In general, the influence of products on the overall educational and pedagogical
process and end-users is insufficiently taken into consideration. Over the past twenty years the
Croatian educational system has introduced some important reforms that, among other things,
intend to introduce co-working methods for learning and research. Unfortunately, those
reforms have not changed the perception and design of furniture and equipment so that
children work on old-fashioned, poorly designed furniture that does not correspond to
functional and ergonomic requirements and use equipment that prevents them from
participating in the new teaching and learning processes (DOMLJAN, 2009; DOMLJAN, 2011).
This is mostly the case in primary and high school facilities and very often in kindergartens,
too. All the above-mentioned factors indicate the most important problem conditioning the
present situation where children and young people remain exposed to products that reflect
negatively on their healthy development.
Aiming to improve the conditions for procuring furniture and equipment in educational
institutions, the team of experts at the Department of furniture and wood products of the
Faculty of Forestry, in Zagreb in the framework of the project entitled Wood Is Good and
financed by the Croatian Chamber of Economy, Hrvatske šume d.o.o. and the Ministry of
Agriculture, carried out the project named Publication of the wood products technical
description book. The project took place from April 2012 to April 2013 and included
cooperation between interdisciplinary experts from various fields such as medical science,
ergonomics, economy, public procurement, wood constructions and technology, architecture,
design and other. Field research, data collected from the existing documents and scientific
research resulted in the Manual for Quality Preparation of Technical Descriptions for Wood
Products Used in Educational Institutions.
This paper reflects on the Manual, its objective, aim and application.
1.2. Project purpose
The purpose of this Project is to stimulate the introduction of high-quality furniture,
equipment, construction, products (doors, windows and floors) as well as other products made
of wood and wooden materials in line with the HRN EN norms into the public procurement
system and other procedures related to equipping kindergartens and primary and secondary
schools in Croatia. This can be done by means of technical descriptions, recommendations,
norms and specialized product descriptions for wood products and materials used for
equipping educational facilities. Apart from the above-stated, the purpose is also to engage
other professions, such as architects and designers, in the creation of wood products and
stimulate responsible mechanisms for monitoring and controlling production process and
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WOOD IS GOOD
delivery of wood products used in equipping. Thus, all procedures related to decisionmaking, procuring and equipping necessarily have to involve not only investors and
producers/suppliers of furniture and other wood products, but also other professionals such as
architects, designers, constructors, quality experts, medical specialists, experts in ergonomics
and other in order to improve product quality and competitiveness as well as to find a solution
for the problem related to inconsistency noticed in the present procedures used for equipping
educational facilities. The intention is also to stimulate the application of the new solutions (in
terms of design, construction, technology and so on) for wood products founded in
contemporary scientific research and expertise.
1.3. Project objective
The main objective of the Manual is to provide a framework for defining quality in
technical descriptions for particular wood products that are most often used for equipping
kindergartens and schools and which are defined in the existing regulations and documents on
the national level. To be more precise, the main objective is to introduce a unified and
comparative quality system for wood products that could be used by producers/suppliers in
order to competitively participate in public procurement procedures for equipping educational
facilities and improve the quality and better use of wood products.
2. RESULT OF THE PROJECT – THE MANUAL
Manual for Quality – Preparation of Technical Descriptions- Wood Products - Tome I –
Educational Institutions is a result of the project named Publication of the wood products
technical description book. It is composed of three main parts.
The FIRST PART is composed of chapters entitled About the manual, which contains
some basic remarks and explains the purpose, objective and expected results of the Project,
whereas the second chapter entitled Contemporary findings serves as an introduction in
various problems linked to equipping educational facilities, lists all the existing documents in
Croatia and analyses the results of scientific research in the field of contemporary educational
processes, etc.
The SECOND PART represents the main part of the Manual and contains three chapters.
The chapter An introduction to wood product quality describes general conditions and quality
factors and provides explanations for some of the basic terms contained in the Glossary. This
part of the Manual also gives recommendations for the norms applied in the field of furniture
and furniture parts as well as characteristics for construction and other wood products. Next
chapter Furniture and equipment lists the most important requirements and recommendations
for designing furniture and equipment. These include specifications for technical quality,
constructional and safety regulations, ergonomic and anthropometric factors, pedagogical and
esthetical requirements, application of wood and non-wood materials, surface finishing,
upholstering and other. The most important examples are given and described for various
types of furniture used for storing, working and consuming food, sitting and lying together
with equipment elements. Technical descriptions are also given for some of the typical
examples for each particular type of furniture. The last chapter of the Second part
Construction products also provide a list of requirements and recommendations and describe
some exemplary prototypes in this category: doors, windows and wooden floors.
The THIRD PART and the chapter Visions and new proposals for equipping is intended
for all types of users, i.e. children, young people, parents, teachers and others but mostly for
those who participate in designing and equipping educational facilities or designing and
producing furniture and equipment that will be used inside of such facilities.
Follows Conclusion and References with more than 120 quotations.
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WOOD IS GOOD
3. QUALITY OF THE WOODEN PRODUCTS
The biggest problem in equipping facilities is quality of furniture and wooden products
with their technical descriptions. If a particular technical description is incorrect and written
unambiguously there is a possibility that investors, producers, procurers and other interested
parties in the process of procuring and equipping educational institutions simply cannot
understand the overall process.
Aiming to achieve a unified quality of technical descriptions for particular wood products
that are most frequently used for equipping educational institutions, the Manual lists some of
the basic elements of furniture and equipment whose typology is founded in the Croatian
Pedagogical Standards (***2008a, ***2008b, ***2008c), together with expended variants for
each type.
Wood products used for equipping educational institutions in most cases comprise
furniture for sitting and working (chairs, armchairs, tables and other), furniture for lying
(beds), furniture for storing (cabinets, shelves, glass cabinets and other), and construction
products (doors, windows, wooden floors). The Manual contains more than one hundred
wood products described as possible but not single solutions. Various specificities and
characteristics are defined for each group (type) along with relevant explanations for
individual product typology. Each individual product belonging to a particular type is
presented spatially (sketch) and described in a way it contains dimensions, purpose,
construction description, materials, processing, safety requirements and enforceable norms
and product variants (if there are any).
The items for furniture description on example of school cabinet are given in Table 1.
3.1. Product description example
This chapter contains a simplified example of a product technical description for a school
cabinet together with main defining categories (Table 1).
Table 1. Items for furniture description (e.g. cabinet)
TECHNICAL DESCRIPTION:
PRODUCT NAME:
PRODUCT USE AND BRIEF DESCRIPTION:
DESIGN AND QUALITY STANDARD:
FUNCTIONAL (OVERALL) DIMENSIONS: COMPOSED (w×l×h) / PACKED
TYPE AND QUALITY OF WOOD MATERIALS:
TYPE AND QUALITY OF NON-WOOD MATERIALS:
PROCESSING ACCURACY (FINESS) OBRADE:
CONSTRUCTIONS AND ASSEMBLING:
SURFACE PROCESSING:
PACKAGING:
4. CONCLUSION
Interiors used for education are not generic. Each new project should take into
consideration time, place and users as well as dimension of children and young people’s
healthy development. The entire process should be rational, responsible and defined by
norms, which does not presuppose their inflexibility. Thus, the Manual does not define single
solutions and designs but rather provides a set of recommendations, requirements and
research data for use in the production of quality wood products offering various possibilities
for design and further development and research.
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WOOD IS GOOD
Furniture and equipment are by no means the most important elements of educational
process but they strongly influence its methods and overall quality. Sometimes furniture and
equipment play a decisive role in motivating or discouraging students from learning and
participating in school work and protecting their health together with other factors listed in the
Manual. The authors believe that further research in the field should take that direction.
Present research indicates that most of attention, energy and resources were invested in
analysing working environments mostly used as offices and problems encountered by the
working population sitting in offices. Now is the time to reconsider healthy development of
children and young people in educational institutions where comfort, motivation,
communication and well-being play the most important role. New programmes, technologies
and working processes in all segments of educational system require changes. It is up to as, as
socially responsible beings, to stimulate, adopt and apply such changes for the well-being of
the youngest population and the society as a whole.
The Manual presented in this Paper is, hopefully, a contribution to such intentions.
5. REFERENCES
AUF-FRANIĆ, H.; OLUIĆ, V.; ŽARNIĆ, T.; BERTINA, M.; KORLAET, L.; RISTER, V.; ROTH-ČERINA, M.
(2003): Nurseries and kindergartens – guidelines for programming, planning and designing. (in
croatian) University of Zagreb - Faculty of Architecture, Zagreb, acta architectonica.
AUF-FRANIĆ, H.; OLUIĆ, V.; ŽARNIĆ, T.; BERTINA, M.; KORLAET, L.; RISTER, V.; ROTH-ČERINA, M.
(2004): Primary schools. Programming. Planning and designing. (in Croatian) Golden
marketing, Tehnička knjiga, University of Zagreb - Faculty of Architecture, Zagreb.
DOMLJAN, D. (2011): Designing school furniture as a precondition for preserving pupils’ health. (in
Croatian) Doctoral thesis. University of Zagreb, Faculty of Forestry, Zagreb.
DOMLJAN, D.; VLAOVIĆ, Z. (2011): Technical documentation for equipping kindergartens, Project:
Introducing standardized equipment and furniture in the pre-school educational system. (in
Croatian) University of Zagreb - Faculty of Forestry.
DUDEK, M. (2005): Children Spaces. Architectural Press, An imprint of Elsevier, Oxford, Burlington,
UK.
GRBAC, I.; DOMLJAN, D. (2007): Furniture for a healthy life, Sigurnost 49 (3): pp. 263-279.
HAVIAROVA, E.; ECKELMAN, C.; ERDIL, Y. (2001): Design and Testing of Environmentally Friendly
Wood School Chairs for Developing Countries. Forest Products Journal 51 (3): pp. 56-64.
HIGGINS, S.; HALL, E.; WALL, K.; WOOLNER, P.; MCCAUGHEY, C. (2005): The Impact of School
Environments: A literature review. Design Council. The Centre for Learning and Teaching.
School of Education, Communication and Language Science, University of Newcastle, UK.
URL: http://www.cfbt.com/PDF/91085.pdf
KNIGHT, G.; NOYES, J. (1999): Children’s behaviour and the design of school furniture. Ergonomics
42 (5): pp. 747-760.
LINTON, S.J.; HELLSING, A.L.; HALME, T.; ÅKERSTEDT, K. (1994): The effects of ergonomically
designed furniture on pupils’ attitudes, symptoms and behaviour. Applied Ergonomics 25 (5):
pp. 299-304.
PARACELLS, C.; STOMMEL, M.; HUBBARD, R.P. (1999): Mismatch of classroom furniture and student
body dimensions. Empirical findings and health implications. Journal of Adolescent Health 24
(4): pp. 265-273.
PASALAR, C. (2003): The effects of spatial layouts on students' interactions in middle schools: multiple
case analysis. Doctoral dissertation, Faculty of North Carolina State University, USA.
WATSON, K.D.; PAPAGEORGIOU, A.C.; JONES, G.T.; TAYLOR, S.; SYMMONS, D.P.M.; SILMAN, A.J.;
MACFARLANE, G.J. (2002): Low back pain in schoolchildren: occurrence and characteristics.
Pain, 97, pp. 87-92.
*** (2008)A: National pedagogical standard for pre-school education, Croatian Parliament, 16 May
2008. URL: http://narodne-novine.nn.hr/clanci/sluzbeni/2008_06_63_2128.html
*** (2008)B: National pedagogical standard for elementary school education, Croatian Parliament, 16
May 2008. URL: http://narodnenovine.nn.hr/clanci/sluzbeni/2008_06 63 2129.html
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WOOD IS GOOD
*** (2008)C: National pedagogical standard for high school education RH, Croatian Parliament, 16
May 2008, URL: http://narodne-novine.nn.hr/clanci/sluzbeni/339619.html
*** (2008)D:. HRN EN 1729-1: Furniture – Desk and chairs for educational institutions – 1st part:
Functional dimensions (EN 1729-1:2006), HZN Zagreb, CEN Brussels.
14
WOOD IS GOOD
The Effects of Press Time and Press Pressure on the Screw Strength
Properties of Oriented Strength Board (OSB) Manufactured from Poplar
Wood
ESEN Raşita*– YAPICI Fatihb
a
Karabük University-Technical Education Faculty- Department of Furniture and Decoration Education Karabuk
and Turkey
b
Karabük University- Forestry Faculty- Department of Forest Industry Engineering Karabuk and Turkey
*
Abstract – The effects of press time and press pressure on the screw strength properties of oriented
strength board was investigated. For this purpose, 80mm long strands made of Poplar were bonded
with phenol-formaldehyde resin at (9 %) with three-layer cross-aligned OSBs. The strands used for the
production of test panels were made up 50 % of core layer and 50 % of outer layers. The panels were
pressed for three different press times (3, 6 to 9 minutes), under 30, 40, and 50 kg/cm2 bar pressure,
aiming for a target density of 0.67 g/cm3. It was observed that the screw strength values were changed
between 637-945 N.
oriented strand board / phenol-formaldehyde / screw strength / mechanical properties
1. INTRODUCTION
Oriented Strand Board (OSB) is an engineered structural wood panel. OSB is made by
processing small diameter, fast growing trees into thin strands which are bonded together
under heat and pressure with an exterior resin binder. OSB panels are used various
applications such as building construction, furniture, roofing and flooring.OSB parts join with
nut, nail, and screw at using area (YAPICI et al., 2009).
In a previous study on OSB, wooden composite materials which are to contain panel
products such as medium-density fiberboard,particleboard, plywood, and (OSB). Besides, the
diminished supplies of larger dimension timbers have created high pricing (HU, 2000;
GRIGORIU, 2000). OSB has been found to have mechanical properties equal to those of
plywood for structure and to be manufactured comparatively cheaply (BROCHMANN et al.,
2004). It was reported that an increase of coment-wood ratio resulted in increase of all but
MOR values of OSB (ANTONIOS et al., 2006).
There are many important factors which affect physical and mechanical properties of
wood composite materials (GALBRAITH, 1986).When OSB roof or wall sheathing is exposed
to environmental moisture, it is degraded (BROCHMANN et al. 2004).
Researchers have studied the screw strength properties of wood composite materials by
using various processing variables. It is well known that the resistance of a nail or screw
shank to direct withdrawal from wood based materials is a function of several factors,
including nail diameter, and depth of penetration (FPL, 1999). It was reported that
demountable joints were more successful than stable joint in “T” joints used for the
production of frame construction furniture (IMIRZI, 2000).
In another study, since the middle layer structure of the particleboard embeds the screw
body, both mentioned parameters are considered important in the aspect of the quality of the
edge screw holding performance. In order to have further insight into the conformation of the
middle layer, the image survey was obtained on the split board section presenting the surface
of the middle layer (MILJKOVIĆ et al., 2007).
YAPICI et al. (2009) stated that as the increase of adhesive ratio, pres time and pres
pressure, which were used to production of the oriented strength board, the nail withdrawal
15
WOOD IS GOOD
strength increases. They also, reported that the nail withdrawal strength values were changed
between 124.60 and 334.81 N.
The production conditions of OSB panels are effective on mechanical and physical
properties of OSB. The most important parameters affecting the properties of OSB are press
pressure and pressing time. In this study, the aim is to evaluate the effects of press time and
press pressure on screw strength of OSB.
2. MATERIAL AND METHODS
Mature Poplar wood was used in the production of the (OSB). The strands dimension in
usage was approximately 80 mm long, 20 mm wide and 0.7 mm thick. Firstly, the wood
strands were dried until 3 % moisture content before adhesive was sprayed on them for three
minutes. Then, the adhesive material within 47 % liquid phenol- formaldehyde resin, was
applied in 9 percent ratios based on the weight of oven dry wood strands.
The press periods and press pressure were 3, 6 and 9 minutes under the 30-40 and 50
kg/cm2 press pressure, respectively. The shelling ratio was 50 % for core layer and 50 % for
face layer, and density of the boards was aimed at 0.67 g/cm3 density. OSB panels, which
were dimensioned as 56x56x1.2 cm were made for experiments, in the nine conditions. They
were 18 in total as two for each. Hand formed mats were pressed in a hydraulic press. These
panels were labeled from 1 to 6. All mats were pressed under automatically controlled
conditions at 195±2 ºC. After pressing, the boards were conditioned to constant weight at
65±5 % relative humidity and at a temperature of 20±2 ºC until they reached stable weight
(TS 642 1997). The density, moisture content, modulus of rupture and modulus of elasticity
values of OSBs were determined according to the related standards (TS-EN 323 1999; TS-EN
322 1999; TS EN 310 1999).
During the measurement of screw strength values were determined using Zwick/Roell
Z050 universal test device with capacity of 5000 kg and measurement capability of
0.01Newton in accuracy. In testing, loading mechanism was operated with a velocity of
10 mm/min. Data for each test was statistically analyzed. The analysis of variance (ANOVA)
was used (α<0.05) for testing significant difference between factors. When the ANOVA
indicated a significant difference among factors, the compared values were evaluated with the
Duncan test to identify which groups were significantly different from other groups.
3. RESULT, DISCUSSION AND CONCLUSION
The density (D) and moisture content (MC) values of OSBs were determined according
to the related standards. The average density and moisture content of panels were obtained as
0.67 g/cm3 and 7.4 %, respectively. It was seen that the aimed and acquired D and MC values
within the ranges specified in the related standards. The average and standard deviation of the
values of the screw strength of produced panels are shown in Table 1.
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WOOD IS GOOD
Table 1. Summary of the test results of the OSBs
Screw Strength (N)
Press Pressure
(kg/cm2 )
30
40
50
Press Pressure
(Minute)
3
6
9
3
6
9
3
6
9
Mean
Std. Deviation
735,86
1.006,24
1.093,43
453,75
892,36
842,35
722,75
613,09
823,36
45,10
83,81
31,82
39,40
126,44
112,42
92,04
35,62
228,60
It was found that the screw strength values of the test panels varied between 453.75 and
1093.43 N. The lowest value for screw strength of produced panels was 453.75 N (40 kg/cm2
and 3 minutes press time). The variance analysis of screw strength based on manufacturing
circumstances of test panels was done by using multi variance analysis (Table 2).
Table 2. The result of variance analysis
Type III Sum of
Squares
Corrected Model 1521914,64(a)
Intercept
28665980,28
Screw
Press pressure
487212,75
Strength
Press time
631928,70
(N/mm2)
Press press.
402773,20
*press time
Error
409018,20
Total
30596913,12
Source
Df
Mean Square
F-Value
8,00
1,00
2,00
2,00
190239,33
28665980,28
243606,37
315964,35
16,74
2523,05
21,44
27,81
Sig.Level
(p<0.5)
0,00
0,00
0,00
0,00
4,00
100693,30
8,86
0,00
36,00
45,00
11361,62
According to the variance analysis, the effects of the both press time and press pressure
on the modulus of elasticity values were significant statistically. Duncan test results
conducted to determine the importance of the differences between the groups are given in
Table 3.
Table 3. Duncan test Results
Application Type
Press Pressure
(kg/cm2 )
Press Pressure
(Minute)
50
40
30
3
6
9
Screw Strength (N)
Mean
HG
719,73
A
729,49
A
945,18
B
637,45
A
837,23
B
919,71
C
It can say that screw strength values changed between 637 and 945 N according to
Duncan’s test. Some homogenous groups were given the same column. It was seen that screw
strength values were affected by changing press time and press pressure.
In this study, the values of screw strength which were among the most important
mechanical features of oriented strand boards were determined according to related standard.
Especially, it can be stated that as the press time increased, the screw strength of test panels
17
WOOD IS GOOD
improved at the both press pressures. Although the highest screw strength related to 945.18 N
was obtained from experimental samples by applying 30 kg/cm2 press pressure, the lowest
screw strength of value related to 637.45 N was obtained from samples by applying 3 minute
press pressure time.
4. REFERENCES
BROCHMANN, J.; EDWARDSON, C.; SHMULSKY, R. (2004): Influence of resin type and flake thickness
on properties of OSB. Forest Prod. J. 54 (3): pp. 51–55.
FPL, (1999): Wood Handbook-Wood as an Engineering Material. Gen. Tech. Rep. FPL-GTR 113,
Madison, WI, Department of Agriculture, Forest Service, Forest Products Laboratory, 463 pp.
GRIGORIOU, H.A. (2000): Straw-Wood Composites Bonded With Various Adhesive Systems. Wood
Science And Technology 34, pp. 355-365.
İMIRZI, Ö.H. (2000): Mechanical Properties Of Massive Furniture “T” Joints With Frame
Construction. M.Sc. Thesis, Gazi University Institute of Science And Technology, Ankara.
MILJKOVIĆ, J.; POPOVIĆ, M.; MOMČILOVIĆ, D.M.; GRMUŠA, G.I. (2007): Edge Screw Withdrawal
Resistance In Conventional Particleboard And Osb - Influence Of The Particles Type.
ГЛАСНИК ШУМАРСКОГ ФАКУЛТЕТА, БЕОГРАД BIBLIB: 0353-4537 95, pp. 109-117.
PAO-JEN, (STEVE) H. (2000): Bending Stiffness Prediction For Oriented Strandboard By Classical
Lamination Theory, University of Toronto, 1-2.
PAPADOPOULOS, A.N.; NTALOS, G.A.; KAKARAS, I. (2006): Mechanical and physical properties of
cement-bonded OSB. Holz als Roh- und Werkstoff 64 (6): pp. 517–518.
TS 642/ISO 554 (1997): Standart atmospheres and /or testing; Specifications
TS-EN 323 (1999): Wood-Based panels,-Determination of density, TSE, Ankara.
TS-EN 322 (1999): Wood-Based panels,-Determination of moisture content, TSE, Ankara
TS EN 310 (1999: Wood-Based panels-Determination of modulus of elasticity and of bending strength,
TSE, Ankara.
YAPICI, F.; GÜNDÜZ, G.; ÖZÇIFÇI, A.; LIKOS, E. (2009): Prediction of Screw and Nail Withdrawal
Strength on OSB (Oriented Strand Board) Panels With Fuzzy Classifier. Technology, 12 (3): pp.
167-174.
18
WOOD IS GOOD
Analysis of User Preferences concerning e-trend in Kitchen Furniture
Design
FABISIAK Beataa*– KŁOS Roberta – MAĆKOWIAK Katarzynaa
a
Department of Furniture Design, Faculty of Wood Technology, Poznan University of Life Sciences, Poznan,
Poland
*
Abstract – The aim of the study was to collect information concerning evaluation of requirements for
furniture design created in e-trend. An additional practical objective was to propose examples of
selected concepts of kitchen furniture representing discussed trend. Based on the questionnaire studies
and direct interviews the data concerning lifestyle and using of new technology devices by users aged
40-60 and over 60 were gathered in order to identify the demand and need for providing furniture
meeting the requirements of e-trend way of living. The results of the comprehensive statistical analysis
performed on the collected data were presented, being the basis for creation of furniture concepts for
kitchen. The selected solutions of kitchen furniture design representing e-trend and aiming at
increasing the comfort of living were described.
design / kitchen furniture / e-trend in furniture design
1. INTRODUCTION
In consistence with the considerable technical progress in recent decades and the related
change in consumers’ lifestyles, the perception of domestic space has also been modified.
Designers have to follow these changes and respond to them adequately, creating products
potentially most effectively meeting the needs of contemporary consumers. In view of the
above the e-trend has been established in interior design, consisting in the implementation of
state-of-the-art communication technologies in traditional furniture and furnishings.
Application of such solutions in the kitchen space makes it possible e.g. to facilitate and
shorten the time required to prepare meals or to provide meals adequate for the diet of a given
user. When analysing the environment in which IT and communication technologies are used
it need to be remembered that the information and social space are formed by interdependent
networks of computers, devices and electronic media (PALCZEWSKA et al., 2011). Thus a
characteristic feature for e-trend kitchens will be connected with the virtual digital space,
facilitating for the room e.g. remote control over household appliances, communicators or
interactive surfaces. Moreover, this will provide constant access to the Internet, which
according to forecasts will become a window to the world, particularly for the elderly, thus
improving their quality of life in terms of e.g. professional career, interests or social contacts,
up to being completely independent (BATORSKI, 2010; BRADLEY – POPPEN, 2003).
In the future not only the kitchens, but also the entire living spaces will be transformed.
Flats will be changed into multifunctional spaces combining four basic fields of life connected
with the public sphere, home, work and leisure. The above mentioned spheres will overlap
thanks to the development of new technologies, products and services, which will meet and
satisfy the dreams, wishes and perceptions of users (JĘDRZEJCZAK – SPRYCHA, 2011). These
actions will be reflected in flats in the future. Thus the bedroom will be combined with the
bathroom, to be used for toilet, yoga, fitness, meditation and sleep, becoming a kind of an
oasis for physical and emotional health (SKALSKA, 2010; WANNINGER, 2009). Taking into
account the kitchen space it will be as compact as the bedroom and thanks to the new Air
Purifying technology (removal of aroma particles from it) it may be combined with the living
room. The same space will become the place to prepare meals, to work and to meet friends
19
WOOD IS GOOD
(QUINN, 2011; EDELKOORT, 2011). The kitchen space will thus considerably gain in
importance in comparison to its current status.
Most studies on the subject focus on the development of innovative devices used in the
kitchen, i.e. economical dish-washers, ovens indicating when a given dish is ready or fridges
monitoring the amounts and expiry dates of stored products (KRISHNAMOORTHY, 2001). Many
projects aiming at the application of computer technologies in the kitchen have focused on the
development of applications dedicated to e.g. interactive cook books or manuals establishing
the most nutritious menu (KRISHNAMOORTHY, 2001).
Taking the above into consideration the aim of the study was to collect information
concerning evaluation of requirements for furniture design created in e-trend. An additional
practical objective was to propose examples of selected concepts of kitchen furniture
representing discussed trend.
It was decided to divide the methodology into two stages. The first stage will consist in
conducting surveys and direct interviews in a group of 300 respondents aged over 40 years.
Due to the assumed futuristic character of the planned kitchen and the application of state-ofthe-art technologies in the project design it was decided for the share of respondents aged 40 60 years in the analysed population to be over 50 %. In the second stage the design
assumptions will be formulated and the concept for the furniture and interior design in the etrend will be established.
The survey questionnaire will consist of closed, open and semi-open questions. The
subject will cover problems concerning the use of computer tools by the users in the analysed
age group, activities performed in the kitchen and their preferences concerning the kitchen of
the future.
Collected data will be coded and next subjected to a comprehensive statistical analysis
using STATISTICA 10.0. Results of the investigations will constitute the basis for the
development and proposals of new solutions for kitchen furniture created in the e-trend,
which will potentially enhance the comfort of living of future users. They will be created
using the Google SketchUp. The final design of kitchen furniture will be presented using the
V-ray rendering programme.
3. RESULTS AND DISCUSSION
3.1. Results and discussion of survey research
In view of the percentage of returned questionnaires, the degree of their completeness and
the number of direct interviews the direct statistical analysis was conducted on data coming
from 281 respondents. The shares of individual age groups in the analysed population are
presented in Figure 1. Women accounted for 63 % respondents and predominated
quantitatively in each analysed age group.
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WOOD IS GOOD
Figure 1. The structure of the analysed group of respondents in terms of age and sex
Source: Own elaboration based on performed investigations
When designing furniture in the e-trend it is crucial to collect information on the
computer and Internet skills of the users in the analysed age groups. Results of conducted
analyses show that - as it could have been expected - the highest percentage of computer users
is found for individuals aged 40 - 50 years (84 %). However, a 38 % group of respondents
aged 61 - 70 using computers also need to be considered (Figure 2).
Figure 2. The structure of the analysed group of respondents in terms of age and computer skills
A relationship was shown between white-collar work and computer skills. As many as
90 % individuals performing white-collar work in the period of their professional activity
have computer skills. The analysed values are different in the case of individuals performing
manual jobs, among which it is true in case of 55 % respondents.
It needs to be stressed that among individuals using computers most (from 88 % in the
case of individuals aged 60 - 70 years up to 96 % users aged 40 - 50) also use the Internet.
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WOOD IS GOOD
What is interesting, such a situation is found in all analysed age groups (Figure 3). An
increasing number of individuals aged 50+ uses the Internet, which indicates changes
occurring among Polish 50-year olds (KRZYŻANOWSKA – DANIELEWICZ, 2010). According to
the forecasts for the year 2030 these values will increase considerably, e.g. due to the fashion
in highly developed countries and the EU initiative aiming at the creation of integrated digital
society (EC COMISSION, 2007).
Figure 3. The structure of the analysed group of respondents in terms of age and Internet use
The need to include issues connected with new information and communication
technologies in the futuristic furniture design and interior design is also indicated by the
analysis of the frequency of Internet use. In the group of respondents aged 40 - 50 years and
51 - 60 years among Internet users 44 % respondents log in to the Internet several times a day,
while in the oldest analysed group this percentage drops to 40 % (Figure 4).
In the conducted analyses it was also decided to collect information on the usage of
touch-screen operated devices. It was shown that 56 % respondents aged 40-50 years and as
little as 14 % respondents aged 61 - 70 use such a mode of operation. This confirms the fact
that with age problems appear in the operation of touch-controlled surfaces, connected with
limited manual capacity of the elderly. Among respondents using such solutions household
appliances ranked second after mobile phones as the most frequently touch-screen operated
products.
Figure 4. The structure of the analysed group of respondents in terms of age and Internet use
frequency
22
WOOD IS GOOD
When analysing consumer preferences concerning the e-trend in kitchen furniture design
the application of modern solutions facilitating the use of different internet applications for
foodstuff purchases, analyses of calorie content of individual dishes or operation of electrical
appliances need to be taken into consideration. It was decided in this study to verify the level
of respondents’ interest in on-line purchases of foodstuffs. Results showed that most
respondents are not interested in this service (68 %). It is of interest that this group includes
also individuals using the Internet at present (Figure 5). However, it is not connected with a
lack of belief in the applicability of Internet solutions in shopping, but first of all a lack of
confidence in the quality of food products offered in Internet shops.
Direct interviews indicated a lack of trust in the quality of thus purchased products
among the individuals not interested in on-line shopping of foodstuffs. They showed distrust
in relation to retailers. It turned out that the respondents prefer personal choices offering a
chance for personal and direct evaluation of quality of a given product and the whole offered
range of products. Results indicate a present-day lack of popularity of the described service in
Poland, which will obviously change in the future. From year to year an increasing interest in
on-line shopping among Poles in relation to products, which so far have not been treated by
many consumers as typical on-line purchase options, e.g. food products may be observed
(FRONTCZAK, 2012). The other respondents consider this offer to be interesting, among which
26 % surveyed individuals at present use the above mentioned service and 6 % would like to
start using this option.
Figure 5. Interest of respondents in on-line shopping
Source: Own elaboration
Modern information and communication technologies are becoming a window to the
world for contemporary users, providing extensive opportunities to follow the press and the
news, listen to music, watch TV or talk or conduct video-conferences with the family, friends
and colleagues. In view of the fact that the kitchen has always been and according to forecasts
will continue to be the centre of the entire house, its design and furnishings should provide it
with a multifunctional character and make it a multimedia centre. The need to create space
with such properties is indicated by the results of an analysis of activities performed by the
respondents when staying in the kitchen. The tasks most frequently performed in the kitchen,
next to the traditional tasks connected with meal preparation (94 %) and consumption (75 %),
should also include listening to the radio, reading newspapers and playing with
children/grandchildren. Respondents also mentioned such activities as watching TV or using
the computer. It needs to be stressed that among computer users in the kitchen as many as
60 % were individuals aged 40-50 years. Thus it may be expected that with an increasing
popularity of IT solutions among the younger generations of users the use of computers also
in the kitchen space will be increasing. The justification for the future transformation of the
kitchen space into a multifunctional room is also indicated by results of studies showing that
23
WOOD IS GOOD
51 % respondents aged 40-50 years would like to combine the kitchen with the dining room,
the living room or another room.
An important stage in the analysis of user preferences was connected with the collection
of information concerning the number of respondents willing to use the kitchen equipped with
modern solutions aiding work in the kitchen, including Internet access. The study showed that
as many as 60 % respondents were willing to buy kitchen furniture designed in the e-trend.
A combination of entertainment, social life and gathering information with basic
activities performed in the kitchen provides the kitchen space with multifunctionality and
confirms the justification for the commonly assumed thesis that it is the heart of each house.
Among trend watchers these activities will not cease and will continue to increase in
importance. It is even possible to move the office to the kitchen space (WANNINGER, 2009).
3.2. Selected solutions of e-trend kitchen furniture design
Analysis of housing needs indicates that in contemporary interiors objects combining
more than one utility function are considered increasingly more desirable. In the future
multifunctional products will gain in importance to an unprecedented degree (S KALSKA, 2010;
EDELKOORT, 2011). According to SMARDZEWSKI (2008), a multifunctional piece of furniture
in contemporary design has gain a new role and new quality, among other things thanks to its
being saturated with electronics and automation, which significantly improves quality,
comfort and safety of its use. Moreover, when presented in modern proportions and design –
in contrast to previous periods – it is associated with luxury and safety. Designing of
multifunctional concepts for kitchen furniture, with strongly integrated and interdependent
functions, has made it possible to apply state-of-the-art technologies characteristic of the type
of the designed e-kitchen.
In relation to the adopted design assumptions a concept of the e-kitchen was established,
within the framework of which original and functional kitchen furniture was designed. In an
ergonomic and intelligent manner it combines several functions, at the same time constituting
a framework case for household appliances and modern technological solutions. The design
project incorporates two types of furniture, a cabinet and a kitchen island, which due to its
controlling functions and household appliances may be considered the centre of the designed
kitchen. Moreover, the island is a centre for three mobile kitchen islands which may be
assembled on its basis, which facilitates the creation of arbitrary arrangements of kitchen
layouts (Figure 6).
Figure 6. Visualisation of the concept of designed kitchen furniture with separate islands
24
WOOD IS GOOD
An important step in the design project was to develop kitchen furniture, which
arrangement would provide the kitchen space the potential for a sterile workplace, in which
all tools would be within easy reach, at the same time providing no obstacle for the smooth
realisation of the user’s tasks. For this purpose a hexagonal shape of the kitchen island was
divided into three identical rhomboid kitchen islands, thanks to which it would be possible to
isolate three basic working areas in the kitchen, such as the washing area, the product
processing area and the thermal processing area (Figure 7).
Providing dynamics to kitchen furniture thanks to the mobility of the islands, apart from
the possibility to create an ergonomic work triangle, makes it possible for users to adopt any
given utility area arrangement in the kitchen. This assumption makes it possible to offer
various arrangements in the kitchen, including space for communal cooking with invited
guests with the possibility to divide it into individual zones, a playground for children or
space for exercise.
While attributing functions to individual islands it was decided to follow opinions of the
respondents concerning the preferred type of lower cabinets and household appliances. In
view of the fact that a vast majority of respondents (61 %) aged 40-60 years would like to
have lower cabinets with drawers and some mentioned drawers as the missing piece of
kitchen furnishings, it was decided to install them in all designed islands.
Figure 7. Visualisation of the concept for the island divided into 3 working areas
In the modern world state-of-the-art solutions are frequently connected with the
elimination of furniture handles or buttons in household appliances, being replaced by touch
panels to control the appliance mechanisms. A popular solution is to apply a touch system
opening drawers in the kitchen space. In view of the results it was observed that the above
mentioned solutions are used by as many as 51 % analysed group of individuals aged 40-60
years. For this reason it was decided to apply them in the proposed solution.
It needs to be mentioned here that a concept for the design of the e-kitchen in the form of
kitchen cabinets composed of five zones: a fridge, a mini-conservatory and a specially
arranged storage space for vegetables, fruits or dishes (Figure 8). It offers a possibility to
arbitrarily arrange storage zones and enlarge them depending on consumers’ needs. An
additional function is connected with lighting under the cabinet segments, which previously
selected and coded colour would identify individual zones for product storage, in a simple
manner signalling the cabinet contents to the user.
25
WOOD IS GOOD
Figure 8. Functionality of the concept for kitchen cabinet
Based on information of users’ preferences obtained during direct interviews it was
decided to design this innovative kitchen cabinet in the form of a traditional showcase. The
visibility of the cabinet contents may be limited or completely obscured thanks to the
interactive fronts. Moreover, an additional task for the interactive fronts would be to provide
multifunctionality of the kitchen space. It may be concluded from the results of the survey
that in modern households the users, apart from the performance of basic activities in the
kitchen, are also involved in leisure activities. When selecting functions which would be
assigned to the kitchen space the results of the questionnaire survey, showing that respondents
most frequently listen to the radio, watch TV and read newspapers in the kitchen were taken
into consideration. The above mentioned functions are served by the tablet mounted in the
kitchen island, which through the digital environment makes possible videoconferencing with
family and friends, medical consultations with doctors or physiotherapists in combination
with exercise. Moreover, entertainment will be provided in the form of films, music and
access to the latest news thanks to such media as television or radio. Moreover, the tablet
mounted in the working surface will make it possible to switch images to a larger screen
found in the pre-selected fronts of kitchen cabinets. The most important applications which
were used in the designed kitchen concern first of all the field of health care, they facilitate
consultations with doctors with no need to leave the house and the most advanced will take
blood pressure measurements and measure blood sugar levels. These solutions due to the
increasing costs of medical care will be valuable and commonly applied in the future. Other
solutions affecting health protection are applications connected with maintenance of physical
activity using a specially prepared exercise programme. The concept of the design also
includes basic applications expected in the kitchen, related with recipes and required products,
i.e. The photo cookbook - Quick&Easy. This e-cook book in a comprehensive manner, using
photographs, presents individual stages of dish preparation shown by an experienced cook.
4. SUMMARY
Interest of respondents in the introduction of modern solutions in the kitchen space, its
mechanisation and computerisation, ensuring user safety, functionality, easy performance of
kitchen tasks and maintenance of cleanliness confirm the advisability of the developed
concept of the e-kitchen. It results from these investigations that the proportions of computer
and Internet users increase in the following groups aged 61-70, 51-60 and 40-50 years. Thus it
needs to be expected that this trend will be maintained in the next years in accordance with
26
WOOD IS GOOD
the growing popularity of IT solutions among young generations in highly developed
countries.
Collected survey results and evaluation of the design phase by the users made it possible
to design the kitchen of the future, perfectly matching the e-trend. Taking into consideration
users’ preferences made it possible to develop a concept corresponding aesthetic preferences
of the analysed group of users and furniture fittings with modern IT solutions improving the
standard of life.
The study focused on the application of state-of-the-art IT and communication
technologies in the design, thus incorporating the latest design trends in this project. A design
of ergonomic, functional and original kitchen furniture was created, facilitating development
of social interactions, motivating to be active and increasing physical activity of the kitchen
users.
Acknowledgements: These examined issues constitute a part of the project: StarDust of the
Baltic Sea Region Programme 2007 – 2013: The Strategic Project in Trans-national
Commercial Activities in Research & Innovation, Clusters and in SME- Networks.
This work was part-financed by the European Union (European Regional Development Fund
and European Neighbourhood and Partnership Instrument).
5. REFERENCES
BATORSKI, D. (2010): Między alienacją a adaptacją. Polacy w wieku 50+ wobec Internetu. Raport
Otwarcia Koalicji „Dojrz@łość w sieci” Warszawa.
BRADLEY, N.; POPPEN, W. (2003): Assistive technology, computers, and Internet may decrease sense
of isolation for homebound elderly and disabled persons. Technology and Disability 15: pp. 19–
25.
EDELKOORT, L. (2011): Design for the future. Compasses 15: pp. 44-53.
FRONTCZAK, J. (2012): Handel internetowy w Polsce 2012. Analiza i prognoza rozwoju rynku ecommerce 2012-2014.PMR Publications, Kraków.
JĘDRZEJCZAK – SPRYCHA, A. (red.) (2011): Konsument przyszłości - kierunki rozwoju wzornictwa
przemysłowego w Polsce do 2030 roku. Raport Instytutu Wzornictwa Przemysłowego w
Warszawie.
KOMISJA WSPÓLNOT EUROPEJSKICH (2007): Komfortowe funkcjonowanie osób starszych w
społeczeństwie informacyjnym. Inicjatywa i2010. Plan działania w sprawie technologii
teleinformatycznych i starzenia się społeczeństwa. Komunikat Komisji Parlamentu
Europejskiego, Rady Europejskiego, Komitetu Ekonomiczno- Społecznego oraz Komitetu
Regionów. Bruksela: COM (2007) 332.
KRISHNAMOORTHY, S. (2001): A smart video assistant for the kitchen. Massachusetts Institute of
Technology, Cambridge, 20-21.
KRZYŻANOWSKA, Ł.; DANIELEWICZ, M. (2010): Mobilny Internet 50+. Nowe media w rękach
starszych użytkowników. Instytut Socjologii Uniwersytetu Warszawskiego.
PALCZEWSKA, I.; BOCHIŃSKA, B.; BRYNDAL, D. (2011): Analiza stanu wzornictwa usług
świadczonych drogą elektroniczną i perspektywy ich rozwoju w Polsce. Raport Instytutu
Wzornictwa Przemysłowego w Warszawie.
QUINN, B. (2011): Design Futures. Merrell, London, 6-7, 42-45, 56-62.
SKALSKA, Z. (2010): Światowe trendy w designie. Czy polskie produkty za nimi podążają? O!to
design. Spotkanie z polskim designem: pp. 20 - 29.
SMARDZEWSKI, J. (2008): Projektowanie mebli. PWRiL, Poznań, 90-101, 112-113, 137-143.
WANNINGER, C. (2009): Laying out the future. Architecrure and Design. Imm Cologne: pp. 87 – 93.
27
WOOD IS GOOD
Influence of Tool Wear on the Quality of the Newly Formed Surface in the
Drilling of Wood Composites
GORNIK BUČAR Dominikaa*– MERHAR Mirana – GOSPODARIČ Bojana
a
Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana, Slovenia
*
Abstract – The geometry of a drilling tool largely affects the quality of the newly formed surface.
When drilling through a composite panel, the hole edge quality on the outlet side is significantly worse
than on the inlet side, so the choice of the appropriate tool geometry is crucial. Even if the tool
geometry is correct, tool wear also has a strong influence on the quality of the newly formed surface of
the holes. With the tool wear, the force in the direction of drilling and torque around the axis of
drilling are increasing which can affect to the delamination of particle board on the outlet side. The
proposed model for hole edge quality prediction on the outlet side was tested on an experimental
model where the cutting forces and torque in the drilling direction were measured, and the quality of
the newly formed surfaces was evaluated every 180 holes using a visual method.
drilling / cutting forces / particle board / surface / delamination / quality of the edge
1. INTRODUCTION
In the furniture industry, furniture is most frequently made from surfaced, composite
panels of medium (MDF) and low (PB) density. The drilling of holes through composite
panels presents considerable problems in the assurance of a high quality edge on the outlet
side of the hole. If the loads involved in drilling the hole through the composite are higher
than the delamination value of the composite, the composite delaminates on the outlet side is
most frequently unacceptable. Drilling loads depend on the technological parameters of
machining, i.e., feed rate, tool rotation speed, tool geometry, and specimen properties. The
structure and composition of the composite in particular have a strong influence on the tool
wear as well.
Today, composite panels can contain a large portion of recycled old furniture, and thus
also contain a relatively great amount of particles that are not of a wood and lignocellulose
origin. Most frequently, these are ground metal structural elements (screws, door hinges,
metal guides, etc.) of the recycled furniture or sand and stones which were introduced into the
composite raw material during transport and handling of waste furniture before the recycling
process. In the event that during the process of drilling the tool comes in contact with such a
foreign body in composite panel, the tool is instantaneously damaged, which considerably
changes the tool geometry and increases the thrust force, consequently affecting the
composite delamination on the outlet side of the hole. In the case of automated production it
is therefore reasonable to use a tool monitoring system, and if the tool is damaged, stop the
production until the damaged tool is replaced.
Many researches have been conducted to determine the optimum technological
parameters of drilling and their influence on the delamination of the layer on the outlet side of
the hole can be found in literature. Most frequently the authors used MDF boards in their
research (VALARMATHI et al., 2012; PAULO DAVIM et al., 2008; GAITONDE et al., 2008 and
PALANIKUMAR et al., 2009). However, in 2013 a study of the analysis of drilling technology
parameters in drilling particleboards (VALARMATHI et al., 2013) was published, where thrust
force was also measured and analysed. The studies take no consideration of tool wear which,
however, strongly and immediately affects the magnitude of thrust force in drilling.
29
WOOD IS GOOD
2. EXPERIMENTAL SYSTEM
The measurements were performed using a three-axis, experimental CNC machine tool in
the Laboratory of Mechanical Processing Technologies at the Biotechnical Faculty of the
University of Ljubljana. The rated power of the tool spindle of the CNC machine tool is 3.2
kW at a nominal speed of 18000 rpm. A clockwise rotating tool intended for drilling holes,
produced by Leitz, with designation 34077, 8 mm in diameter and with maximum drilling
depth of 70 mm was used for drilling into a white, 18 mm thick, laminated particleboard. A
cyclic drilling programme was used to drill series of 180 holes into the panels of 500 mm x
700 mm in size. The distance between holes was 15 mm, the tool feed rate was 1800 mm/min,
and the tool speed was 6000 rpm. After each completed series of drilling, the thrust force was
measured in the direction of drilling axis on the previously prepared five specimens, which
were subsequently also used to determine the particleboard delamination factor. The thrust
force was measured by a three-axis, piezo-dynamometer by Kistler, with designation 7292,
which was connected to a Kistler 5019 amplifier. The amplifier output was connected to a
multifunctional PCI interface with designation NI USB 6351, made by National Instruments,
which made it possible to store force measurements with the sampling frequency of 100 kHz
for further analysis. The measurement system block diagram is shown in Figure 1.
Figure 1. Measurement system block diagram
3. RESULTS OF MEASUREMENT
Equation 1 was applied to determine the particleboard delamination factor for the
specimens used to measure the thrust force. Each specimen was photographed and the area of
particleboard delamination was measured using the photo processing program, which is
shown in Figure 2.
Fd =
dd
d
Fd - delamination factor
dd - diameter of the circle drawn around delamination area [mm]
d - hole diameter [mm]
The results of calculated delamination factors are recorded in Table 1.
30
(1)
WOOD IS GOOD
Figure 2. Graphic presentation of determining the delamination factor
Table 1. The measured composite delamination factor of five test specimens after N drilled holes
N
185
1110
2220
3330
4440
5550
s1
s2
s3
s4
s5
1.00
1.00
1.00
1.00
1.00
1.00
1,21
1,30
1,24
1,00
1,16
1,18
1,24
1,36
1,25
1,15
1,43
1,29
1,31
1,25
1,45
1,22
1,20
1,29
1,44
1,26
1,32
1,22
1,35
1,32
1,28
1,33
1,26
1,35
1,34
1,31
Figure 3 shows the time course of the average of five measured thrust forces which were
measured in five specimens after the completed cycle of drilling 180 holes. However, the time
course of the force, on the assumption of constant feed rate, shows that during the phase of
drilling the force reaches two peaks, and both peaks represent structural properties of
particleboard or its density profile. Thus, the two denser layers on the surface of particleboard
have a greater specific cutting and thrust force. The somewhat lower first peak, as compared
to the second one which is on the outlet side of the hole, can be attributed to the geometry of
the tool used which was intended for drilling holes and therefore had a very small point angle.
The second force peak which is encircled in Figure 3 occurs in the phase of drilling the
bottom layer of particleboard, and in the event that it exceeds delamination value of the layer,
it causes delamination of the particleboard on the outlet side of the hole. Figure 3 also shows
the influence of tool wear on the magnitude of thrust force; i.e., after 5550 drilled holes the
thrust force is increased by 84.2 %. Figure 4 presents the dependence of thrust force and the
delamination factor on the number of drilled holes. The measurements show that the
maximum permissible thrust force which has no influence on the delamination of outlet hole
is 60 N.
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Figure 3. Measured averages of force in the direction of drilling
Figure 4. The course of delamination factor Fd (red) and maximum thrust force F (green) of
drilling depending on the number of drilled holes
4. CONCLUSION
The results of measurements show a relatively good relation between thrust force
magnitude and particleboard delamination factor, which also means that the maximum value
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of thrust force can be used to determine the surface quality on the outlet side of the hole or the
degree of particleboard delamination. It is assumed that similar results can also be expected in
a different evaluation of the particleboard quality or the delamination degree on the outlet side
of the hole and torque around the axis of drilling. The results of preliminary measurements
indicate the possibility of using the thrust force measurement as a starting point in the
regulation of adapting the technological parameters of the feed rate or the rotational speed of
the tool to the optimum, or still the satisfactory degree of composite delamination on the
outlet side of the hole.
5. REFERENCES
GAITONDE, V.N.; KARNIK, S.R.; PAULO DAVIM, J. (2008): Taguchi multiple-performance
characteristics optimization in drilling of medium density fibreboard (MDF) to optimize
delamination using utility concept. Journal of materials processing technology 196: pp.
73-78.
PALANIKUMAR, K.; PRAKASH, S.; MANOHARAN, N. (2009): Experimental Investigation and
Analysis Delamination in Drilling of Wood Composite Medium Density Fiber Boards.
Materials and Manufacturing Processes 24: pp. 1341-1348.
PAULO DAVIM, J.; CLEMANTE, V.C.; SILVA, S. (2008): Drilling investigation of MDF. Journal
of materials processing technology 203: pp. 537-541.
VALARMATHI, T.N.; PALANIKUMAR, K.; SEKAR, S. (2012): Modelling of thrust force in
drilling of plain medium density fibreboard (MDF) composite panels using RSM.
Procedia Engineering 38: pp. 1828-1835.
VALARMATHI, T.N.; PALANIKUMAR, K.; LATHA, B. (2013): Measurement and analysis of
thrust force in drilling of particle board composite panels. Measurement 46: pp. 12201230.
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Increasing the Productivity of Enterprises with the 20 Keys Method
GRLADINOVIĆ Tomislava – PERIĆ Ivanaa*– STASIAK-BETLEJEWSKA Renatab – ŠKODA Petara
b
a
Wood Technology Department, Faculty of Forestry, University of Zagreb, Zagreb, Croatia
Institute of Production Engineering, Faculty of Management, University of Technology, Poland
*
Abstract – Each production has its own specifics. These depend on many variables of both global and
local character (e.g. global: roads, proximity of mills and forests, etc., local: availability of staff and
necessary connections, production space, machines, etc.). All these particular characteristics affect
production to a different extent. The role of managers is to put them all in balance, i.e. to create the
most suitable climate for the development and growth of their company, production or trade. For
quality problem-solving, the state of all production processes must first be determined, because only a
systematic and realistic identification of problems results in long-term success. Wood-processing
industry requires a very deep understanding of a specific problem and a cautious approach. The
research polygon for this study was a furniture manufacturing enterprise, in which time and material
flow were monitored and workplaces involved in the production process examined. Based on that, a
proposal was put forward with solutions for improving the enterprise productivity. As a guide through
the reengineering method, the 20 Keys Method was used.
furniture manufacturing / wood processing / the structure of time / flows of materials /
reengineering / 20 keys method
1. INTRODUCTION
Reengineering is defined as the fundamental rethinking and radical redesign of
production and business processes to achieve improvements in the effects related to costs and
business quality (HAMMER – CHAMPY, 1994). This definition reconsiders businesses in a new
way with the aim of remaping dramatic improvements in business performance and
measuring business performance indicators. These indicators are designed for end user and
focus on them. Reengineering radically changes some traditional ways of process
improvements.
From the standpoint of business strategy, reengineering claims to optimize the
performance of administrative and supportive processes, as well as optimize the performance
of operative processes. The goal is to achieve competitive advantage and switch the nature of
competitive struggle towards changing the industrial structure in the direction favourable for
an enterprise. The innovative potential of information technology and a better use of human
potential provide the main sources of competitive advantage; hence, they play a crucial role in
reengineering.
The introduction of reengineering requires from individuals and working teams to
perform the majority of business processes independently; in other words, all their know-how
and skills are fully engaged. For this reason, employees enjoy the rights which in a traditional
organisation are given only to managers. It should be emphasised that reengineering requires
a different approach to employee treatment. The employees are treated in a „more relaxed“
manner, there is no pressure on them and their achievements are highlighted and awarded, all
with the goal of enhancing their creativity and thinking and making them the key generators
of ideas and innovations. An enterprise is public-oriented rather than closed in its own
business and production frames. Reengineering refutes processes which, either directly or
indirectly, do not create value-added products (degree of customer satisfaction).
According to FIGURIĆ (2000), the central place in the reengineering philosophy is given
to processes. Thus, a company's approach to processes and more superior organisation is
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WOOD IS GOOD
primarily prompted by the fear of their competitors' „catching up with and outrunning them“.
The globalisation of furniture markets, the rapidly changing world, the ever more demanding
customers and increasing competition constantly drive companies to reconsider their business
operations.
2. THE 20 KEYS METHOD
One of the reengineering methods is the 20 Keys Method. Created by Iawo Kobayashi of
Japan and based on the Toyota production system, this programme of measures is geared
towards permanent business development. The 20 Keys Method has been adopted by more
than 500 companies worldwide (e.g. Sanyo, Gillete, Seiko), including some companies in the
neighbouring countries. This method consists of very simple measures which business
systems should apply in practice. The keys and tasks are presented in the form of advice,
which, implemented and adhered to lead to a higher organisational level and diminish the
needs of production resources, at the same time increasing the efficiency.
Key 1 The task is to clean and organize a workplace (Table 1). At first sight, this is an
absurd advice. However, a more careful examination of companies shows that this first key is
absolutely necessary. Order is the condition of making work easier, but in a large number of
cases it has not been achieved.
Key 2 Rationalizing the System, Goal Alignment. A clear and well organized goal
alignment system is the key to efficient guidance. This is what Key 2 is all about. Particular
emphasis is put on team work and guidance towards the goal, as it integrates the interests of a
company and an individual.
Key 3 Small Group Activities. Work in small groups enhances innovations, increases
company adaptability and strengthens readiness to participate. This is why Key 3 leads to
better efficiency and success.
Key 4 Reducing Inventory. Major savings can be made in the field of inventory and
products reductions. Key 4 envisages improvements in this field.
Key 5 Quick Changeover Technology. Adaptability is the key to survival. Changeover
technology is a must in this field. However, organisational conditions to reach this goal are
often neglected. This is why Key 5 advises savings by shortening production cycles.
Key 6 Manufacturing Value Analysis. Cutting down on unnecessary tasks and on work
that does not add to product value saves time and other resources needed for useful work. This
is why this Key proposes value analysis in order to eliminate superfluous work.
Key 7 Zero Monitor Manufacturing. Monitoring and supervision is unproductive work
per se. If eliminated without any harm, we have done a useful act. Although not completely
possible with systematic work, it can still be achieved to a great measure.
Key 8 Coupled Manufacturing. Coupled manufacturing is easier to plan, supervise and
guide. This is why the goal of a good organization is to achieve coupled manufacturing. Key 8
proposes a method of linking production processes and decreasing inventories.
Key 9 Maintaining Machines and Equipment. Maintaining machines is the core condition
of continuous production. It is not surprising therefore, that Key 9 proposes exactly this.
Preventive maintenance will allow for easier accomplishment of production processes.
Key 10 Work time Control. Work time control is an important factor in every production
and business process, and this is why it requires particular attention. Efforts are geared
towards full use of work time, as suggested by this Key.
Key 11 Quality Assurance. Quality assurance is the key to success. This is why the Key
suggests a set of tasks intended to eliminate mistakes and increase self-control.
Key 12 Developing Supplier Cooperation. A supplier is not a partner. A partner
participates in business results; hence, the relationship between partners is more intimate and
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responsible. Rationalization of the suppliers' production processes directly benefits the
customer. Key 12 is all about this issue.
Key 13 Eliminating Wasteful Human Activities. Perform only those activities that
increase value and decrease resource use. Every unnecessary activity is irrational. This Key
expands this idea to the entire business and not only to the product referred to in this Key.
Key 14 Empowering Employees to Make Improvements. Improved rationalization should
not be in theory only. Employees should be trained to introduce improvements.
Key 15 Skill Versatility and Cross Training. Production will be more versatile if
employees are trained to perform different tasks. It will also be possible to deploy them to
different workplaces. This requires additional training.
Key 16 Production Scheduling. Planning is given particular attention. This is
understandable, since planning entails predicting the events and avoiding mistakes.
Key 17 Efficiency Control. Efficiency control is the condition of success. It forms the
basis for a motivation and stimulation system and enables more efficient and realistic
planning.
Key 18 Using of IT Systems confirms that the introduction of microprocessors enhances
rationalisation.
Key 19 Conserving Energy and Materials. It is not surprising that conserving energy and
materials enhances rationalization.
Key 20 advises the implementation of Leading Technologies, provided that the
guidelines contained in the keys described above are on the required developmental level and
degree. Otherwise, there may easily be negative effects (HAMMER – CHAMPY, 1994).
Table 1. Cleaning and Organising to Make Work Easy (HAMMER – CHAMPY, 1994)
Key 1
Level 1
Characteristic
Cleaning and Organising to Make Work Easy
Level 2
Level 3
Level 4
Level 5
Characteristic
Characteristic
Characteristic
Characteristic
Transport routes
are free. The tools
are still visibly
scattered around.
The machines and
equipment are
clean. The storage
spaces are defined
and organized.
Cleaning is done
regularly and
constantly.
Workplaces are
clean and the
tools are stored
and clean.
Step up to a
higher level
Step up to a
higher level
Step up to a
higher level
Step up to a
higher level
Check all the
spaces. Check the
workplaces and
remove all litter,
superfluous tools
and materials.
Check all the
walls and put
away litter and
superfluous tools
and materials.
Check the
drawers and
cabinets and sort
out the tools and
other items. Do
not lock the
offices.
Regularly tidy up,
clean and keep
your workplace in
order. Visually
check the tools
and inventory.
Important
steps
Important
steps
Important
steps
Important
steps
Do not store
things on the
floor. Discard all
the things you
know you will not
need.
Share the
responsibility for
order. Make it
clear that
employees are
responsible for
the cleanliness of
their workplaces.
All things should
be immediately at
hand. The
frequently used
tools should be
easily accessible
and other tools
should be put
away.
Introduce an
experimental line,
but the workplace
with parts and
tools should be
arranged on a
self-service
principle.
Cigarette butts,
rolls of paper and
tools are scattered
around.
Litter and
different items are
scattered on the
floor and walls.
Transport routes
are not free.
Step up to a
higher level
Important
steps
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3. REENGINEERING OF THE STUDIED PLANT USING THE 20 KEYS METHOD
After careful data examination and analysis of the condition in the observed plant, the 20
Key Method was proposed with the goal of improving productivity and launching a
competitive assault on the market, since this method systematically and favourably affects all
manufacturing processes. Improvement is achieved by following the keys that determine the
characteristics of different levels (from the poorest 1 to the best 5). Based on these levels, the
climb to a higher level is suggested and important steps are made into higher levels of
business production.
Key 1 Cleaning and Organizing the Workplace. Level 2 was detected – different items
scattered across the workplace. Transport paths are not free. Workplaces should be examined
and all unnecessary items, materials and tools should be put away. An important step is to
share the responsibility for order and make it clear to the employees that they are responsible
for their workplaces.
Key 2 Organizing the System, Goal Alignment. Level 2 was found – the organisation is
clear, but the tasks are set down imprecisely. Goals should be set and decisions made on who
should do what and how. Clear goals should be made to match the level that corresponds to
the department, stage of work or an individual.
Key 3 Small Group Activities. Level 1 was detected - there is no willingness to work in
groups. A formal system of improvement adoption should be implemented. Proposals should
be rewarded and the importance of joint employee effects per group should be emphasised.
Key 4 Reducing Inventory. Level 3 was detected – inventories are being reduced (but not
sufficiently). All the machines and lines should be rearranged (related to technological
processes for room doors, wardrobes and kitchens), and production should be organized so
that fewer interphase inventories are needed. An important step involves the introduction of a
material ordering system and simplifying of semi-finished products.
Key 5 Quick Changeover Technology. Level 2 was detected –responsible employees
understand the importance of quick tool change. Participation at all levels should be
encouraged and methods of achieving systematic improvement should be implemented.
Key 6 Manufacturing Value Analysis. Level 3 was found – in some processes
improvements are being systematically prepared. A plan of implementing improvements
should be drawn up and documentation for an organized approach to improvements should be
prepared. An important step involves setting the goals to shorten manufacturing time.
Key 7 Zero Monitoring Manufacturing. The plant was found not to posses the machines
needed to implement Key 7.
Key 8 Coupled Manufacturing. Level 2 was detected – the importance of continuous,
integrated production is understood. Strategies to integrate production should be developed
and studied. An important step involves reducing the inventories and controlling them in
order to enable coordinated activity.
Key 9 Maintaining Machines and Equipment. Level 1 was found – machines operate
until they break down. Preventive machine maintenance should be introduced. Important steps
involve detecting and singling out the machines that affect production flows most and prepare
checking lists for preventive maintenance.
Key 10 Work time. Level 1 was detected – work time and rest periods are left to
employee discretion. The beginning of work time should be determined by e.g. introducing
morning meetings. Meetings should be well prepared and purposeful.
Key 11 Quality Assurance. Level 2 was detected – workers control their products.
However, one of the characteristics of a particular type of production is that every
manufactured part is “tested”, which requires setting the machine for every part individually.
Accordingly, quality assurance is at level 4. It should be pointed out that effort should be
directed towards establishing a system of eliminating mistakes.
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WOOD IS GOOD
Key 12 Developing Supplier Cooperation. Level 5 was found – the supplier becomes a
partner in the proper sense of the word.
Key 13 Eliminating Wasteful Human Activities. Level 1 was found – there is no
awareness of the importance of detecting superfluous work. It should be made clear to the
employees that effort without effect is meaningless and represents a waste of time. Only those
operations which the customer is ready to pay for should be performed.
Key 14 Empowering Employees to Make Improvements. Level 2 was found – it is
possible to prepare minor improvements. It would be important to accept the fact that the 20
Keys Method increases the available space for company innovations.
Key 15 Skill Versatility and Cross Training. Level 5 was detected – the company freely
deploys employees, thus successfully meeting environment demands.
Key 16 Production Scheduling. Level 1 was detected – terms of deliveries are not
obeyed. Production should be planned and orders followed. It is important to set down the
time needed for production.
Key 17 Efficiency Control. Level 1 was detected – an indirect system of efficiency
control is in use. The necessary number of operations and times per group of products should
be determined. Groups of products should be shaped according to the number of type of
operation.
Key 18 Implementing IT Systems. Level 2 was detected – computers are used for simple
jobs. The importance of microprocessors should be enhanced. The employees should be
trained to use microprocessors and computers.
Key 19 Conserving Energy and Materials. Level 2 was found – the employees are aware
of the importance of saving energy and materials. Some obvious savings should first be made.
The awareness that knowledge is the key to success is very important.
Key 20 Implementing State-of-the-Art Technology. Level 2 was detected – the company
does not have the possibility to implement new technologies. The financial construction
should be closed and programmes of technology development proposed. It is important to
coordinate technology development with product development.
4. CONCLUSION
The 20 Key Measures and Methods have been implemented in the studied plant with the
goal of improving and optimizing production. Guidelines for further growth and development
of production and business have been installed.
Manufacturing processes in the company were analysed and a solution was made by
setting a clear organisation of the company’s mission and vision through a business and
production function. Examination of the current state of the company revealed low levels of
the majority of business standpoints. It is difficult to analyse manufacturing with traditional
methods, which are formulated for serial industrial and mass production systems. The reasons
for this are found in the characteristics of the observed manufacturing plant. This is the reason
that plant reengineering is proposed to address decision-making processes, whereby the 20
Keys Method would constitute the main reengineering tool.
The procedures and methods of increasing productivity that are developed at given
entries and presented in the subject material make it possible to achieve considerable
improvements and better effects through systematic work.
5. REFERENCES
BIZJAK, F. (1994): Inovativno vođenje in gospodarenje podjetja. Univerza v ljubljani, Biotehniška
fakulteta, Oddelek za lesaravo, Ljubljana.
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WOOD IS GOOD
BIZJAK, F. (1997): Reinženjering in razvoj podjetja. Educa, Nova Gorica.
BIZJAK, F.; PETRIN, T. (1996): Uspešno vođenje podjetja. Gospodarski vestnik, Lubljana.
FIGURIĆ, M. (1987): Organizacija rada u drvnoj industriji. Narodne novine, Zagreb.
FIGURIĆ, M. (2000): Proizvodni i poslovni procesi u preradi drva i proizvodnji namještaja. Šumarski
fakultet Sveučilišta u Zagrebu, Zagreb.
FIGURIĆ, M. (2003): Menadžment troškova u drvnotehnološkim procesima. Šumarski fakultet
Sveučilišta u Zagrebu, Zagreb.
GOJANOVIĆ, J., (1977): Ekonomika i organizacija proizvodnje. Informator, Zagreb.
HAMMER, M.J.; CHAMPY, J. (1994): Reengineering corporation. Harper Business, New York.
TAKEDA, H. (2006): The Synchronized Production System. Kogan Page, London, Philadelphia
ZELENOVIĆ, D. (1973): Proizvodni sistem. Naučna knjiga, Beograd.
ZELENOVIĆ, D.; RADLOVAČKI, S. (1984): Program za rast produktivnosti. FTN-Institut za industrijske
sisteme, Novi Sad.
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Kitchen Furniture - Accessibility of Storage and Working Space
HROVATIN Jasnaa*– VIŽINTIN Jožeb
a
Faculty of design - associated member of University of Primorska, Ljubljana, Slovenia
b
University of Ljubljana, Faculty of Mechanical Engineering, Ljubljana, Slovenia
*
Abstract – The number of senior citizens is rapidly increasing. According to statistical prognoses,
36 % of world population will be older than 60 years by the year 2030. The share of people older than
80 years will increase to 11.4 % by 2050. We were interested in the suitability of commercially
affordable furniture for the needs of the elderly, because a comfortable apartment is particularly
important for the elderly who spend most of the time in their homes. The aim of this study was to
determine to what extent kitchens manufactured are suitable for elderly people regard to the
accessibility of goods stored in the cupboards. The study was carried out using a computer simulation
model. The results show that the efficacy of the volume in wall cabinets is not optimal for the elderly.
Also problematic are the height and depth of the kitchen counter. Due to the large differences between
male and female height and between races it is impossible to determine the optimal dimensions of the
elements, since the size of kitchen elements is closely related to the size of the people. Based on the
measurement analysis, we will show same proposals how to improve the kitchen furniture for the
elderly people.
furniture / dimensions / ergonomics / kitchen / elderly / design
1. INTRODUCTION
Higher standard, nutrition and well regulated health care enables a high increase of the
share of the elderly each year. According to statistical prognoses, 36 % of world population
will be older than 60 years by the year 2030 (HILDERBRAND, 2002). This sets completely new
demands for residential and public facilities. The decrease of the birth rate and the mortality
rate are also changing the age structure of Slovenians.
In the field of furniture designed for elderly are very important anthropometry and
ergonomics. Few studies have focused on the correlation between ergonomics and kitchen
furniture design for the elderly. Some authors (HROVATIN, 2002; TRAJKOVIĆ – PREKRAT,
2002; PISSAREVA – JIVKOV, 2009) have addressed the issues of kitchen design by means of
inclusive design, which generally includes the elderly and special needs individuals.
KIRVESOJA et al. (2000) have found that the elderly have greater difficulty in adjusting to
inappropriately high worktops than people under the age of 65. The fact is that kitchen work
could be significantly eased with the appropriate design and suitable arrangement of kitchen
cupboards. In designing kitchens, the optimal depths and heights of worktops and storage
places should also consider accessibility and spinal load.
PENNATRHUR and DOWLOING (2003) state a limit of vertical accessibility of 180 cm. Of
course, accessibility of wall cabinets is lower if a person is standing in front of low cupboards
on the floor or by the kitchen worktop. Accessibility also depends on the size and the age of
the user. The optimal storage zone is between 800 and 1100 mm. Both visibility and
accessibility are reduced at heights between 1400 and 1700 mm. At this height, the majority
of men and women are able to store light items on the edges of shelves, however, accessibility
above 1700 mm is considerably reduced for most people. Apart from height, the depth of the
cupboards and cabinets plays an important role in accessibility and visibility. Pheasant
recommends that the depth of shelves at heights between 800 and 1400 mm should not exceed
600 mm. At heights below 800 mm, the depth of the shelves should be up to 450 mm and at
heights above 1400 mm, the depth should be up to 300 mm (PHEASANT – HSDRIGRAVE, 2006).
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WOOD IS GOOD
PHEASANT (2006) state that a shelf depth of 300 mm and height of up to 1400 mm are
suitable for 95 % of the elderly. Nevertheless, if there is an obstacle in front of the cupboard,
like a worktop, the height should not exceed 1350 mm. Shelves placed below 300 mm are not
suitable for people who have problems kneeling or bending (KIRVESOJA et al., 2000) Deep
shelves are particularly impractical, and the author suggests that shelves be placed above a
height of 500 mm for the elderly.
The elderly have greater problems in reaching objects than younger people (PANERO –
ZELNIK, 1979), due to the occurrence of arthritis and other conditions that restrict joint
movement. Also, elderly users have reduced muscular strength and joint mobility due to the
ageing process. To the greatest possible extent, the majority of items should be stored
between the knuckle and shoulder heights so that elderly users are not subjected to bending
and overreaching demands (KOTHIYAL – TETTEY, 2001). Anthropometric evaluation of
vertical accessibility in a standing position for British adults shows that accessibility between
the young and the elderly differs by an average for 170 mm for males and 147 mm for
females. The difference until the age of 80 is considerably smaller, namely, 120 mm for males
and 80 mm for females.
An article from PENNATHUR et al. (2003) described the functional limitations of the
elderly. Objects in wall cabinets in their kitchens could be reached without difficulty or
assistance by 26.67 % of females involved in the research, with assistance by 56.67 %, while
16.67 % of females could not reach the objects. In the low cupboards, 12.9 % of females did
not have problems reaching the objects, 35.48 % of females were able to reach the objects
with assistance, whereas 35.48 % of females found the objects in the low cupboards almost
unreachable. Accessibility of food in the refrigerator is better, since 87.1 % of females did not
have any problems, 9.68 % required assistance and for 3.23 % of females, the food was
almost unreachable. For this reason is recommended that, it is better to use a lower percentile
(5th percentile) in order to accommodate as large a share of the population as possible.
A 900 mm high worktop is too low for about half of the females and almost all males,
which is why work in the kitchen is often related to pain. (PHEASANT – HSDRIGRAVE, 2006)
Nevertheless, a higher worktop means that wall cabinets should be placed higher, making the
upper shelves even more difficult to reach, especially for the elderly. Furthermore, it is
necessary to consider that the height of the elderly is getting smaller over time. Therefore, the
height of the worktop for the elderly should be lower than for young people.
The objective of this study was to determine the extent to which kitchen furniture
manufactured by the Slovenian furniture producers is suitable for users of different age groups
and the accessibility of objects in the wall cabinets. Furthermore, basic principles upon which
kitchen furniture should be designed to meet the needs of the elderly are proposed based on
the measurement analysis, so as to enable maximal productivity with minimal time and
energy consumption without harmful consequences for health.
According to our analysis Slovenia does not have manufacturers of standard furniture for
the elderly people. Orders for individual clients carry small carpenter’s workshops. In this
paper we present some results of our analysis. Based of the analysis results we will show
same proposals how to improve the kitchen furniture for the elderly people.
The research was carried out using a computer simulation model. 3D modelling
technology is already being integrated into the design of other products (MIJOVIĆ et al.,
2008). A similar research was also carried out by SMARDZEWSKI (2009). A standardised
kitchen furniture manufacture was included in this study and one typical kitchen set was
selected. The 3D CAD programme (MegaCAD, manufacturer MegaTECH and Megatischler
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manufacturer Planles, version 2009) was used to design the kitchen furniture as life-size
furniture. In the study, the focus was on the accessibility of objects in the wall cabinets.
Accessibility was tested using a person designed in three sizes. The data for males and
females of three age groups (19–25 years, 26-45 years and 45–65 years old) was used in
determining sizes. The model person was placed into the kitchen designs and we detected
height accessibility in the wall cabinets (Figure 1). The model was placed beside the worktop
so that the end of the foot was 30 mm from the line of the low cupboard base.
Figure 1. 3D model of a person and the kitchen furniture
3. RESULTS
Using the computer simulation model of a person and the kitchen furniture, we observed
the intersection of accessibility in wall cabinets for different male and female age groups in
the selected kitchen. In Figure 2 the area of accessibility is hatched and in Graph 3 the
calculation of accessibility is presented as a percentage.
Figure 2. Placement of the female and male models, ages 19–65
Female, 19–45 years
Area of
accessibility
(dm²)
4.9
4.7
21.7
21.7
Male, 19–45 years
11.0
21.7
50.7
Male, 45–65 years
9.4
21.7
43.3
50 %ile
Total area
(dm²)
Accessibility
(%)
21.7
22.6
43
WOOD IS GOOD
Figure 3. Accessibility in wall cabinets
Height accessibility depends on the height of the wall cabinets and the distance of the
wall cabinet’s lower edge from the floor. This dimension depends on the height of the
worktop and the height of the interspace between the worktop and the bottom of the wall
cabinet. The interspace is 536 mm. The height of the space between the worktop and the
bottom of the wall cabinet depends on the high cupboards if the top of the high cupboard is
intended to be at the same level as the top of the wall cabinet. Nevertheless, it is desirable that
the height of the interspace is larger so that the wall cabinets do not obscure the view on the
workspace, while on the other hand, the height should not be too high due to accessibility of
the objects in the wall cabinets.
Graph 3 shows that the height accessibility is lower for the elderly than for young people
as a result of decreasing height in the elderly. It should also be noted that if the worktop is
placed at a higher level, the wall cabinets are moved higher, which will, again, reduce
accessibility. If we consider the recommendation of (PISSAREVA – JIVKOV, 2009) that the
recommended height of the worktop is from 80–100 mm measured under the curved elbow,
we can see that the worktop is too low for both males and females.
Figure 4 shows accessibility with the height of the worktop as found in tested kitchen,
and the height accessibility if we adapt the height of the worktop to the height of the users,
namely to 50 % of males and females (Table 1). If the height of the worktop is adapted to the
height of the user, the difference in height accessibility between males and females is
decreased, although males are on average taller than females (Table 2, Figure 5).
Figure 4. Height accessibility for females and males, ages 19–45 in test kitchen (a, c), where the
height of the worktop meets ergonomic requirements (b, d).
Table 1. Accessibility at the height of the worktop that meets ergonomic requirements
50 %ile
Male, 19–45 years
44
Area of accessibility
(dm²)
3.6
Total area
(dm²)
21.7
7.1
21.7
Accessibility (%)
16.6
32.7
WOOD IS GOOD
Table 2. Difference in accessibility concerning the height of the worktop and gender
Accessibility at the height of
the worktop in tested kitchen
(%)
22.6
50 %ile
Accessibility at the height of
the worktop that meets the
ergonomic requirements (%)
16.6
Male, 19–45 years
50.7
32.7
Difference in
accessibility between
man and women
28.1
16.1
Difference (%)
6
18
Figure 5. Graphical display range depending on the amount of counter and gender
3.1. Same proposals for improving design
Considering the results of analysis we have designed same kitchen furniture elements for
people which are older than 65 years. In the interdisciplinary design group designers,
architects, mechanical engineers, electric engineers, wood engineers and ergonomics experts
have taken active part. As a result of the work different kitchen elements for the elderly were
designed with personal security and the ability to perform kitchen tasks faster and more easily
in mind.
Figure 6 shows the solutions how to solve the problem with the kitchen dishes which are
located higher than 150 cm or lower than 65 cm.
Figure 6. New proposal for kitchen elements design
The optimal storage zone is between 800 mm and 1100 mm (PENNATHUR – DOWLING,
2003) thus in the area of the worktop which is without cabinets, as in standard kitchen
furniture the cupboards are positioned under the worktops and above as wall cabinets. The
solution to this problem is high cupboards or cabinets placed on a deeper worktop. Figure 7
shows accessibility in a cabinet placed on the worktop with a body inclination of 30° and 55°.
45
WOOD IS GOOD
Figure 7. Placement of the female model, ages 19–45, in kitchen, with a body inclination of 30° and
55°
Since the cupboards under the worktop are deeper, the volume of these cupboards is 48 %
greater, meaning that by increasing the depth of these cupboards, the storage space has
increased. Nevertheless, considering that the elderly commonly have problems with bending
and kneeling, shelves placed below 300 mm should be avoided, and deep shelves are
especially impractical (KIRVESOJA, 2000). A better solution would be cupboards with drawers
that can be fully pulled out or with lift drawers.
With cabinets placed on the deeper worktop, additional storage space with good
accessibility has been acquired. Accessibility is increased by 70 % if the body is inclined
forward by 30° and by 91 % if the body is inclined by 55°.
4. DISCUSSION
Accessibility is higher for males than for females, which is logical due to differences in
their body heights. On the other hand, accessibility in the wall cabinets also depends on the
height of the cupboards under the worktop and the distance from the lower edge of the wall
cabinet from the floor. If the height of the worktop is adapted to the height of the user, the
wall cabinets are placed higher and the difference in height accessibility is no longer as
prominent (Figure 5).
This study has shown that in wall cabinets higher than 600 mm, the efficiency of the
volume where objects are easily accessible is less than 30 % for females. The percentage is
even smaller if the height of the worktop is 100 mm under the curved elbow, meaning the
space in the wall cabinets is used inefficiently, especially if the wall cabinets are higher.
The results coincide with the results of a study (PHEASANT – HSDRLGRAVE, 2006) that
found that accessibility is reduced at heights between 1400 and 1700 mm. Since the lower
edge of wall cabinets is usually above 1400 mm, this means that wall cabinets are problematic
in terms of comfortable accessibility. It is evident in the figures showing a 3D model of a
person that accessibility on the lower shelf is satisfactory, whereas the objects stored on the
second shelf are difficult to reach.
Accommodation for the elderly should take their physical and emotional characteristics
into consideration. Muscle strength decreases by 40–50 % between the ages of 40 and 80
(KIRVESOJA, 2000). The changes in muscle function are even more apparent after the age of
70. Besides this, the majority of the elderly cannot actively carry out plantar flexion in their
ankle (tiptoeing), which results in even lower height accessibility. In comparison with young
people, the area of comfortable accessibility is decreased for the elderly due to their reduced
musculoskeletal abilities. That is why it is even more important for the elderly to have
46
WOOD IS GOOD
ergonomically designed equipment, which considers anthropometry and enables comfortable
accessibility. It is even more important for the elderly than for young people to have kitchen
furniture that is especially designed to meet their needs. We believe that the cabinets placed
on the worktops are undoubtedly a better solution for the elderly than wall cabinets, since the
accessibility in the wall cabinets is even lower for the elderly than for people up to the age of
45. Therefore, we believe that cabinets placed on a deeper worktop are for the elderly much
more suitable as wall cabinets, the solution also represent a drop-down shelves.
5. CONCLUSIONS
Most elderly who would like to renovate their kitchen in order for it being used for the
rest of their lives, do not have adequate supply in the market. The kitchen furniture produced
by the Slovene manufacturers is not suitable for the elderly. This study has shown that the
efficiency of volume, where objects are comfortably accessed in the wall cabinets higher than
600 mm, is lower than 30 % for females, indicating that the storage space in the wall cabinets
is used inefficiently. The study conclusions are as follows:
- Objects stored in the wall cabinets higher than 600 mm are accessed with difficulty
and therefore a version of the kitchen furniture with deeper worktops and cabinets positioned
on the worktops is recommended if the room size enables such a solution. Good solution is
also a drop-down shelf.
- Cupboards placed under the worktop should have drawers that can be fully pulled out
or lift drawers that allow for a better view of the displayed objects, easier loading and
emptying without having to remove other objects, better efficacy of volume and loading and
emptying without the need for bending.
- Incorporate the intelligent technology a much as possible.
6. REFERENCES
HILDERBRAND, H. (2002): Für Ältere und Behinderte. BM 57. (3): 36.
HROVATIN, J. (2002): Ergonomics in the kitchen – Theory and practice, International symposium
. “Wood is good – Furniture, human, design”. Croatia, Zagreb, oct, 2002. pp. 51-58.
KIRVESOJA, H.; VÄYRYNEN, S.; HÄIKIO. (2000) Three evaluations of task-surface heights in elderly
. people's homes. Applied Ergonomics 31. (4): pp. 109-119.
KOTHIYAL, K.; TETTEY, S. (2001): Anthropometry for Design for the Elderly. International Journal of .
. Occupational Safety and Ergonomics. 7. (1) pp. 15-34.
MIJOVIĆ, B.; UJEVIĆ, D.; BAKSA, S. (2001): Visualisation of anthropometric measures of workers in
.
computer 3D modelling of work place. Collegium Antropol. 25. (1): pp. 639 – 650.
PANERO, J.; ZELNIK, M. (1979): Antropološke mere i enterier. Novi Dani, Beograd, 1979.
PENNATHUR, A.; DOWLING, W. (2003): Effect of age on functional anthropometry of older Mexican
. American adults: a cross-sectional study. International Journal of Industrial Ergonomics, 32. (1):
. pp. 39-49.
PHEASANT, S.; HSDRLGRAVE, C.M.; (2006): Bodyspace, Antropometry, Ergonomics and the Design of
. Work. Third edition. London, Taylor and Francis 332.
PISSAREVA, E.; JIVKOV, V. (2009): Kitchen furniture design for people with physical disabilities,
International symposium. “Wood is good – new materials, quality and design of products”. Croatia,
Zagreb, Oct, 2009. pp.85-90.
SMARDZEWSKI, J. (2009): Anthropotechnical aspects of furniture design. Drvna Industrija, 60 15
TRAJKOVIĆ, J.; PREKRAT, S. (2002): Furniture for mobility-impaired persons, International
. symposium “Wood is good –Furniture, human, design”. Croatia, Zagreb, oct, 2009. pp. 111-120.
47
WOOD IS GOOD
Study on the Gluing Abilities of Solid Surface Composites with Different
Wood Based Materials and Foam PVC
JIVKOV Vassila*– SIMEONOVA Ralitsaa – MARINOVA Assiaa – GRADESVA Galinaa
a
Department of Interior and Furniture Design, University of Forestry, Sofia, Bulgaria
*
Abstract – The present study is related to the gluing abilities of solid surface composites with
different wood based materials and foam PVC boards. Acrylic based solid surface material with
thickness of 6 mm were bonded to five types of different substructure materials – laminated and non
laminated particleboards, plywood, MDF and foam PVC boards. Three types of adhesives were used –
one component polyurethane, rubber based and PVAc. The test has been done according to BDS EN
205. The results show that the type of adhesive and the type of the material of the substructure have
significant influence on the adhesion strength. The highest measured tensile shear strength was
achieved by rubber based adhesive and substructure from plywood. As a substructure the highest
abilities for gluing have wood based materials. For PVAc adhesive with wood based materials as
adherent, different from BDS EN 205 test method should be used.
solid surface composites / gluing abilities / adhesion tensile shear strength / wood based materials
1. INTRODUCTION
Solid surface is a generic name given to a polymerised decorative surfacing material.
Solid surface material has been invented by DuPont™ in the 1967 and is known as Corian®. It
is a solid, non-porous, homogeneous surfacing material composed of ±1/3 acrylic resin (also
known as PolyMethyl MethAcrylate or PMMA) and ±2/3 natural minerals. The main mineral
is Aluminium TriHydrate (ATH) derived from bauxite, an ore from which aluminium is
produced. Aluminium Trihydrate is a common primary ingredient present in most solid
surface materials and accounts for as much as 70 % of the total product. In the last decades
solid surface material became well known and very popular and is generally made, but not
limited to, using an acrylic or polyester resin as bonding agent. Such materials are made in a
variety of nominal thicknesses, for example 3, 4, 6, 8, 10, 12 mm etc. depending on the type
of applications and market requirements. Due to their properties solid surface materials have
many advantages: moisture resistance, resistance to household chemicals and boiling water,
safe for food contact, seamless joints, surface is renewable, easy to clean, thermo formable,
colourful, non-toxic and etc. That is why it is an advanced composite product used as a
decorative material in a variety of residential and commercial applications. Solid surface
material offers design versatility, functionality and durability.
Solid surface composites are widely used in furniture. As a decorative surface material
they are glued to a substructure which could be wood based material or plastics. Typical
application of this kind of sandwich panel is kitchen worktops or bathroom worktops. Another
possibility is a combination of a different structural materials and one of them is solid surface
material. Recommendation of the manufacturers is when the solid surface material has to be
glued to a substructure made of MDF or plywood to be used flexible silicone, rubber based or
polyurethane elastic adhesive. This is because of different thermal expansion of the materials.
Many studies have been done in the field of bonding strength of wood and wood-based
materials. Some of them were investigating the type of testing (KONNERTH et al., 2006;
KYUCHUKOV , 2010). The test for bond strength of scarf joint and lap, as well the joint testing
method for beech and spruce solid wood shows different type of failure with different test
methods (KONNERTH et al., 2006). The failure mode with standard lap joints is mainly wood
49
WOOD IS GOOD
failure and scarf joint failed in the bond line. Predicting of shear strength of test specimens of
wood adhesive bonds have been studied by SERRANO (2004) and it was found that the
prediction of bond line strength was highly depending on both the specimens’ type used and
adhesive properties, such as strength fracture energy, and the shape of stress slip behaviour of
the adhesive layer. But it was not found any information in the technical and scientific
literature about the gluing ability and adhesion strength of solid surface materials with other
materials.
Glue bond quality and durability can be affected in many ways, such as density, porosity
and smooth surface of the adherent (DUNKY et al., 2002) or non water absorption ability of the
solid surface material.
Therefore, it is very important enough knowledge about the gluing ability and adhesion
strength of solid surface materials with other wood based and non-wood materials with
different type of adhesives to be established.
2. METHODS AND MATERIALS
There is no standard which is intended to establish test methods for evaluating the gluing
ability or adhesion strength between wood based materials and composites like solid surface.
Due to the fact that the adhesives manufacturers are giving recommendations about the
strength characteristics of adhesives according to BDS EN 205 for the purpose of this study
this standard was used as test method. Another possibility is to be used BDS EN 13354:2008
(KYUCHUKOV, 2010)
2.1. Materials
Acrylic based solid surface material made in sheets with thickness (S2) of 6 mm was used
for this test and was purchased from Kolpa, Slovenia. Material has density of 1700 kg/m3,
MOE – 9700 N/mm2 and bending strength – 70 N/mm2.
Laminated (S1=18 mm) and non laminated particleboards (S1=16 mm), MDF (S1=6 mm)
and plywood (S1=17 mm) as a mass produced panels were used as wooden substructure
materials. Foam PVC boards (S1=19 mm) were used as non-wooden materials. They are light,
high-strength alternative to a wooden materials, which is designed to eliminate heavy and
hard to handle materials. PVC foam board is waterproof and do not distort in moisture or
water, so it is good choice to do furniture like bath cabinet and kitchen worktops.
2.2. Adhesives
Tree types of adhesives have been used for the purpose of this study – one component
polyurethane, rubber based and PVAc. A commercial product Sikaflex®-11FC+ was selected
as PUR adhesive. It is one part, moisture curing elastic joint and multipurpose adhesive based
on polyurethane, suitable for indoor and outdoor application. The joint width must be at least
10 mm but less than 35 mm. Hand pressure were used to set the element to be bonded in the
correct position.
Rubber based adhesive with commercial name Moment Express Fix PL 600 was used as
a second type. It is solvent base, styrene-butadiene copolymer, fast gluing and multipurpose
adhesive.
Folco Lit X 3000 PVAc based adhesive was taken as representative of the most
commonly used adhesives in the woodworking industry. It is an unfilled adhesive with cross
linkable groups with an application for surface bonding and assembly gluing as well gluing of
softwood and particleboards. Folco Lit X 300 PVAc adhesive has good water resistance with
a durability class D3 according to BDS EN 204 and good heat resistance: ≥ 7 N/mm2
according to DIN EN 14257 (WATT 91).
50
WOOD IS GOOD
2.3. Methods
2.3.1. Description of tests sample
Test samples have been prepared according to BDS EN 205 (Figure 1). The single-lap
joint, in which two sheets of different material were jointed together with an overlay of 10
mm have been produced. All five substructure materials were bonded with one component
polyurethane and rubber based adhesive. Plywood, non laminated particleboard and MDF
were bonded additionally with PVAc adhesive. All together 13 series of test samples have
been produced at 20 ºC room temperature. For each type of adhesive and substructure were
prepared 20 test samples. All the requirements given by the adhesive producers have been
met. Test samples have been conditioned for 7 days at 20 ºC and 65 % relative humidity.
Figure 1. Test sample for evaluating the tensile
shear strength of glued materials (units: mm)
Figure 2. Test sample for evaluating the tensile
shear strength of glued materials
2.3.2. Test method
All tests were carried out on universal testing machine. Tension load was applied to the
test specimens (Figure 2). The loading was continued until a non recoverable drop in load
occurred.
Ultimate loads were converted to tensile shear strength value by means of the expression
.
(1)
where
T – tensile shear strength, N/mm2
Fmax – ultimate force, N
A – gluing area, mm2
l – length of tested gluing surface, mm
b – width of tested gluing surfaces
Additionally the elastic deformation was recorded for each test sample.
51
WOOD IS GOOD
3. RESULTS AND ANALYSIS
The data from the research carried out to determine tensile shear strength of solid surface
materials with different wooden materials and foam PVC boards are processed statistically. In
the Table 1 and Figure 3 are shown the results of the test.
Table 1. Statistical data for tensile shear strength of solid surface material with: 1- Sikaflex®-11FC+
and plywood; 2 - Sikaflex®-11FC+ and MDF; 3 - Sikaflex®-11FC+ and laminated PB; 4 - Sikaflex®11FC+ and PB; 5 - Sikaflex®-11FC+ and foam PVC; 6 - Moment Express Fix and plywood; 7 Moment Express Fix and laminated PB; 8 - Moment Express Fix and foam PVC
1
2
Type of adhesive and material
3
4
5
6
7
8
Mean value
Number of
test samples
Standard
deviation
Coefficient of
variation
Max
N/mm2
0.99
1.36
1.19
1.23
0.24
4.95
1.96
1.67
no
16
16
15
15
12
15
17
15
N/mm2
0.20
0.18
0.21
0.23
0.05
1.03
0.38
0.30
%
19.9
13.4
17.2
18.3
20.3
20.9
19.2
18.0
N/mm2
1.30
1.60
1.60
1.50
0.31
6.60
2.80
2.10
Min
N/mm2
0.70
1.00
0.90
0.90
0.19
3.90
1.20
1.00
2
1.00
1.30
1.10
1.30
0.22
4.50
1.90
1.70
Median
N/mm
Results for tensile shear strength for samples bonded with PVAc adhesive are not given
in the data. The reason is that the test method according BDS EN 205 has some
disadvantages, especially when good adhesion of the glue is performed. For these test groups
shear strength was equal or exceeded shear strength of the wood based or solid surface
materials and no significant differences between different bonding conditions can be proofed.
Test samples with substructure of MDF and particleboards bonded with rubber based
adhesive are also not included because the wood based materials had less strength compared
to the bonding line. For both combinations discussed above another type of testing should be
used.
One component polyurethane adhesive with a commercial name Sikaflex®-11FC+ shows
relatively good bonding strength (tensile shear strength from 0.99 to 1.36 N/mm2), close to
the recommended from the manufacturer value of 1.5 N/mm2. The only one exception is for
the test samples with foam PVC boars, where the strength is 0.24 N/mm2. For this
substructure either a different adhesive or a primer before gluing must be used. The highest
strength was observed for test samples made of solid surface and MDF. Based on a t-test the
differences between test samples 2 and 4, and 3 and 4 are not significant. With all the other
results the differences are statistically significant (p=0.05). The observed way of destroying of
the bonding line at this group of test samples showed that less adhesion is achieved with the
solid surface material. As it is non porous substance, for better results the surface should be
processed with fine abrasive pad. An exception is only the group of foam PVC where the
adhesion with solid surface material is higher compared to the PVC.
Rubber based adhesive with a commercial name Moment Express Fix PL 600 gives in
generally highest bonding strength compared to the one component adhesive. For the
plywood substructure the difference is five times. The same situation is with Foam PVC
where the bonding strength is 1.67 N/mm2. For MDF and particleboards bonding strength was
higher than the strength of the wood based materials which were destroyed. The highest
measured tensile shear strength nearly 5 N/mm2 was observed for the test samples of solid
52
WOOD IS GOOD
surface and plywood. This corresponds to the recommended from the manufacturer value of 5
N/mm2. This result may be due to a fact that the adherent is solid wood as veneer. All
differences are statistically significant (p=0.05).
7,00
Tensile shear strength, N/mm2
6,00
5,00
4,00
3,00
2,00
1,00
0,00
1
2
3
4
5
6
7
8
Figure 3. Tensile shear strength of solid surface materials with different wooden and non-wooden
materials: 1- Sikaflex®-11FC+ and plywood; 2 - Sikaflex®-11FC+ and MDF; 3 - Sikaflex®-11FC+
and laminated PB; 4 - Sikaflex®-11FC+ and PB; 5 - Sikaflex®-11FC+ and foam PVC; 6 - Moment
Express Fix and plywood; 7 - Moment Express Fix and laminated PB; 8 - Moment Express Fix and
foam PVC
Elasticity of the bond line is an important characteristic for the gluing ability of different
adhesives to solid surface materials with wood based and non-wood based materials. It is
clear visible from the Figure 4 and 5 that one component polyurethane adhesive with
commercial name Sikaflex®-11FC+ has higher bond line elasticity. Opposite, the stronger
bond line, obtained with rubber based adhesive has lower elasticity. No data has been
recorded for PVAc adhesive because for this test groups shear strength were equal or
exceeded shear strength of the wood based or solid surface materials.
Sikaflex®-11 FC+ plywood
Sikaflex®-11 FC+ MDF
Force F, N
450
400
350
300
250
200
150
100
50
0
-0,5
0,5
1,5
Deformation ɛ, mm
2,5
Figure 4. Deformation of the bond line of test samples bonded with one component polyurethane
adhesive Sikaflex®11FC+
53
WOOD IS GOOD
MEF PL 600 - plywood
450
MEF PL 600 - LPB
400
MEF PL 600 - FPVC
Force F, N
350
300
250
200
150
100
50
0
0
0,5
1
1,5
Deformation ɛ, mm
2
2,5
Figure 5. Deformation of the bond line of test samples bonded with one component rubber based
adhesive Moment Express Fix PL 600
This study shows that the investigation on the gluing ability and adhesion strength of
solid surface materials and wood based and non-wood based material with different adhesives
put a lot of questions which has to be aim of a further researches in this field.
4. CONCLUSIONS
1. The test results indicated that, in general, all the tested adhesives – one component
polyurethane (Sikaflex® 11 FC+), rubber based (Moment Fix Express) and PVAc (Folco
Lit X 3000) are suitable for gluing solid surface materials to wooden materials as
decorative elements.
2. For establishing a high strength bond for a structural joint has to be used a combination of
plywood and solid surface materials bonded with one component polyurethane (Moment
Fix Express) or PVAc adhesives.
3. For better adhesion strength is recommended solid surface material to be bonded with
rubber based adhesive to the substructure material made of foam PVC board.
4. One component polyurethane adhesive with a commercial name Sikaflex® 11 FC+ has
better elasticity of the bonding line compare to the rubber based tested adhesive.
5. For evaluating the adhesion strength of solid surface materials with wood based materials
with PVAc adhesive a test method different to BDS EN 205 should be used.
6. For determination of adhesion strength of solid surface materials with other wood based
and non-wood materials BDS EN 205 test method is suitable for adhesives with bonding
strength less than 6 N/mm2.
5. REFERENCES
ADAMS, R.D.; COMYN, J.; WAKE, W.C. (1997): Structural adhesive joints in engineering. Chapman &
Hall.
DUNKY, M. (2003): Adhesives in the wood industry. Handbook of Adhesive Technology, 2.
54
WOOD IS GOOD
KONNERTH, J.; GINDL, W.; HARM, M.; MÜLLER, U. (2006): Comparing dry bond strength of spruce
and beech wood glued with different adhesives by means of scarf-and lap joint testing
method. Holz als Roh-und Werkstoff, 64 (4): pp. 269-271.
KYUCHUKOV, G. (2010): Test method of the adhesive strength of solid wood panels. DMT – Design,
Materials, Technology, XII, 66, (3): pp. 62-66.
KYUCHUKOV, G.,; KYUCHUKOV, B.; JIVKOV, V.; MARINOVA, A. (2001): Influence of wood species,
type of adhesive and the method of testing on the adhesive strength. Proceeding of the XVth
International Symposium “Adhesives in Woodworking industry”. Slovakia, Zvolen, 97-100
DUNKY, M., A. PIZZI, M.VAN LEEMPUT: (2002): State of the Art-Report. COST- Action E13, part 1
(working group I, Adhesives), European Commission, Brussels, Belgium.
SERRANO, E. (2004): A numerical study of the shear-strength-predicting capabilities of test specimens
for wood–adhesive bonds. International journal of adhesion and adhesives, 24 (1): pp. 23-35.
EN 205:2006 Adhesives – Test methods for wood adhesives for non-structural applications Determination of tensile shear strength of lap joints.
DU PONT
URL:http://www.dupont.co.uk/products-and-services/construction-materials/surface-designmaterials/brands/corian-solid-surfaces.html
55
WOOD IS GOOD
Lathe Tool - It’s Development from the Ancient times to Nowadays
KAMPERIDOU Vasilikia*– BARBOUTIS Ioannisa
a
Aristotle University of Thessaloniki, Faculty of Forestry and Natural Environment, Laboratory of Wood
Products and Furniture Technology, Thessaloniki, Greece
*
Abstract - One of the most important wood processing machines from ancient times till our times is
the lathe. The tool of lathe occupies a prime position in the group of wood cutting machine tools and is
a valuable invention for human mankind, since it offered the possibility of constructing a huge variety
of objects and surfaces. The specific work indulges in the history of the lathe, the progress and
evolution of this tool from the past time to the present. Additionally, the construction and operation of
the lathe is analysed, presenting also some general information on lathes, the key components, types of
lathes, the main turning types, the cutting tools and the tool holder’s axis of the lathe and how some of
them changed through the years.
CNC / lathe / revolver lathe / tool / turning / wood processing
1. INTRODUCTION
Over the centuries, mankind has recorded very significant progress, part of which was the
development of a range of tools and machines that contribute to the use of different materials,
such as wood, metal, etc. satisfying in that way several human needs. For the treatment of
materials and the production of various products, various tools were devised and implemented
in machines, using energy to achieve the work with much less effort and time.
Such tools are mainly used in the treatment of materials (wood, metal, etc.) in such a way
as to obtain the desired configuration of shapes, forms and dimensions, by means of material
removal. Apart from the conventional tools that work manually, now there are also automatic
tools (CNC, NC, etc.) connected to a computer, which are characterized by accuracy and
clearly greater efficiency. There are several tools which work by removing material, such as
“cutting” machine tools, that basically cut the raw material into smaller pieces or cut shaped
pieces of the material, in order to avoid creating much waste during the process, while the
material is being transformed into an accomplished in form and dimensions product. Also, in
recent years, there is a confluence of several separate machines that work on a production line
or a flexible machining system.
The lathe occupies an important position in the group of cutting tools and a valuable
invention for humans, since it offers the possibility of constructing a huge variety of objects
and surfaces. The specific work indulges in the history of the lathe, the progress and evolution
of this tool from the past time to the present. Additionally, the construction and operation of
the lathe is analysed, presenting also some general information on lathes, the key components,
types of lathes, the main turning types, the cutting tools of the lathe and how some of them
have changed through the years.
2. HISTORY OF LATHE
Lathe is one of the first tools used and very useful to mankind, even nowadays that the
technology has been recorded a great progress (STEEDS, 1964). The lathe took its name by the
prefix «τορ-» («tor»), which comes from the verb «τείρω» («tiro»), which means rub (or
chagrin intensively) and the suffix «-νος» («nos»), and basically, it is a tool built with the
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intention of formulating a material through the clamping and rotation of the force under
appropriate cutting means.
The operation of the lathe is based on a very simple and understandable principle. Wood
is forced to rotate on an axis, while a sharp tool cuts, scrapes or smoother it, in order to give
the final shape to the product. The wooden element is fastened at two points, which form the
axis of rotation (STEEDS, 1964). This simple machine, the machine of lathe, is used for
thousands of years and some of the reasons are listed below. Essentially, with pretty much
ease, lathe produces objects of round surface, it is a machine of inestimable value and
contribution to the construction of wheels for carriages, windmills or pumps. With the help of
the lathe, rotating spindles are easily assembled in structures of high complexity, such as
chairs, tables, beds and other furniture. From an aesthetic standpoint, the lathe helps in
creating aesthetic, decorative objects and surfaces, which would be impossible to be
constructed without the use of lathe. Combining simplicity in engineering, adaptability, and
high aesthetics, turning has been proven to be a valuable practice adopted and strongly
requested by the market, while it is part of the European culture (RETTIE, 2009).
The invention of the lathe is placed in the ancient times. More specifically, it was initially
known to the Egyptians, and some years later on the Syrians, Greeks, Romans and later
throughout all the Byzantine Empire. One of the earliest depictions of lathe was the fresco
found in Ptolemaic dynasty tomb. In those years, the lathe was also known by other names,
derived from the turbulence and rotation or the material removal, while later people began to
use the word "tearing" as the name of the lathe. Several sources indicate that the tool of lathe
was used since 1300 BC by the Egyptians. Also in the work of Herodotus the use of the lathe
in pottery is reported, demonstrating the fact that they had already known and used the lathe,
but as evidenced by scholars such as for example, by Varoufakis, who studied the crater of
Derveni, the lathe of metal objects seems to be used already those years. The type of “arched”
lathe depicted in the images that follow, was a revolutionary discovery of those ancient times,
since for the first time only one craftsman was enabled to handle the lathe, while the earlier
lathes required definitely two craftsmen. These earliest forms of lathe were the vestibule of
the evolution of the lathe, and the mechanical evolution in general (NOESIS, 2012).
A.
B.
Figure 1. A., B. Arched lathe (http://www.archimedesclock.gr/gr/kataskeves/diafora/tornos.html)
The lathe was also used by craftsmen who made pulleys, gaskets, carriages, connectors,
copper utensils, anvils, bells, etc. From 4th to 7th century, there is evidence that show the lathe
in England, while in 1180 according to data the first turner guild was established in Cologne
(Germany) (RETTIE, 2009). In the Middle Ages, European turners seem to prefer a kind of
lathe called "Spring" lathe. In this form of lathe, there is a frame of sufficient height in order
the turner to stand comfortably in it, which holds tightly the fixed element and rotates it
between two points of an axis, fixed on two sharp metal parts that otherwise are also called
centres. There is a string that runs all the way from the tip of the pole, to the base, so as to
take easily place the phenomenon of recoil, necessary for the rotation of the wooden piece.
The string is well fastened around the piece that is going to be turned, at the point where
exactly it is needed to be turned, in order the piece to be drifted by the string as it moves,
while the string ends in this kind of a pedal (or pedals) located at the lowest point the lathe. At
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this point where the operator applies his leg, he causes the movement, while as the operator
leaves the pedal, the movement is released. Simultaneously, the operator apply to the surface
of the wooden element, knives and other cutting tools, in order to give the appropriate shape
and dimensions to the material (http://www.historicgames.com/lathes/springpole.html).
The string lathe has been proven to be of particularly high adaptability. It is lightweight
and portable, two very important factors for manufacturers of that time, who may be moved
and travelled to places where raw materials were in abundance. That lathe was also easy to be
manufactured, and most of the necessary for its construction parts, were easy enough to be
fixed by the manufacturer himself. The main drawback mainly derived from the design of this
lathe was its relatively low speed, and the limitations in size and weight of the wooden object
that was going to be turned. Until the mid 19th century, despite these limitations, the lathe that
uses string remained the most popular among other types of lathe, and was preferred mainly
by chair and various artefacts manufacturers (RETTIE, 2009).
a)
b)
c)
Figure 2. a) foot spring lathe, b)hydrokinetic turning (1425-1523), c) lathe with band (UOC)
Many variations of this lathe design followed, incorporating also a lever (handle), in
order to replace the specific frame that was situated above the head of the operator, with a
frame on the basis of the tool or with a bow that holds the string and converts the whole
process, to produce a constant rotational movement, providing greater convenience to the
operator (RETTIE, 2009).
In the late 15th and early 16th century, the point of cutting tools deposition as the turning
object was rotating appeared for the first time in lathes of that time. This added surface was
based on pins, as is shown in figure 3, and the surface is fixed in the desired angle using some
wedges, in a way that the cutting tools can rely on a stable surface to achieve greater accuracy
during turning and secondly, to increase the possibilities of turning and range of turned
surfaces that could be achieved.
The most popular lathe used in the Middle Ages was the “spring” lathe. One of the main
achievements in the operation of the lathe was the passage of the back and forth motion in
continuous rotational movement, which ensure faster rotation, while giving the possibility of
processing parts of much larger dimensions. In addition, the design and construction of this
lathe, reduced the effort and energy consumed by the turner. As evidenced, from the Middle
Ages, it was known how to converse the reverse movement into a rotational movement. With
the help of some mills that were taking advantage of the running water movement, the motion
was transferred using some arms, to reciprocating saws, giving a continuous rotary motion.
Over the years, the mechanical skills of craftsmen were further developed and the complexity
of the mechanisms as well, which was often increasing the cost of these structures and
machines. To sum up, initially, the first lathes that appeared were moving with the power of
man muscles (foot turning), and then with the help of water movement (hydrokinetic turning),
referring to downstream mills and finally the motorized turning lathes (UOC, 2012).
Some lathe designs have been found also in sketches of Leonardo da Vinci, who besides
having captured, is likely to have also improved some of these lathe designs that have already
existed. The existence of continuous rotational motion lathes was set in from 1560 to 1570
and was often depicted in books ("Book of Trades" by JOST AMMAN, etc.).
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B.
C.
Figure 3. a) Lathe continuous rotary motion bearing burin (Archive of Samian Folklore, 2008), b), c)
Furniture and objects which required turning for their construction
The use of these lathes of the continuous rotation was quite limited in those years, mainly
due to higher costs, the abundance of older lathes of reverse motion, and probably, due to the
restrictions that were being raised by the trade unions of that era. More specifically, the urban
trade unions set often restrictions on the use of specific tools or methods used by themselves
as craftsmen. For the lathe, in particular, there have been many conflicts over who has the
right to use it, while the regime that tried to establish a situation where one had to have a
special permission in order to be able to use the lathe was not preceded. In the countryside,
the restrictions were not so intense and craftsmen could trade lathes and use their own tools.
There were many furniture pieces and small objects that required turning during their
construction, as well as various connections of wooden or metal components such as the most
frequently used type of connection "Mortise and Tenon" (Figures 3 b and c).
The lathe operator undertook mainly indoor furniture, and one of the most popular
furniture manufactured with lathe was the tripod stool (Figure 3 b), which is a highly stable
cabinet formed after connecting wooden pieces of cylindrical section. It used to adorn the
homes of both villagers and wealthy families (nobles, clergy, scholars, etc.) and many images
of this furniture have been recorded dating from the early 16th century onwards. Various
elaborate versions of this turned furniture followed, while the following years back and also
slots for elbows were added to the furniture, giving an integrated chair (17th century). Except
furniture, plenty of other objects were being manufactured using lathe, such as wind, mortar,
mugs, cups, plates, tool handles, castors, trolley wheels, boxes, sieves, various games, pulleys,
buttons, cuffs, scales, pumps etc.
The artisans of lathe in the Middle Ages were using a variety of wood species, and based
on found Anglo-Saxon and Scandinavian artefacts (ca. 990-1000 AD), it has been proved that
maple, birch, walnut and ash were the wood species chosen more often, while yew, pixos,
beech, and the black pine were used under certain conditions. As it is known, each wood
species has different physical and mechanical properties, and therefore, its behaviour during
machining can greatly vary. Generally, denser wood achieves better results, better turning and
smoother surfaces. The oak, for instance, although was routinely used in furniture wooden
joints construction, as it was demonstrated after some years, it is not easily machined, due to
the structure and layout of the annual rings, therefore it was abandoned.
In Middle Ages, the turners worked mainly with non-conditioned wood, of high
humidity. The cause of using wet wood during turning is that the humidity makes the wood
softer, which is more easily cut and thus, the operation of lathe is better. As the wood fibres
are soft and flexible, the technician applies the gouge in rotating piece, removing material as a
continuous wooden strip. Of course, the wet timber is not suitable, when the machining
should be done internally, which means on the inner side of the object, a cavity, for example
in glasses, cups etc. The reason is that when the timber starts to dry, different dimensional
changes in the transverse, radial and tangential direction of wood will be caused, which will
lead to deformation or breakage of the structure. The timber can be machined wet, but during
the connection of the pieces and the construction of the wood product is necessary wood to be
dry (10-12 % moisture) (RETTIE, 2009). As LEON BATTISTA ALBERTI also reports, during the
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15th century, turners used to immerse the timber in water before the use and often leave
covered with mud for 30 days in order to facilitate its handling, contributing to a more stable
material and avoiding checks and distortions of wood (RETTIE, 2009).
It is striking that some researchers report that the history of modern mechanics starts in
the last years of the 18th century, when Henry Maudslay, of English origin, produces the first
lathe which created thread, generating the known screw. Clearly, if one compares the 18th
century lathe, to today's lathes, he would undoubtedly conclude that the lathes of that era were
very time consuming, laborious and of low accuracy, but it was of great significance that that
tool was developed in the lathe that we know today (BURGHARDT et al., 1959).
3. THE BASIC COMPONENTS OF LATHE TOOL
The lathe is a machine tool used in the construction of objects of circular cross section, as
mentioned above. The main movements during turning up of the main motion are the rotary
motion of the object and the feed motion of the cutting tool which is rectilinear (BURGHARDT
et al. 1959). Some of the most important pieces of a common machinist lathe are the lathe bed
(on the lathe), the electric motor, headstock and propulsion, or turning area with
predetermined dimensions (diameter, turning length), the tool axis or the centre line/ tailstock,
the drive threading axis, feed or propulsion axis and sleeve axis (PARIKOU, 1988). The tool of
lathe can yield rotational, curved, concave or flat surfaces.
a)
b)
Figure 4. a) The basic parts of a lathe: a. lathe bed, b. headstock, c. tool axis, d. tailstock, e. feed
gear box, f. drive threading axis or lead screw, g. feed or propulsion axis, h. switch bar, b) Turning
and the motions carried out (UOC)
One of the most basic parts of the lathe is the lathe bed, which is based on two pedestals
together via a very strong beam. The lathe bed features in the upper flat slides or prisms,
which should be in perfect alignment and highly resistant to corrosion. During the turning, as
mentioned previously, a rotational movement is performed around the axis of the wood, while
the tool is displaced continuously linearly parallel to the axis of the piece until the desired
shape of wood is achieved. This longitudinal turning can be internal or external of the
material. Apart from this longitudinal turning, it is possible to have a frontal, collateral,
lateral, conical, spherical, curved turning and the corresponding surfaces, and also threading,
grooving, cutting of shoulder nerve etc. (PARIKOU, 1988).
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a)
b)
e)
h)
c)
f)
d)
g)
i)
j)
Figure 5. Types of turning treatments: a) external longitudinal, b) internal longitudinal, c)
external transversal, d) internal transversal, e) external taper/conical, f) internal taper/conical, g)
external profile, h) internal profile, i) external thread, j) internal thread (UOC)
A lathe of general uses can implement the following basic turning types: Turning external
and internal cylindrical surfaces, turning of flat surfaces / transverse turning, turning of
conical surfaces, boring small or deep holes, eccentric turning (cams, crank shafts), turning of
specific shape / profile, cutting internal or external threads of all forms, treatment of external
and internal spherical surfaces, making winding of springs knurling etc., sanding onto lathe
bed, grooving and cutting.
At the left edge of the bed, there is the gearbox, with the necessary number of gear means
/ clutches, necessary for the transmission of the rotational speed to the spindle motor. The
alongside and transversely promotional moves are achieved through the tool axis, which
comprises the longitudinal, the transverse slide and the slide of the rotating plate. All the
cutting tools are fixed in a tool holder, which is located in front of the bed (tool carrier box)
and run along slides. The movement of tool axis is accomplished either manually with the
help of the lever, through a rotation which press the gear wheel engaging with a toothed rack
fixed to the bed or automatically through the rotating axis, the propulsion axis, while for
threads cutting, respectively it is accomplished through a threading axis (PARIKOU, 1988).
4. CONSTRUCTION AND FUNCTION OF LATHE
While the pieces of circular cross section rotate around their axis in lathe machine,
various types of cutting tools are applied on the surface, forming the desired design.
Undoubtedly, the range of patterns that may be achieved is very wide (BURGHARDT et al.
1959). The cutting tools may be held by the operator and the machine to be driven in an
appropriate manner by him or they may be applied to the moving element tool axis carrying
the selected tool and then the operator just drive the entire system. Of great importance is the
stabilization of the piece that is going to be turned, in order to avoid accidents and destruction
of wood.
There are lathes of various sizes depending on the dimensions of the treated material. It is
very important the placement of the lathe at a suitable height, and the stabilization of a solid
substrate, in order the turning process to be convenient and safe for the operator (ERNEST,
1980). A lathe of acceptable quality usually has an engine of ¾ or 1 horsepower capacity.
Most lathes are capable of switching 3 or 4 different speeds. Higher accuracy and purity are
usually achieved at higher speeds. Initially, when the material is still completely raw the
speed is kept rather low, while the material is shaped as the speed rises. Additionally, the
heavier and denser wood we have, the lower speed should be applied (ERNEST, 1980).
The cutting motion that is carried out by the rotation of the object is called cutting speed
(Vc) (MANTEMIS, 1996). There are lathe beds that give approximate values of cutting speed
for each material and diameter of the object. Upon the engine of lathe one can usually find a
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fixed chart to read the speed n with which the lathe operates, while there is also the possibility
of calculating the speed through beds, putting the cutting speed and wood element diameter
one can find the respective speed of the lathe (MANTEMIS, 1996).
The cutting speed or as it is called otherwise, the speed of rotation of the turned wooden
piece and the speed of propulsion which is also called movement of the tool in a direction
parallel with the axis of wood, depend mainly on the nature of the treated material, the
material that the tool is made of, and the desired quality of wood surface one wants to achieve
(MANTEMIS, 1996). In planning treatment, usually a large propulsion and cut depth is adopted,
while in treatments where great attention is crucial for the final result, such as the finishing
treatment, usually small cutting depth and propulsion is selected. Referring to propulsion,
essentially one means to the movement that the tool completes (in millimetres) in one rotation
and is selected according to the engine power and the desired final surface quality.
Cleaning the lathe is a very important and necessary process and should be take place
when the lathe is idle. A small piece of cloth soaked in kerosene, can be used to remove dirt
and oils, while the surfaces should be passed with a dry cloth in order to remove residual of
kerosene. The quiet running bearings should be lubricated each time before use, with the
necessary quantity of oil and checking of pipes that lead the oil in different parts of the
machine should be frequent, in order to avoid their blocking (BURGHARDT et al., 1959).
The number of shapes and kinds of cutting devices used in lathe is quite large, despite the
efforts that have been made in the direction of standardization of these cutting tools and thus
reduction in their number (STEEDS, 1964). Very important is the form of the waste coming
from the cutting tool and tool material and its resistance to wear and tear. The hardness of the
tool should be maintained even at high temperatures, in order to prevent the occurrence of
cracks (MANTEMIS, 1996). The tools are typically made of steel (either pure steel, or alloys), a
very durable material which is sufficiently elastic and resistant at high temperatures (400600 oC). Tools are usually coated with titanium nitride to withstand even more to wear.
5. LATHE TYPES
The tool of lathe, following the general technological development has been evolved and
has met all the requirements of structures characterized by accuracy, productivity and
automation. Those three factors are essential in each tool for high volume production, good
quality product and low cost. In terms of use, the lathes are divided into lathes of general use
and lathes of special purposes.
In the lathe of general use, almost all turning processes can take place. There is the
potential to receive wooden items between the centres and for this reason, this lathe is also
called "lathe of the centres". These lathes are usually equipped with mechanical motion for
propulsion and therefore, are often called "propulsion spindle lathe" (MANTEMIS, 1996).
In this category of lathes is also included the “centre-line parallel” lathes, or “universal”,
(equipped with propulsion axis and screw threads), the “centre-line parallel productive” lathes
(equipped only with a propulsion axis or a hydraulic transmission of propulsion), “parallel”
with a variety of knives, “rotational” or “revolver” lathes, the “copying” lathe, the “semiautomatic” and “automatic”, “vertical” and “frontal” lathe.
The “revolver” lathe, referring to the facilities it offers, lies between the “universal” lathe,
that all operations are driven by the craftsman and the completely “automatic” lathe. The
automatic lathe operates either with a purely mechanical program of automation, or by an
electronic control unit (NC or CNC). The “revolver” lathe is characterized as "semi-automatic
machine", used mainly where there is a relatively large production. In this way, in a wide
variety of products, the “revolver” lathe performs the same work in much shorter time,
compared to the conventional lathe, while the accuracy achieved is quite the same.
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Called also as "expertised" or "sectoral”, lathes of special purposes are used in specific
processing and turning of objects in various industries. For example, lathes for cutting
threads, lathes of the automotive industry, lathes machining crankshafts, lathes in the railway
etc. The classification of lathes in this category depends on the use, the characteristic
structural dimensions and different sizes.
6. CONCLUSIONS
Taking all the above into account, turning can provide various forms of the work piece
through the combination of various movements, and use of appropriate cutting tools. Apart
from conventional lathes, which are guided by the operator who makes all the necessary
movements and arrangements for the treatment, lathes can also be driven digitally and in this
way the movements and settings require much less human involvement since the electronic
guidance unit and the developer undertake all the main work. In conclusion, it could be
mentioned that the lathe is one of the emerging tools used during the evolution of humanity,
has been a valuable tool over the years, enabling the production of a huge variety of surfaces
and objects of high quality, usability and aesthetics. Through the years, several features of
lathe machine have been changed and improved, providing greater precision in dimensions
and shape of the wooden elements, higher machine efficiency, higher production speeds, ease
of machining, and less effort and risk of accidents for the operator of lathe.
7. REFERENCES
BURGHARDT, H.; AXELROD, A.; ANDERSON, J. (1959): Machine Tool Operation – Part 1: Safety,
Measuring Tools, Bench work, Drill Press, Lathe, Forge work. McGRAW – HILL BOOK
COMPANY, ISBN 07-008961-2.
ERNEST, S. (1980): The Mitchell Beazley encyclopaedia of Working in wood. Mitchell Beazley
Publishers Limited. ISBN 0855332905.
MANTEMIS, S. (1996): Tool machines I. Library mechanical engineering. European technological
Publishing - G. & S. Parikou & Co., ISBN 960-331-132-4.
ΝOESIS (2012): Ancient Greek Technology. Thessaloniki Science Center & Technology Museum.
URL: http://www.tmth.edu.gr/aet/thematic_areas/p527.html.
PARIKOU, G.Ι. (1988): Machining Technology. Publishing ΙΩΝ. ISBN 960-405-076-1.
POLLACK, H.W. (1976): Tool design. Reston Publishing Company, Inc. ISBN 0-87909-840-6.
PREFECTURE OF SAMOS (2008): Photo Archive of Samian Folklore,
URL: http://culture.samos.gr/c/portal_public/
RETTIE, I. (2009): Lathes Part 1: About Medieval and Renaissance Lathes.
URL:http://www.bloodandsawdust.com/Blood_and_Sawdust/Lathes_Part_1__About_Medieval_
and_Renaissance_Lathes.html.
STEEDS, W. (1964): Engineering Materials Machine Tools and Processes. Longman Group LTD,
London, ISBN 0582427290.
UOC, TECHNICAL UNIVERSITY OF CRETE (2012): Class textbook. Polytechnic Faculty of Crete,
Laboratory of Micromechanics and Structures.
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Design and Manufacturing of Organic Shape Furniture
KITEK KUZMAN Manjaa – ŠERNEK Milana – KARIŽ Mirkoa*
a
Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana,
Slovenia
*
Abstract – Wooden furniture of organic shapes was mostly handmade in the past, each piece was
almost unique, since the manufacturing processes did not allow repeatability and larger quantity
production of the same products. Today, modern 3D modelling software leads to completely different
prospective in wooden furniture design and production. It enables modelling of any kind of shape,
based on ideas, natural shapes, even 3D scanned existing shapes, etc. Furthermore, prototypes can be
3D printed. This enables that visual presentation of designed form is made in real. Based on the
printed forms virtual models can be improved leading to the final sophisticated model. Additionally,
during design process the best construction details can be made to improve material efficiency and
manufacturing time. Final product can be than made on CNC machines, enabling reproduction of the
same product of desired shape in chosen quantities.
furniture design / 3D modelling / tectonic of timber architecture
1. INTRODUCTION
1.1. Organic design
Organic architecture is a philosophy of architecture which promotes harmony between
human habitation and the natural world through design approaches so sympathetic and well
integrated with its site, that buildings, furnishings, and surroundings become part of a unified,
interrelated composition. Organic architecture is a term Frank Lloyd Wright used to describe
his approach to architectural design. The philosophy grew from the ideas of Frank Lloyd
Wright's mentor, Louis Sullivan, who believed that "form follows function." Wright argued
that "form and function are one." PEARSON (2001) describes organic design as design inspired
by nature and sustainability, health, conserving, and diverse, unfold, like an organism, from
the seed within. It follows the flows and is flexible and adaptable. It also satisfies social,
physical, and spiritual needs, grows out of the site" and is unique. It celebrates the spirit of
youth, play and surprise and expresses the rhythm of music and the power of dance. The art of
deploying construction technology in such a way that it forms an integral component of the
design and actively helps to shape it is what KENNETH FRAMPTON (1995) defines as tectonics.
With the inspiration coming from the wood itself is the aim to offer a wide selection of
live edge wood furniture boasting organic shapes and natural flaws that add to the innate
beauty and sensory experience. The easy machinability of wood makes it an ideal material for
digitally controlled processing. For this reason, the timber industry is well equipped with such
machinery, and timber is taking on the status of a high-tech material (BURI – WEINAND, 2011,
2012) (Figure 1).
Figure 1. The tectonics of timber architecture in the digital age (folding, bending, weaving)
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1.2. The tectonics of digitally designed timber furniture: the organic forms in wood
It is possible to show how parametric design tools can be created that are specifically
tailored to timber and its material properties. Tectonics – the interplay of architectural
expression, efficiency and the construction of support timber structures – is one of the focuses
of our research and teaching at the Department of Wood Science and Technology at the
University of Ljubljana.
New wood based materials (liquefied wood, modified wood, densified wood) and
processing technologies along with the new possibilities for depicting and calculating support
structures play an important role here. The aim is an efficient interlinking of design and
construction that integrates the architectural, support-structure-related and production
requirements, leading to sustainable and high-quality solutions (Figure 2).
Figure 2. The tectonics of timber architecture as reflected in its production conditions
1.3. Furniture and production conditions
The life cycles of products are becoming increasingly shorter, leading to an increasing
need for intensified development of new products or updating the existing ones. Computeraided manufacturing (CAM), in which computer-aided design (CAD) and computer
numerically controlled (CNC) machining are integrated for the production of parts, became a
viable option for the woodworking industry in the 1980s (WIEDENBECK – PARSONS, 2010) and
is one of the possibilities for reducing design and development time for new products. In
modern furniture industry, CNC working centres are widely used, especially when high
quality of product and flexibility of manufacturing process are expected (GAWRONSKI, 2012).
The new technologies have had great effect on the professions devoted to threedimensional design work. Processes like modelling, performing basic stress and deformation
analysis, and even the production of rapid prototypes can be currently done by a single
designer without any need for a range of specialist. Therefore, an experienced designer can be
more effectively involved in any design decision. Virtual simulation of product enables
designing of optimal design solutions (MIJOVIĆ et al., 2006).
2. CASE STUDY
The information dictating the form of a work piece, which the human previously
provided through a one-time machine setting, is now directly integrated into the machine. The
information flow from the control program is variable, meaning that components of various
shapes can be manufactured without any time losses in production.
The idea of the case study was to design wooden sitting element / chair based on existing
organic shape. The basic form for design was simple river stone (Figure 3). The aim of this
study was to use available modern 3D modelling software to model the furniture (prototype)
and make it with CNC router.
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Figure 3. Simple river stone
First the photo of river stone was taken from each side (top, front and left view). The
photos were then imported into SolidWorks software, which was used to model our stone.
SolidWorks 3D CAD solutions enable quick transformation of new ideas into great products.
SolidWorks solutions cover all aspects of product development process with a seamless,
integrated workflow-design, verification, sustainable design, communication and data
management. Designers and engineers can span multiple disciplines with ease, shortening the
design cycle, increasing productivity and delivering innovative products to market faster.
Silhouette of the stone was drawn based on these photos (Figure 4).
Figure 4. Silhouette of the stone (modelling with SolidWorks)
The model of the stone was then made with Surface loft. This was initial, base form,
which was the starting point for further design of furniture. Several models were then made
with different seating surfaces and dimensions. Bottom part of stone was flattened to ensure
stability of stone. Also upper part of stone - a seat was ergonomically designed to fit the
contours of the body (Figure 5).
Figure 5. Different model designs
For better visualisation of selected models 3D printing technique was used to make rapid
prototypes. "Experience rapid prototyping" enables design team members, users and clients to
gain first-hand appreciation of existing or future conditions through active engagement with
prototypes. We illustrate the value of such prototypes in four critical design activities:
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understanding existing experiences, exploring design ideas, in communicating design
concepts and to improve the information required to successfully market a new design.
3D printer ZPrinter 450 was used to make models of selected shapes (Figure 6).
Figure 6. 3D printed prototype M 1:5
For final production the most efficient process was tried to find. It was decided that CNC
router will be used to carve the surface of the furniture.
Choice between several options was made - to make it from larger block of wood- half of the
stone, or to slice the model to several slices and curve each slice individually and then
assemble these slices into final product (Figure 7).
Figure 7. Sliced model
It was determined to make model from larger blocks of wood - half of stone, because that
was easier for machine operator- only two longer CNC programs had to be made (one for
each half) instead of several short programs for each thin slice of product. The main cost for
production of the stone was CNC machining so reduction of time for CNC machining was
tried.
Also optimisation of material efficiency was needed, and first idea was to made solid
block of wood by bonding lamellas. This could be easier to do, but a lot of material would be
wasted and also the product would be much heavier. So it was decided to make frame of
wood, which than was bonded into block, so that the block was hollow (Figure 8). This
reduced the material consumption and also made the product lighter. So the volume of used
wood was only 0.12 m3.
Figure 8. Frames of wood bonded into block
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WOOD IS GOOD
Selected finished 3d model was than exported from SolidWorks to AlphaCAM software,
which was used to make a program for CNC router. 5-axis CNC machining centre was used
to carve product.
Figure 9. 5-axis CNC machining centre and products
3. CONCLUSIONS
An efficient interlinking of design and construction that integrates the architectural,
support-structure-related and production requirements, is leading to sustainable and highquality solutions. New organic design is a manifesto for wooden furniture of organic shapes
in a way that is both aesthetically pleasing and kinder to the environment. It illuminates key
themes of organic architects, their sources of inspiration, the roots and concepts behind the
style, and the environmental challenges to be met.
Today there is a response to a new age of information and ecology; architects and
designers are seeking to change the relationship between products and the natural
environment. Students can also experience prototyping's impact on design, working exactly
like professional designers and engineers. This project gave them the rigorous ground-level
education they need to develop strong backgrounds in science and engineering. They
extended existing 3D modelling knowledge with technologies like 3D printing and CNC
routing.
Acknowledgements: The authors wish to thank the Slovenian Research Agency (ARRS) in
the frame of research programme P4-0015-0481.
4. REFERENCES
BURI, H.U.; WEINAND, Y. (2011): The Tectonics of Timber Architecture in the Digital Age. In:
Building with Timber Paths into the Future, Munich, Germany: Prestel Verlag, pp. 56-63.
BURI, H.U.; WEINAND, Y. (2012): Holz - Tektonik – Digital. In Bau-Netz pdf Magasin. 253.
FRAMPTON, K. (1995): Studies in Tectonic Culture. The Poetics of Construction in Nineteenth and
Twentieth Century Architecture, Cambridge, MA.
GAWRONSKI, T. (2012): Optimisation of CNC routing operations of wooden furniture parts. The
International Journal of Advanced Manufacturing Technology. DOI 10.1007/s00170-012-46475. 67: pp.2259-2267.
MIJOVIĆ, B.; GRBAC, I.; DOMLJAN D. (2006): 3D geometrijsko modeliranje namještaja. Drvna
industrija 57 (1): pp. 19-27.
PEARSON, D. (2001): The Breaking Wave: New Organic Architecture (Stroud: Gaia), pp. 72.
WIEEDENBECK. J.; PARSONS. J. (2010): Digital technology use by companies in the furniture, cabinet,
architectural millwork, and related industries. Forest Prod. J. 60 (1): pp.78-85.
69
WOOD IS GOOD
Importance of Botanical Binominal Nomenclature for
Hydrothermal Wood Processing
KLARIĆ Miljenkoa – PERVAN Stjepana*
a
Department of Material Technologies, Wood Technology Section, Faculty of Forestry, University of Zagreb,
Zagreb, Croatia
*
Abstract – This research paper reports on importance of botanical binominal nomenclature for wood
trade and its influence on wood processing, especially on hydrothermal wood processing. Introduction
to the basics of botanical binominal nomenclature is made in accordance with latest changes in
International Code of Nomenclature for Algae, Fungi, and Plants (MELBOURNE CODE, 2012). The
usefulness of knowledge about scientific names of wood species for manufacturers and end users is
discussed. Some examples of wood drying defects that can occur due to lack of knowledge on specific
wood specie scientific name are shown and elaborated. Also, a several wood species diversity
comparison within the same genus related to the hydrothermal processing has been made.
botanical binominal nomenclature / hydrothermal wood processing / defects
1. INTRODUCTION
Nowadays, in the times of globalization the lumber trade does not distinguish national
boundaries and has no transportation limitations. Consequentially lumber harvested in North
America or Africa can easily be shipped and processed in Europe or Asia and vice versa,
respectively final wood products can easily be transported from a continent to a continent in
relatively short period of time from producer to a potential buyer. With such international
wood trade possibilities, difficulties emerge easily especially if trading parties are not
adequately trained and have no necessary knowledge in terms of wood properties and
handling. The situation which occurs easily is that the customer get wood product of a wood
specie that was not initially declared, and in such cases, those products are usually made out
of cheaper wood types (not necessarily worse one). ROSS et al. (2005) pointed out that the
name of the wood specie from which the final product is made influences customer choice,
and that there is a discrepancy between the valuation of products based on appearance and on
the name of wood type. In general it is not considered to be a problem if the aesthetic
characteristics of wood products are as the customer expected, and what are the affinities of
customer. Still customer will probably pay higher price for the cheaper wood specie. KLARIĆ
et al. (2012) stated that furniture manufacturers could in that way, by using commercially less
interesting, rarely used, and less expensive species of wood in the production of final products
introduce new trends and maximize profits. These wood species are cheaper, which allows the
final products of lower cost but with the same level of profit. Such action is acceptable if the
customer has also benefited in a way that the final product is slightly cheaper. A more
significant problem with the lack of knowledge of specific wood species is emerging during
hydrothermal wood processing. Because of the great influence of knowing correct specie, and
thereby knowing the scientific name of wood species, imposes a need for basic knowledge of
plant systematics, thereby taxonomy and most important botanical binominal nomenclature.
Therefore, in this research paper an introduction to basics of systematics and botanical
binominal nomenclature are presented along with its influences on hydrothermal wood
processing. Wherein, some specific examples associated to the article topic are elaborated.
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WOOD IS GOOD
2. PLANT SYSTEMATICS AND TAXONOMY
Systematics and taxonomy are terms that are often mixed with each other, and often used
as synonyms. There is a great number of various definitions of systematics. In general,
systematics is the scientific study of organisms biodiversity and its interrelationships through
revelation of the evolutionary history, while plant taxonomy means classification of plants
following certain rules, principles and procedures. The main subjects of taxonomy study are
taxa, which are on principle delimited groups of organisms. In generally systematics is term
that is more inclusive and encompasses traditional taxonomy. Besides it encompasses
taxonomy whose main components are Description, Identification, Nomenclature, and
Classification (DINC), its primary goal is the reconstruction of phylogeny, or evolutionary
history.
Figure 1. Areas of systematics according to STUESSY (1979, 2009)
Phylogeny is a study of genealogy and evolutionary history of a taxonomic group (S INGH,
2010). Usually it is presented in the form of a cladogram or phylogram (Figure 2), which
visualize the evolutionary pattern of decent through branching diagram. The basic difference
between cladogram and phylogram is that the phylogram indicates the degree of relationship
between organisms based upon similarities and differences in their characteristics trough the
distance among them (branches lengths). Respectively phylogram corresponds more closely
to the real elapsed time. As mentioned above, for systematics and taxonomy, cladogram or
phylogram are terms that are also frequently mixed.
Figure 2. Cladogram of the woody and seed plants (source: SIMPSON, 2010)
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WOOD IS GOOD
2.1. Botanical binominal nomenclature
Botanical binominal nomenclature is encompassed by taxonomy and it deals with the
determination and assignment of a correct name for taxa (singular: taxon) or a taxonomic
group. In generally, for different groups of living organisms, there are different rules. Formal
international rules, criteria and recommendations according to which naming plants (including
Algae and Fungi) is based on International Code of Nomenclature or ICN (MCNEILL et al.,
2012) published by the international Association of Plant Taxonomy (IAPT). International
code is updated approximately every six years at each international Botanical Congress,
therefore, before 2012. it was International Code of Botanical Nomenclature or ICBN
(WIENA CODE). ICN is governed according to six principles. The fundamental principle of
nomenclature is that each taxon, whether species, genus, etc., can bear only one correct name
in order to avoid confusion. In accordance with the above mentioned, the name assigned to
individual plant is known as scientific name of the plant and it is binominal, consisting of the
genus name and the specific epithet, which are treated as Latin. Casper Bauhin (1623)
introduced the concept of Binominal nomenclature, but he did not use it. Firmly established
system of naming was set forth by Carolus Linnaeus in his Species planetarum (1753), while
early rules of nomenclature were set in his Critica botanica (1737), and further amplified in
Philosophica botanica (1751) (SINGH, 2010). Taxa ranks are hierarchically arranged by the
system of nomenclature. Taxa ranks in descending sequence are given in Table 1, while the
seven major obligatory ranks are bolded.
Table 1. Taxa ranks for plants in descending sequence according to International Code of
Nomenclature (MCNEILL et al., 2012).
TAXONOMIC RANKS OF PLANTS
latin
english
Regnum
Kingdom
Subregnum
Subkingdom
Phylum [or Divisio]
Phylum [or Division]
Subphylum [or Subdivisio]
Subphylum [or Subdivision]
Classis
Class
Subclassis
Subclass
Ordo
Order
Subordo
Suborder
Familia
Family
Subfamilia
Subfssamily
Tribus
Tribe
Subtribus
Subtribe
Genus
Genus
Subgenus
Subgenus
Sectio
Section
Subsectio
Subsection
Series
Series
Subseries
Subseries
Species
Species
Subspecies
Subspecies
Varietas
Variety
Subvarietas
Subvariety
Forma
Form
Subforma
Subform
Abbreviation
Ending
[cl.]
[subcl.]
[ord.]
[subord.]
[fam.]
[subfam.]
[tr.]
[subtr.]
[gen.]
[subg.]
[sect.]
[subsect.]
[ser.]
[subser.]
[sp.]
[subsp.]
[var.]
[subvar.]
[f.]
[subf.]
various
various
-phyta
-phytina
-opsida
-idae
-ales
-ineae
-aceae
-oideae
-eae
-inae
various
various
various
various
various
various
various
various
various
various
various
various
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3. HYDROTHERMAL WOOD PROCESSING
Angiosperms are higher evolved group of plants than the gymnosperms are, more
precisely conifers. Higher evolutionary development in particular means that angiosperms
have a more complex histological structure. Because of the different histological structure, the
angiosperms are more difficult to dry than gymnosperms. As it was mentioned, there is a
significant difference in histological structure between hardwoods and softwoods, and they
behave differently during kiln drying process. Therefore, hardwood species cannot be easily
dried like softwoods, the drying time is significantly prolonged and the occurrence of defects
is more frequent. There is not just the difference between hardwoods and softwoods but
among each other aswell. The slight difference exists even among the same wood specie.
Hydrothermal treatment of wood is a crucial and a critical step in every wood processing
production. During the hydrothermal treatment of wood, it is necessary to know with great
certainty the specific type of wood specie that is being processed. There may be differences
present within same wood genus that may affect hydrothermal wood processing especially
kiln drying. It is not always the case that the lumber quality is questioned, but often because
of uncertainty about how the lumber will behave, processing regimes that are being used are
milder that they should be, and thereby, drying time is unnecessarily prolonged.
Consequently, hereinafter some examples of differences within same genus among
similar wood species will be analysed and discussed.
3.1. Yellow heartwood discolouration of some wood species
From the practical experience it is known that during air and kiln drying of Pedunculate
oak (Quercus robur L.) and Sessile oak (Quercus petraea (Matt.) Liebl.) yellowish
discoloration of the heartwood may occur, and it mainly appears in the form of streaks in the
direction of the wood fibres (Figure 3). Discoloured streaks are mostly extended from the cut
ends to the interior of the lumber, however, this is not always the case.
Figure 3. Yellow stain streaks on the Quercus robur L. heartwood parquet flooring
(source: Gard et al., 2010)
BAUCH et al. (1991) establish that this kind of discolouration is caused by the mould-type
fungus Paecilomyces variotii Bain. The reacting compounds are probably hydrolysable
tannins, wherein reaction occurs between fungal metabolites and accessory compounds in the
heartwood. The same authors determined that the longitudinally extended yellow
discoloration occurs along and in the vicinity of the vessels, where within earlywood vessels
thick hyphae grow into a netlike mycelium. It can also be localized in the ray and longitudinal
parenchyma. However, this discolouration does not occur in the oak-wood sapwood despite
the fact that the fungi develop in this part of the lumber as well. Paecilomyces variotii Bain. is
a saprophytic fungi that is commonly occurring in air and food and thus lumber is very easily
infected with its spores, because of its common presence in the air. Paecilomyces variotii
Bain. is a thermotolerant and thermophilic type of fungus that was first described by Bainier
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WOOD IS GOOD
in 1907, and from species belonging to Paecilomyces section Paecilomyces it is the most
commonly encountered (LUANGSA-ARD et at., 2004).
Figure 4. Paecilomyces variotii Bain. under light microscope, conidiophores (on the left), phialides
and conidia (on the right). (source: LUANGSA-ARD, et at. 2004)
SIMPSON (1991) states that Paecilomyces variotii Bain., forms lumber discoloration under
warm humid conditions particularly during predrying process if the air circulation is poor.
Therefore, the final quality of the lumber depends on the ways in which raw material is
treated at all stages that precede hydrothermal processing (KLARIĆ et al., 2012).
Figure 5. Yellow stain streaks on the Quercus robur L. heartwood parquet staves (photo: Klarić)
According to practical experience of the authors, Paecilomyces variotii Bain. caused
yellow stains vanish after some time of exposure to the sunlight in internal room conditions.
Figure 5 shows the initial state of yellow stain on the parquet elements and the same strips
after several months of exposure to sunlight in indoor conditions, after the stain is reduced is
shown in Figure 6. One can notice a significant reduction of yellow stain visibility on Figure
5 compared to Figure 6.
Figure 6. Faded yellow stain on the Quercus robur L. heartwood after exposure to the sun light
(photo: Pervan and Klarić)
BAUCH et al. (1991) states that specific reacting heartwood compounds which are
involved in yellow staining, were found in (Quercus robur L.), (Quercus Petrea [Mat.] Liebl.)
and (Castanea sativa Mill.), while in (Quercus rubra L.) heartwood those compounds were
not found. Consequently, it is very important to know accurately which exactly wood specie
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WOOD IS GOOD
is being processed, because in that way the occurrence of yellow staining can be excluded if
we process the wood specie not prone to the yellow staining. Or vice versa, the emergence of
staining can be expected if the wood specie which is prone to the occurrence of the yellow
staining is being processed. Therefore, necessary precautions must be undertaken.
On the other hand, oak-wood heartwood is very susceptible to the cracks and colour
change if it is exposed to high temperatures during initial stage of kiln drying process, while it
still has high moisture content. Therefore, by maintenance of low dry-bulb temperature in
order to avoid cracks and other types of discolouration, fungus may have the ideal prerequisite
in the kiln for the growth, and hence yellow stain can occur during the initial stages of the kiln
drying process. This type of fungus is thermotolerant and thermophilic which additionally
stimulates its development. It can occur not only during the kiln drying, but also during the
certain periods of the year while lumber is air-dried. Yellow stain may also be initiated if
unprofiled stickers are used for lumber stacking. If that is the case, the moisture is retained
below stickers and there is no air circulation and thus, fungus may easily develop.
Figure 7. Yellow stain on the Quercus robur L. heartwood flooring parquet
(source: http://www.myfloor.pl/z-praktyki-rzeczoznawcy-przebarwienia-debu-spowodowane-przezgrzyb-paecilomyces-variotti,509,artykul.html)
Frequently yellow stain occurs on the oak wood floorings, where it is aesthetically very
unacceptable, where furthermore, it can be even more pronounced after lacquering.
3.2. European Larch and Siberian Larch similarities and differences
Larch wood is significant construction and joinery wood source with high potential in
Europe nowadays. Two larch species stand out among others in the same genus, namely,
European larch (Larix decidua Mill.) and Siberian larch (Laix sibirica Ledeb.). Larch wood
has preferred properties for outdoor application, it is partially decay resistant and has
appealing growth ring patterns. According to GIERLINGER et al. (2004) and VENÄLÄINEN et
al. (2006) in Larix species there is correlation between total phenols and decay resistance.
Furthermore, according to POCKRANDT (2012), Siberian larch, when compared with European
larch, has much higher decay resistance in-ground, and some higher decay resistance above
ground. One should take into account that the mentioned experiment was carried out in
Sweden, hence the decay resistance of those two species could differ in warmer parts of
Europe.
Nowadays, larch wood is increasingly used for external doors and windows production.
On the regional lumber market under the same trading name commonly are sold both, the
European larch and the Siberian larch. Traders mostly do not distinguish those two species,
and this can be misleading for the end users. In generally there are no crucial differences for
the joinery production between European larch and Siberian larch. Siberian larch is slightly
more decay resistant and has slightly higher mechanical properties due to its higher density of
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WOOD IS GOOD
wood, what is due to narrower growth rings and higher share of the latewood zone within the
growth ring.
Table 2. Mean annual ring width, mean wood density and latewood proportion of some Larix sibirica
and Larix decidua according to KARLMAN et al. (2005)
Species
L. sibirica
L. decidua
L. decidua
Origin
Krasnoyarsk
(RUS)
Lyrestad
(SWE)
Remningstorp
Mean annual ring
width (year 1-20)
[mm]
Mean annual
ring width
[mm]
2.38
1.08
2.88
1.92
3.62
3.29
Mean density
(min – max)
[kg/m3]
639
(565-670)
621
(550-665)
536
(515-560)
Latewood
proportion
[%]
39
42
34
On the other hand, there is a significant variability in the density of the wood of Siberian
Larch, especially between earlywood and latewood, and also between origins (KOIZUMI et al.,
2003).
Figure 8. Siberian larch cross-section (on the left)(photo: Pervan and Klarić),
European larch (on the right) (source: GODET, 2006)
The problem occurs when the larch wood has to be kiln dried. Siberian larch is more
prone to drying defect occurrence than European larch. Distortion, cracks and especially
micro cracks often occur. Denser wood is more prone to cracks occurrence during drying. The
frequent problem is uneven final moisture content, which can cause problems during gluing
and finishing process. Siberian larch is growing on a large area of the earth northern
hemisphere, and therefore huge differences in properties between trees from different areas
may be present. Siberian larch from the Finland and one from Siberia probably will not
behave in the same way during the hydrothermal processes.
3.3. Tropical woods
In the commercial wood trade on the international market with tropical woods frequently
many different wood species are frequently sold under the same common name. Excellent
example of such case is frequently used common name “African Ebony”. The term African
Ebony represents Diospyros spp. which originates from Africa, and according to KUKACHKA
(1969) this is group of about forty species but only a few produce enough of the darkcoloured heartwood to be of economic importance. CHUDNOFF (1984) states that other
common names for African Ebony are: Mgiriti, Msindi (Tanzania), Omenowa (Ghana),
Kanran, Nyareti (Nigeria), and Kukuo (Gambia). Not only is there African Diospyros spp.,
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there are also Diospyros spp. from equatorial belt all around the world, and if the term Ebony
is used it can represent any of several dozens of wood species.
Figure 9. African Ebony (Diospyros mespiliformis) on the left, Mauritius Ebony (Diospyros melanida)
(source: xylarium of the Department for Wood Scence, Faculty of Forestry, University of Zagreb)
African Ebony heartwood is mostly uniformly dark coloured while Asian Ebony has
lighter colour and is commonly striped. There are some African Ebony species, which can
also be striped, but they are in generally darker coloured than striped Asian Ebony heartwood.
The sapwood of both, African and Asian ebony is significantly lighter coloured and the
difference between heartwood and sapwood is notable. American Diospyros spp. visually
differ significantly from African and Asian Diospyros spp. The Diospyros spp. can be also
completely light coloured, e.g. American Persimmon (Diospyros virginiana L.).
According to the Ministry of Natural Resources and Tourism of The United Republic of
Tanzania, some Tanzanian growing Diospyros spp. together with vernacular names and the
dialect used (in brackets) are listed in Table 3. It can be seen that there are many variations of
vernacular names for the same wood specie within one African Republic. In addition, some
vernacular names embraces several wood species, or the same dialect uses multiple names for
the same species. Likewise, different dialects use the same vernacular name for different
species.
Table 3. Some Diospyros species from Tanzania with local names and dialect used.
Scientific
name
Diospyros
abyssinica
Diospyros
fischeri
Diospyros
mespiliformis
Diospyros
whyteana
Vernacular name
Mkeakiindi
(Shambaa)
Mbonto
(Shambaa)
Mfisha
(Fipa)
Mdengemsitu
(Bena)
Mtitu
(Shambaa)
Mdaa
(Makonde)
Mhena
(Shambaa)
Msisina
(Hehe)
Mnginyei
(Maasai)
Mdaha
(Kwere)
Mkulwe
(Bondei)
Msisina
(Shambaa)
Mfubata
(Nyamwezi)
Msinde
(Nyamwezi)
Mtitu
(Bena)
Mpatilavehe
(Hehe)
Mkea kiindi
(Shambaa)
Mupatilavehe
(Hehe)
Mumbiluilu
(Nyaturu)
Mtitu
(Shambaa)
Similar, encompassing common names are not only the case for the Ebony, but for the
vast number of tropical wood species. Furthermore, most of the tropical woods are difficult to
dry, and are prone to defects, besides from each habitat the drying properties can be
significantly different. Most of the European wood processing companies have no experience
with kiln drying of tropical woods, and additionally, if the exact specie is not identified,
drying defects are unavoidable. The one should be cautious when dealing with Ebony wood.
It is very likely that wood processing company or end user when buying Ebony wood will not
get the texture and colour of Ebony wood they initially desired. A great range of textures and
colours of ebony wood are available on the international market, and the buyer should know
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exactly what his preferences are, what specie or group of species fulfils the criteria, which are
desirable for a specific purpose.
4. DISCUSSION
There are numerous examples of differences in between similar species originating from
the same genus. On the final product those differences are mostly aesthetic, but during the
production they may cause serious problems, such as defect occurrence, higher energy
consumption etc. As regards to the end user, it is important for them to be well informed
about scientific names of wood species before purchasing wooden products or semi products.
If they are not well informed, it may happen that they will get the specie they did not pay for.
During the lumber kiln drying if the exact specie is not known many drying defects can
occur. If the wood specie which is kiln dried is more sensitive to the high initial temperature
or moisture, and the kiln operator does not know that, casehardening, collapse, distortion,
discoloration or cracks may occur. Another example is when the wood specie is not sensitive
to the rapid kiln drying regime, and the operator does not know that, the kiln drying process
will last longer than it should. That means that more electricity and more heat energy will be
consumed, but not only the energy, also the kiln capacity and working time of involved
workers will be lost. If the lumber that will be kiln dried is from and for the third persons than
it is especially important to determine exact wood specie in order to avoid drying defects, and
thus avoid inconveniences and unnecessary costs.
There is a problem concerning vernacular wood species names, because their usage is
confined mostly in a few languages, and they significantly vary not only from language to
language, but also from region to region. Often family or generic relationships are not
indicated via common names. Oak is similarly common name for the species of genus
Quercus, but Tanbark oak is Lithocarpus, Poison oak a Rhus, Silver oak a Grevillea and
Jerusalem oak a Chenopodium (SINGH, 2010).
Common name can also be confusing when a specie has more than one common name
what is especially the case if it is widely distributed in different localities. However, opposite
problem appears when a certain species are so unfamiliar that they do not have common
name.
In the Republic of Croatia there is a nice example of vernacular names for the Alnus
glutinosa [L.] Gaertn., and its historical development, whereby the term “joha” is nowadays
language standard, while term “jalša” is used in northern and western parts of Croatia as a
dialectal and archaic expression. But that was not the case in the past. BALOG (2005) states
that until the 17th century the variant “jalša” prevailed as the standard, and that all of the
earlier confirmed toponyms are being derived from this variant. As a consequence of huge
migrational changes, having to do with the Turkish conquests, “jalša” was evicted to the utter
North and West of Croatia, while the regions in between use “joha”.
5. CONCLUSION
The use of scientific wood species names has many advantages, among which is
international intelligibility. Whenever it is possible, one should use scientific wood species
names to avoid misunderstandings during the international lumber trade. Likewise, especially
during the hydrothermal wood processing and of course, during all stages of wood
manipulation that precede hydrothermal wood processing. In doing so, wood defects
avoidance will be ensured, implementation of prophylactic treatments will be facilitated, and
last but not least, production cost will be reduced.
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WOOD IS GOOD
6. REFERENCES
BALOG, Z. (2005): Jalša ili Joha – Toponomastičke teme. Cris: Journal of the Historical Society of
Križevci 7 (1): pp. 45-52.
BAUCH, J.; v.HUNDT, H.; WEIßMANN, G.; LANGE, W.; KUBEL, H. (1991): On the Cause of the Yellow
Discolorations of Oak Heartwood (Quercus Sect. Robur) during Drying. Holzf. 45 (2): pp. 79-85.
Bortnowski, C. (21. May 2013): My floor.
URL: http://www.myfloor.pl/z-praktyki-rzeczoznawcy-przebarwienia-debu-spowodowane-przezgrzyb-paecilomyces-variotti,509,artykul.html
CHUDNOFF, M. (1984): Tropical Timbers of the World. Agriculture Handbook Number 607. United
States Department of Agriculture, Forest service, United States of America.
GARD, W. F.; GORIŠEK, Ž.; HRČKA, R.; KARASTERGIOU, S.; PERVAN, S.; SKARVELIS, M.; STRAŽE,
A.; TRAVAN, L. (2010): Discolouration of timber in connection with drying. In: Welling, J.: Dried
Timber – how to specify correctly. European Drying Group (EDG) and COST E 53.
GIERLINGER, N.; JACQUES, D.; SCHWANNINGER, M.; WIMMER, R.; PÂQUES, L. E. (2004): Heartwood
extractives and lignin content of different larch species (Larix sp.) and relationships to brown-rot
decay-resistance. Trees 18 (2): pp. 230-236.
GODET, J. D. (2006): Holzführer – Einheimische Holzarten mit Makroaufnahmen. Eugen Ulmer KG,
Stuttgart, Germany. ISBN 978-3-8001-5197-4.
HOUGH, R. B. (2007): The Woodbook. Taschen, Köln, Germany.
KARLMAN, L.; MÖRLING, T.; MARTINSSON, O. (2005): Wood Density, Annual Ring Width and
Latewood content in Larch and Scots Pine. Eurasian Journal of Forest Research 8 (2): pp. 91-96.
KLARIĆ, M.; PERVAN, S.; PREKRAT, S.; BREZOVIĆ, M.; BIOŠIĆ, D. (2012): Oxidative Discolouration
of Alder Wood (Alnus spp.) During Hydrothermal Processing. In: Proceedings of Ambienta 2012
“Wood is Good – With Knowledge and Technology to Competitive Forestry and Wood
Technology Sector”, Croatia, Zagreb, pp. 69-80. ISBN: 978-953-292-026-0.
KOIZUMI, A.; TAKATA, K.; YAMASHITA, K.; NAKADA, R. (2003): Anatomical characteristics and
mechanical properties of Larix sibirica grown in South-Central Siberia. IAWA Journal 24 (4):
pp. 355-370.
KUKACHKA, B. F. (1969): Properties of Imported Tropical Woods. United States Department of
Agriculture, Forest Service, Forest Products Laboratory, Madison, Wisconsin.
LUANGSA-ARD, J. J.; MANOCH, L.; HYWEL-JONES, N.; ARTJARIYASRIPONG, S.; SAMSON, R. A.
(2004): Thermotolerant and Thermoresistant Paecilomyces and its Teleomorphic States Isolated
from Thai Forest and Mountain Soils. Kasetsart Journal 38 (1): pp. 94-101.
MCNEILL, J.; BARRIE, F. R.; BUCK, W. R.; DEMOULIN, V.; GREUTER, W.; HAWKSWORTH, D. L.;
HERENDEEN, P. S; KNAPP, S.; MARHOLD, K.; PRADO, J.; PRUD’HOMME VAN REINE, W. F.;
SMITH, G. F.; WIERSEMA, J. H.; TURLAND, N. J. (2012): International Code of Nomenclature for
Algae, Fungi, and Plants (MELBOURNE CODE), adopted by the Eighteenth International
Botanical Congress Melbourne, Australia, July 2011. Koeltz Scientific Books, Germany, ISBN
978-3-87429-425-6.
POCKRANDT, M. (2012): Durability of Selected Larch Species and Scots Pine (Pinus sylvestris L.)
Heartwood. In: Proceedings of the 8th meeting of WSE: pp. 129-135. Kaunas, Lithuania. ISBN
978-609-02-0581-5.
ROOS, J. A.; DONOVAN, G.; NICHOLLS, D.; (2005): How dose Species Name Affect Consumer Choice?
An Analysis and Implications for Cabinet Door Marketers. Forest Prod. Journal 55 (5): pp. 21-26.
SIMPSON, W. T. (1991): Dry Kiln Operator’s Manual. Chapter 8. Drying defects pp. 179-206. United
States Department of Agriculture, Forest Products Laboratory, Madison, Wisconsin.
SIMPSON, M. G. (2010): Plant Systematics, Second Edition, Elsevier, United States of America. ISBN
978-0-12-374380-0.
SINGH, G. (2010): Plant Systematics – An Integrated Approach, Third Edition, Science Publishers,
United States of America. ISBN 978-1-57808-668-9.
STUESSY, T. F. (2009): Plant Taxonomy – The Systematic Evaluation of Comparative Data. Second
edition, Columbia University Press, New York, USA. ISBN 978-0-231-14712-5.
TRAJKOVIĆ, J. (2013) Personal communication. VENÄLÄINEN, M.; HARJU, A. M.; TERZIEV, N.;
LAAKSO, T.; SARANPÄÄ, P. (2006): Decay resistance, extractive content, and water sorption capacity
of Siberian Larch (Larix sibirica Ledeb.) heartwood timber. Holzforschung 60 (1): pp. 99-103.
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Environmental Impact Assessment as part of Furniture Design
KUTNAR Andrejaa – KUŠAR Tomažb – KITEK KUZMAN Manjab*
b
a
Andrej Marušič Institute, University of Primorska, Koper, Slovenia
Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana,
Slovenia
*
Abstract – With sustainability being the driving force in the world, environmental impact assessment
should be included also in furniture design. In this study design of a bed for elderly people, while
considering the carbon footprint of the selected material - solid beech wood was performed following
the Cradle to Cradle concept. The designed bed was a multifunctional bed that enables the fullfilment
of specific needs of the end - users - senior citizens. Based on the drawings of the bed, the necessary
quantities of the selected material and the amounts of wood residues were determined. For the
designed bed the carbon footprint was calculated following the standard PAS 2050. The results have
shown that the NET carbon footprint of designed bed is negative, due to sequestrated carbon in the
wooden elements of the product. Furthermore, the study showed that coatings and adhesives
considerbly contribute to the carbon footprint, although they have low contribution to the weight of the
whole product. Therefore, it was concluded that coatings and adhesives from renewable resources
should be used to reduce the environmental impact of the designed bed for elderly people.
carbon footprint / furniture design / environmental assessment / cradle to cradle
1. INTRODUCTION
In the past the emergence of inexpensive materials and advanced technology led societies
into mass consumption, generation of enormous amounts of waste and consequently
landfilling. At that time, environmental matters and sustainable development were of low
concern. During the following decade, different environmental disasters reminded the
academicians, politicians, the media, and society in general to think about such issues like oil
catastrophes, green-house-effects and dying forests. Terms like recycling, reuse, resource
reduction, environmental manufacturing responsibility and green products began to be
familiar to all of us.
Today, a lot of wooden products that could be utilized in a secondary product life cycle
are burned for the production of energy or are just down-cycled so that they are losing the
favourable material properties of solid wood. On one hand, this reduces the competitiveness
of wood as a construction or raw material not only from the ecological, but also from the
business point of view. On the other hand, it offers an obvious opportunity for innovative
companies to create new business models, processes, and products. One of them can be found
in the area of wooden product cycling with continuous loops in production, following the
Cradle to Cradle (C2C) concept, developed by William McDonough and Michael Braungart
(VEZZOLI et al., 2010). The C2C concept is a shift from eco-efficiency towards ecoeffectiveness with continuous loops in production. It is not about doing more with less and
reducing waste (cradle to grave), but about “doing it right” from the beginning. Materials
should circulate in continuous loops and the waste of one process becomes the “food” for
another process.
With regard to greenhouse gas (GHG) emissions, wood is a better alternative than other
materials (less SO2 emissions, less waste) (PETERSEN – SOLBERG, 2005). However, treated
wood, wood bonded by synthetic adhesives and coated wood (synthetic coatings), on the
other hand, might have toxicological impacts on human health and ecosystems. The fossil fuel
consumption, potential contributions to the greenhouse effect and quantities of solid waste
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WOOD IS GOOD
tend to be minor for solid wood products, compared to the competing ones (WERNER –
RICHTER, 2007). In contrast, wood based composites, such as particle boards or fibreboards,
which make use of a larger share of wood of a tree, compared to solid wood products, have a
high consumption of fossil energy associated with the production of fibres and particles/chips,
as well as with the production of glues, resins, etc. (WERNER – RICHTER, 2007). Therefore, the
renewable energy should rather be used to produce wood-based products.
When developing Cradle to Cradle products also social responsibility has to be included
in the design. To respect diversity in designing a product means to take into consideration not
only how it is made but also who will use it and how, in different ways, places and moments.
This principle can be followed in many ways. For example, products can enable that they are
adapted and changed in relation to different phenomena: technology evolves but the
environmental context in which the product is used, and the physical and cultural
characteristics of the user, can evolve as well. Upgradability and adaptability should then be
facilitated and it is necessary to design flexible, modular and reconfigurable products, in
relation to dimensions, performance and appearance. For example, furniture for elderly people
should be designed in a way that it is anthropometrically and ergonomically adjusted to them.
The design should include both safety and functionality and incorporate the specific needs of
the end-users - senior citizens, who often require aid at home and have different design needs
than those who are capable of living by themselves.
Owing to an increasingly higher standard of living as well as improvements in health
care, the proportion of senior citizens in the general population is rapidly increasing.
Statistical prognosis indicates that, by 2030, 36 % of people will be over the age of 60
(HILDERBRAND, 2002). Information from the Statistical Office of the Republic of Slovenia
states that, in 2010, the percentage of Slovenian citizens over 60 years of age was 22 %, out of
which 58 % were female. There had also been an increase in the number of citizens with sight
issues, hampered movement capabilities, and degrees of memory loss. According to data
issued by the Statistical Office of the Republic of Slovenia, citizens over the age of 60
accounted for only 12 % of the changes made to residences in 2008. Other data suggests that
senior citizens rarely decide to change their home environments, which contribute to a
lowering of comfort levels and environments ill–suited for accommodating residents with
special needs, and to lower safety levels. Most people are also reluctant to live in a retirement
home, and only do so when they are entirely incapable of living by themselves. In Slovenia,
7 % of the population resides in a retirement home. However, in 2011 the number of elderly
people that lived in a retirement homes and other social welfare institutions increase in
comparison to the year 2010 by more than 4 %. For the year 2011 the statistics are reporting
22921 people living in retirement homes and social welfare institutions. Additionally,
according to research Home REMODELLING (2006), 60 % of the senior population lives in
homes that have not been renovated or refurnished for over 20 years, contributing to lower
safety and comfort levels. Comfort is crucial for the elderly, as they spend most of their time
at home. Over 14 % of English elder citizens live in unfit conditions, in homes that are in dire
need of renovation and adaptation (BOYO, 2001). Yet only 10 % of them decide to modify
their existing furniture and equipment to reflect their special needs (GILDERBLOOM et al.,
1996). They often refrain from renovating due to financial concerns, lessening mobility and
fear of the upheaval of renovation work. Furthermore, the research also shows that the elderly
also suffer from inappropriate room dimensions including rooms that are too big for them
(WEST – EMMITT, 2004).
Following the C2C this study aimed to design flexible, reconfigurable, healthy, and safe
bed out of solid beech wood with “zero waste”, which involves substitution of toxic elements,
material reutilization, renewable energy use, water stewardship, and social responsibility, and
at the same time enables the assistance to elderly people with changing needs.
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WOOD IS GOOD
2. METHODOLOGY OF CARBON FOOTPRINT CALCULATION
2.1. Goal and scope of the Carbon Footprint Calculation
Following the common Life Cycle Assessment (LCA) methodology (ISO 14044, PAS
2050) the goal of the study was to objectively prove environmental impact from “cradle to
gate”, an assessment of a partial product life cycle from manufacture ('cradle') to the factory
gate (i.e., before it is transported to the consumer), of designed bed for elderly people. The
main focus was given to the carbon footprint. The functional unit was chosen to be the whole
bed.
The use phase and disposal phase of the product were omitted. Analysis included carbon
emissions of raw materials and waste resulting from product production, while transportation
of materials to the factory, electricity and other energy sources in product production were not
included in the calculation.
2.2. Analysed product and data collection
The bed was designed keeping in mind the comfort and needs of old and ailing people.
The conflict between designing for an individual and designing for a population was faced: a
product that suits one person may be inconvenient to another. The ergonomic approach to
home design may develop an integrated strategy aimed at the well being and satisfaction of
ageing people (PINTO et al., 2000). Common habits of elderly people were analysed to design
a bed that meet their changing needs. In bed, ageing people are liable to risks of falls and
impacts. Furthermore, the mobility and physical ability of elderly people are changing over
time. Therefore, the simple multifunctional bed that gives warm feeling of familiarity and
orientation with the environment was designed. The design included the following
requirements: the option to adjust height, maintaining person position, moving and turning
part of bed, raising head and legs, bed rail, vertical grab pole, bed accessories should enable
eating and other activities in bed, while all the appliances should be easy to use involving
simple commands.
The designed bed (width 90 cm, length 200 cm, and height 45 cm) that included the
above requirements is shown in Figure 1. The selected construction material was beech
(Fagus sylvatica). The elements of the designed bed, their dimensions, and needed volume of
wood for each element, accounting also the yield, are given in Table 1.
Figure 1. Bed for elderly people designed following the C2C concept
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WOOD IS GOOD
Table 1. List of solid wood elements, their dimensions, and amount of material needed for designed
bed.
Elements
Dimensions
Leg - headboard
Leg -footboard
Headboard
Trapeze bar
Food board
Board
Side rail
Rail
Length
[mm]
1200
750
900
900
900
2030
1950
2030
Width
[mm]
40
40
900
170
570
200
30
70
Height
[mm]
40
40
20
25
20
20
30
20
Number
of
pieces
2
2
1
1
1
2
2
2
Volume
(net)
Yield
[m3]
0.0038
0.0024
0.0162
0.0038
0.0103
0.0162
0.0035
0.0057
[%]
60
60
60
60
60
60
60
60
Needed
volume
accounting
yield
[m3]
0.0064
0.0040
0.0270
0.0064
0.0171
0.0271
0.0059
0.0095
Following the elements given in Table 1, the list of materials needed for production of
designed bed was determined. The amounts of materials were assessed and used for carbon
footprint and net carbon foot print calculation (Table 2).
Table 2. List of input materials for calculation of carbon footprint and their quantities for the designed
bed for elderly people
Input materials
Solid wood
Metal conecting elements
Metal swivel clamp
Adhesive PVA
Water based coating
0.103 m3
128 g
70 g
200 g
1 450 g
Based on the determined goal and scope of the study, the life cycle inventory of
input/output data for the carbon footprint calculations was performed. Data of energy inputs,
raw materials, products, co-products, waste, and releases to air, water and soil were assessed.
The upstream life cycle impacts of input materials were not analysed specifically for this
project. Instead, sound secondary life cycle data (emission factors) were sourced from
Ecoinvent database 2.0. (2010).
2.3. Modelling and impact assessment
The data collected were modelled in Simapro (SimaPro Analyst Indefinite, Ecoinvent v2,
Product Ecology Consultants, PEC, Netherlands). Emissions and consumptions were
translated into environmental effects, which were grouped and weighed. The biotic carbon
sequestration was considered in the calculation. Carbon footprint was calculated with
methodology IPCC 2001 GWP 100a V1.02 (CLIMATE CHANGE, 2001). IPCC 2007 contains
the climate change factors of IPCC with a timeframe of 100 years. IPCC characterization
factors for the direct (except CH4) global warming potential of air emissions. They do not
include indirect formation of dinitrogen monoxide from nitrogen emissions, do not account
for radiation forcing due to emissions of NOx, water, sulphate, etc. in the lower stratosphere +
upper troposphere, do not consider the range of indirect effects given by IPCC, and do not
include indirect effects of CO emissions.
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WOOD IS GOOD
3. RESULTS
Carbon footprint calculates the amount of green house gas (GHG) emissions caused by a
particular activity or entity, commonly also referred to as global warming potential (GWP). It
is measured in tones (or kilograms) of carbon dioxide equivalent (CO2eq.). Approximately
50 % of dry timber is elemental carbon; thus, 1 kg of wood contains approximately 0.5 kg of
carbon, which equates to 1.83 kg of CO2. When calculating a carbon footprint, whether to
include this stored carbon in timber (and, to a far lesser extent, small amounts of stored
carbon in other materials) is a much debated issue. In this study, the carbon footprint and NET
carbon footprint were calculated. The carbon footprint of the designed bed analysed product
was 10.4 kg CO2e, while the NET carbon footprint was – 107.4 kg CO2e due to carbon
storage (sequestration) in the product, which was 117.8 kg CO2e (Table 3).
Table 3. Carbon footprint, CO2eq sequestered in the product, and NET carbon footprint of designed
bed for elderly people
Carbon footprint
[kg CO2e]
10.4
Bed for elderly
CO2eq. sequestered in
the product
[kg CO2e]
117.8
NET carbon footprint*
[kg CO2e]
- 107.4
* includes carbon storage (sequestration)
In Table 4 and Figure 2, the contributions of input materials to carbon footprint are given.
Although the water-based coating presented low contribution to the weight of the whole
product (2.2 %), it contributed a significant 29.5 % to the carbon footprint. On the other hand,
the timber presented high contribution to the weight of the product (97.2 %), but it
contributed only 63.9 % to the carbon footprint of the designed bed for elderly people.
Furthermore, metal parts and adhesive contributed 3 % to the carbon footprint of the designed
bed for elderly people.
Table 4. Carbon footprint of emission sources and their contribution to the total carbon footprint of
designed bed for elderly people
Input materials
Sawn timber, hardwood, raw, air / kiln dried, u=10 %
Polyvinyl chloride resin
Steel, converter, unalloyed,
Acrylic dispersion, 65 % in H2O
Total
Sawn timber, hardwood,
raw, air / kiln dried,
u=10%
Polyvinyl chloride resin
30%
3%
3%
kg CO2e
6.65
0.359
0.317
3.07
10.4
64%
Steel, converter,
unalloyed,
Acrylic dispersion, 65% in
H2O
Figure 2. Contribution of emission sources to carbon footprint of the “bed for elderly people”.
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WOOD IS GOOD
4. CONCLUSIONS
The study showed that coatings and adhesives considerably contribute to the carbon
footprint, although they have low contribution to the weight of the whole product. Therefore,
coatings and adhesives from renewable resources should be used to reduce the environmental
impact of the designed bed for elderly people. Furthermore, the study demonstrated that the
LCA is a rational, quantified approach to determining specific environmental impacts of a
product. As solutions are sought to reduce the impacts of products, LCA is seen as an
objective measure for comparing products designs. LCA clearly has an important role to play
in assessing the sustainability of green products and it is a valuable tool. The adoption of lifecycle approach to design, where not only current energy concerns are accounted for, but also
long-term energy, environmental, and social impacts, should lead to an integrated approach to
design. Future research will investigate the bed for elderly people made out of a solid beech
wood in combination with veneered particleboard, and out of a solid beech wood in
combination with beech plywood with the aim to determine the best solution, when the
environmental impact is the measure of a material selection process, including the energy use
of the production process. Furthermore, the prototype of multifunctional bed will be produced
and simulation results will demonstrate the effectiveness of the proposed design.
Acknowledgements: We wish to thank the Slovenian Research Agency within the frame of
program P4-0015.
5. REFERENCES
BOYO, S. (2001): When a house is not a home. Older People and their housing, London: AGE – Age
Concern England: 65.
ECOINVENT 2.0 (2010): Swiss Centre for Life Cycle Inventories, Dübendorf, Switzerland.
GILDERBLOOM, J.I.; AFFAIRS, U.; MARKHAM, J.P. (1996): Housing Modifi cation Needs of the
Disabled Elderly: What Really Matters?. Environment and Behavior 28(4): pp. 512-535.
HILDERBRAND, H. 2002: Fur Altere und Behinderte. BM 57 (3): pp. 36
HOME REMODELING (2005): Why Is Home Modification And Repair Important?
URL: http://www.aoa.gov/ eldfam/Housing/Home_Remodeling/Home_Remodeling.asp
ISO STANDARD 14040 (2006): Environmental management - Life cycle assessment - Principles and
framework.
ISO STANDARD 14044 (2006): Environmental management - Life cycle assessment - Requirements and
guidelines.
MEZZOLI, C.; ORBETEGLI, L.; CORTESI, S. (2010): C2C Network, Prospective Study: Industry.
URL: http:// www.c2cn.eu
PAS 2050 (2011): Specification for the assessment of the life cycle greenhouse gas emissions of goods
and services. BSI, UK.
PETERSEN, A.K.; SOLBERG, B. (2005): Environmental and economic impacts of substitution between
wood products and alternative materials: a review of micro-level anayses from Norway and
Sweden. Forest Policy and Economics 7: pp. 249-259.
PINTO, M.R.; DE MEDICI, S. (2000): Ergonomics, gerontechnology, and design for the home
environment. Applied Ergonomics 31 (3): pp. 317-322.
SIMPRO (2009): SimaPro Analyst Indefinite, Ecoinvent v2, Product Ecology Consultants, PEC,
Nizozemska. URL: http:// www.pre.nl/default.htm
STATISTIC OFFICE (2010): POPIS 2002.
URL: http://www.stat.si/popis2002/si/rezultati/rezultati_red.asp?ter=SLO&st=44
WERNER, F.; RICHTER, K. (2007): Wood building products in comparative LCA. A literature review.
Int J LCA, 12 (7): pp.470-479.
WEST, B.N.; EMMITT, S. 2004: Functional design? An analysis of new speculative house plans in the
UK. Design Studies 25: pp. 275-299.
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WOOD IS GOOD
Comparative Analysis of Stiffness Coefficients of End and T-shape Corner
Joints of Frame Structural Elements with Two Types of Cross Sections
made of Sweet Chestnut Wood
KYUCHUKOV Georgia – GRUEVSKI Georgib – MARINOVA Assiaa – KYUCHUKOV Borislava
JIVKOV Vassila*
a
b
University of Forestry, Sofia, Bulgaria
Ss. Cyril and Methodius University, Skopje, R. of Macedonia
*
Abstract – The present study involves a comparative analysis of experimentally established stiffness
coefficients under compression bending test of some of the most frequently used end and T-shape
corner joints of frame structural elements with two types of rectangular cross sections – with size of
50x25 mm and 50x30 mm, made of sweet chestnut solid wood. It was established that the type of the
joints has a determining influence on their stiffness characteristics. The T-shape corner joints have on
average 7.6 % and 11.2 % greater stiffness coefficient then the one of the end corner joints
respectively for thickness of the elements 25 and 30 mm. With an increase of the thickness of the cross
section from 25 mm to 30 mm, the stiffness coefficient of the end and T-shape corner joints increases
on average by about 27 % and 32 %, respectively. It is recommended that the stiffness coefficients of
the tested corner joints have to be taken into account when choosing the type of joints in the chair
constructions.
end and T-shape corner joints / structural elements / stiffness coefficients / compression bending
test / chair constructions / sweet chestnut solid wood
1. INTRODUCTION
The stiffness characteristic of the corner joints is one of the main factors determining the
shape stability of the sitting furniture constructions, as well as their stability and durability at
service use. The stiffness characteristic depends on a number of factors – the tree species and
physical and mechanical properties of wood, the cross section of the joined structural
elements, the type and parameters of the joints, the properties of the glue line of the joints, the
joints’ tightness, the roughness of the contacting surfaces of the joined structural elements,
etc. Given this, in the research laboratories for furniture structural design, tests are
consistently carried out on the ultimate bending moments and stiffness coefficients of the
corner joints of the sitting furniture constructions, simulating service load (ALBIN et al., 1986;
ERDIL et al., 2005; GRUEVSKI, 2007; JIVKOV, 2001; KYUCHUKOV et al., 2008a; KYUCHUKOV
et al., 2008b; KYUCHUKOV et al., 2009; KYUCHUKOV et al., 2010; KYUCHUKOV et al., 2011a;
KYUCHUKOV et al., 2012a; KYUCHUKOV et al., 2012b; TANKUT et al., 2005, ZHANG et al.,
2001). It is relatively rare to find scientific studies about stiffness characteristics of these types
of corner joints. To this end, the present study is designed to do a comparative analysis of
experimentally established stiffness coefficients under compression bending test of some of
the most frequently used end and T-shape corner joints of frame structural elements with two
types of rectangular cross sections – with size of 50x25 mm and 50x30 mm, made of sweet
chestnut solid wood.
The type of the tested corner joints of the frame structural elements are sketched in
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WOOD IS GOOD
Figure 1 and Figure 2. The type, shape and dimensions of the samples (Figure 3), as well as
their preparation, conditioning and testing under compression bending load were described in
the previous publications (GRUEVSKI, 2007; JIVKOV, 2001; KYUCHUKOV et al., 2008a;
KYUCHUKOV et al., 2008b; KYUCHUKOV et al., 2009; KYUCHUKOV et al., 2010; KYUCHUKOV
et al., 2011a).
Figure 1. End corner joints of structural elements made of sweet chestnut solid wood:
Glued corner joints: 1 – open mortise and tenon joint; 2 – half-open mortise and tenon joint;
3 – haunched mortise and tenon joint; 4 – mortise and tenon joint; 5 – joint with two dowels ϕ 10 mm;
6 – joint with wooden “Lamello plates”
Disconnected corner joints: 7 – joint with two countersunk screws for wood; 8 – joint with two onepiece connectors “Confirmat”; 9 – joint with two connectors with screw and cross dowel
Figure 2. T-shape corner joints of structural elements made of sweet chestnut solid wood:
Glued corner joints: 1 – stub mortise and tenon, type A; 2 – through mortise and tenon type A;
3 – stub mortise and tenon with shoulders, type B; 4 – through mortise and tenon with shoulders,
type B; 5 – joint with two dowels ϕ 10 mm; 6 – joint with wooden “Lamello plates”
Disconnected corner joints: 7 – joint with two countersunk screws for wood; 8 – joint with two onepiece connectors “Confirmat”; 9 – joint with two connectors with screw and cross dowel
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WOOD IS GOOD
Figure 3. Dimensions and testing schemes of the samples under compression
bending load: a and b – end corner joints; c and d – T-shape corner joints
3. COMPARATIVE ANALYSIS OF THE RESULTS
Comparative data of the results from the experimental studies on the stiffness coefficients
of the tested corner joints is presented in Table 1. Figure 4 and Figure 5 give a graphical idea
of the ratio of the stiffness coefficients of the tested types of corner joints.
The data indicates that the type of joints has a determining influence on their stiffness
coefficients under bending load.
Figure 4. Comparative data of the stiffness coefficients of the tested end corner joints of structural
elements with cross section of 50 x 25 mm and 50 x 30 mm made of sweet chestnut solid wood
according to Table 1
According to the stiffness coefficients’ values, the glued end corner joints (Figure 1) with
rectangular cross section of 50x25 mm are set in the following hierarchical order: open
mortise and tenon joint, half-open mortise and tenon joint, haunched mortise and tenon joint,
mortise and tenon joint, joint with two dowels φ 10 mm and joint with wooden “Lamello
plates”. Among the tested dismountable end corner joints with cross section of 50x25 mm, the
joint with two one-piece connectors “Confirmat” has the highest stiffness coefficient,
followed by the joint with two counter-sunk screws for wood and the joint with two
connectors with screw and cross dowel.
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WOOD IS GOOD
Table 1. Stiffness coefficients under compression bending loading of the corner joints of structural
elements with rectangular cross section 50x 25 mm and 50 x 30 mm made of sweet chestnut solid
wood
Type of the corner joints
A. End corner joints
I. Glued corner joints
1. Open mortise and tenon joint
2. Half-open mortise and tenon joint
3. Haunched mortise and tenon joint
4. Mortise and tenon joint
5. Joint with two dowels φ 10 mm
6. Joint with wooden “Lamello plates”
II. Dismountable corner joints
7. Joint with two counter-sunk screws for wood
8. Joint with two one-piece connectors “Confirmat”
9. Joint with two connectors with screw and cross dowel
B. T-shape corner joints
I. Glued corner joints
1. Stub mortise and tenon joint, type A
2. Through mortise and tenon joint, type A
3. Stub mortise and tenon with shoulders, type B
4. Through mortise and tenon with shoulders, type B
5. Joint with two dowels φ 10 mm
6. Joint with wooden “Lamello plates”
II. Dismountable corner joints
7. Joint with two counter-sunk screws for wood
8. Joint with two one-piece connectors “Confirmat”
9. Joint with two connectors with screw and cross dowel
Stiffness coefficients for cross sections
of the structural elements:
50 x 25 mm,
50 x 30 mm, Ratio
c1, N.m/rad
c2/c1
c2, N.m/rad
8 060
7 800
7 700
7 500
7 060
6 000
9 850
9 600
9 470
9 240
8 930
8 040
1,22
1,23
1,23
1,23
1,26
1,34
3 500
4 200
3 400
4 480
5 540
4 420
1,28
1,32
1,30
8 080
8 610
7 500
7 580
7 080
6 020
10 260
11 760
9 820
10 360
8 980
8 920
1,27
1,37
1,31
1,37
1,27
1,48
3 810
4 850
4 370
5 040
5 620
5 870
1,32
1,16
1,34
According to the stiffness coefficients’ values, the glued T-shape corner joints (Figure 2)
with rectangular cross section of 50x25 mm are set in the following hierarchical order:
through mortise and tenon joint, type A; stub mortise and tenon joint, type A; through mortise
and tenon joint with shoulders, type B; stub mortise and tenon joint, type B; joint with two
dowels φ 10 mm; joint with wooden “Lamello plates”. Among the tested dismountable Tshape corner joints with cross section of 50x25 mm, the joint with two one-piece connectors
“Confirmat” has the highest stiffness coefficient, followed by the joint with two connectors
with screw and cross dowel and the joint with two counter-sunk screws for wood.
According to the stiffness coefficients’ values, the glued and dismountable end corner
joints (see Figure 1) with rectangular cross section of 50x30 mm are set in the same
hierarchical order as the joints of structural elements with size of cross section 50x25 mm.
Among all tested glued T-shape corner joints (Figure 2) with cross section of 50x30 mm,
the through mortise and tenon joint, type A, has the highest stiffness coefficient. Following in
a decreasing order are the through mortise and tenon joint with shoulders, type B, the stub
mortise and tenon joint, type A, the stub mortise and tenon joint, type B, the joint with two
dowels f 10 mm, and the joint with wooden “Lamello plates”. Among the tested dismountable
corner joints with cross section of 50x30 mm, highest is the stiffness coefficient of the joint
with two connectors with screw and cross dowel, followed by the joint with two one-piece
connectors “Confirmat” and the joint with two counter-sunk screws for wood.
90
WOOD IS GOOD
14000
С1, С2, Nm/rad
Cross section 50х25 mm
Cross section 50х30 mm
11760
12000
10260
10000
8080
9820
8980
8610
7500
8000
10360
8920
7580
7080
6020
5040 4850
4370
3810
4000
5870
5620
6000
2000
0
1
2
3
4
5
6
7
8
9
Type of corner joints
Figure 5. Comparative data of the stiffness coefficients of the tested T-shape corner joints of structural
elements with cross section of 50 x 25 mm and 50 x 30 mm made of sweet chestnut solid wood
according to Table 1
The difference in the hierarchical order of the stiffness coefficients of all tested end and
T-shape corner joints of structural elements with rectangular cross section of 50x30 mm in
comparison with those with rectangular cross section of 50x25 mm is a result of the different
mode of failure in the joints. The bigger thickness of the structural elements results in
proportionately fewer wood failures of the structural elements compared to failures of their
joining elements.
The data in Table 1 also indicates that the cross section of the structural elements
influences significantly the stiffness characteristic under bending load of the corner joints.
The ratio between the stiffness coefficients of the glued end corner joints of structural
elements with cross section of 50x30 mm and 50x25 mm, respectively, is on average 1.25, i.e.
increasing of the cross section’s thickness from 25 mm to 30 mm increases the stiffness
coefficient by about 25 %. The ratio between the stiffness coefficients of the dismountable
end corner joints of structural elements with cross section of 50x30 mm and 50x25 mm, is on
average 1.30, i.e. increasing of the cross section’s thickness from 25 mm to 30 mm increases
the stiffness coefficient by about 30 %. The average increase of the stiffness coefficients of
the glued and dismountable end corner joints is about 27 %.
The ratio between the stiffness coefficients of the glued T-shape corner joints of
structural elements with cross section of 50x30 mm and 50x25 mm, respectively, is on
average 1.34, i.e. increasing of the cross section’s thickness from 25 mm to 30 mm increases
the stiffness coefficient by about 34 %. The ratio between the stiffness coefficients of the
dismountable T-shape corner joints of structural elements with cross section of 50x30 mm
and 50x25 mm, is on average 1.27, i.e. increasing of the cross section’s thickness from 25 mm
to 30 mm increases the stiffness coefficient by about 27 %. The average increase of the
stiffness coefficients of the glued and dismountable T-shape corner joints is about 32 %.
4. CONCLUSION
The results of the comparative analysis of the stiffness coefficients under compression
bending test of the most frequently used end and T-shape corner joints of frame structural
elements with two types of rectangular cross sections – with size of 50x25 mm and 50x30 mm
- made of sweet chestnut solid wood gave reason to the following general conclusions and
recommendations:
91
WOOD IS GOOD
1. The type of the joints has a determining influence on their stiffness characteristics under
bending load.
2. The size of the cross section of the structural elements influences considerably the
stiffness coefficient of the joints. An increase of the cross section’s thickness from 25 mm
to 30 mm increases the stiffness coefficient of the end glued and dismountable corner
joints by about 25 % and 30 %, respectively, (or about 27 % on an average). For the Tshape corner joints the corresponding increases are 34 % and 27 %, respectively, (or
about 32 % on an average).
3. It is recommended that the size of the cross section of the structural elements of the
corner joints made of solid wood and their stiffness coefficients under bending load be
taken into account when choosing the type of the joints in the construction of the
designed models of sitting furniture, as well as at strength and stiffness dimensioning of
this kind of furniture.
5. REFERENCES
ALBIN, R.; SCHMELMER, B. (1986): Beigefestigkeit von gedübelten Verbindungen bei Gestellmöbeln.
Holz als Roh- und Werkstoff 44 (2): p.76.
ERDIL, Y.; KASAL, A.; ECKELMAN, C. (2005): Bending Moment Capacity of Rectangular Mortise and
Tenon Furniture Joints. Forest Products Journal 55 (12): pp.209-213.
GRUEVSKI G. (2007): Izstrajuvanja na sostavite vo konstruktsiite na stolovi izraboteni od kostenovo
drwo, Doktorska disertacia, Faculty of Forestry, Skopje.
JIVKOV, V. (2001): Influence of the tolerances on the strength characteristics of the main glued joints
of furniture. Ph.D thesis, University of Forestry, Sofia.
KYUCHUKOV, G.; GRUEVSKI, G.; MARINOVA, А.; KYUCHUKOV, B. (2008a): Stiffness Coefficients
under Bending Test of End Corner Joints of Frame Structural Elements made of Sweet Chestnut
Wood. In: Proceedings of the 7th International Symposium “Furniture 2008”, Faculty of Wood
Science and Technology, Zvolen, Slovakia, ISBN 978-80-228-1839-1.
KYUCHUKOV, G.; GRUEVSKI, G.; MARINOVA, А.; KYUCHUKOV, B. (2008b): Stiffness Coefficients
under Bending Test of T-shape Corner Joints of Frame Structural Elements made of Sweet
Chestnut Wood. In: Proceedings “Innovation in Woodworking Industry and Engineering Design”,
University of Forestry, Sofia, November 2008: pp. 265-270.
KYUCHUKOV, G.; GRUEVSKI, G.; MARINOVA, А.; KYUCHUKOV, B. (2009): Comparative Analysis of
Stiffness Coefficients of End and T-shape Corner Joints of Frame Structural Elements made of
Sweet Chestnut Wood. In: Proceedings of the 20th International Scientific Conference, University
of Zagreb, October 2009: pp. 101-104.
KYUCHUKOV, G.; GRUEVSKI, G.; KYUCHUKOV, B. (2010): Comparative Studies on Destructive
Bending Moments of End Corner Joints of Components of Solid Chestnut Wood with a Cross
Section of 50 x 25 mm. In: Proceedings “Innovation in Woodworking Industry and Engineering
Design”, Sofia, November 2010: pp. 206-210.
KYUCHUKOV, G.; GRUEVSKI, G.; MARINOVA, А.; KYUCHUKOV, B.; JIVKOV, V. (2011a): Stiffness
Coefficients under Bending Test of End Corner Joints of Structural Elements made of Sweet
Chestnut Wood. In: Proceedings of the 22th International Scientific Conference, University of
Zagreb, October 2011: pp. 89-97.
KYUCHUKOV, G.; KYUCHUKOV, B.; JIVKOV, V.; MARINOVA, А. (2011b): Physical and Mechanical and
Technological Properties of Wood of Some Valuable Tree Species in Bulgaria. Monograph,
Avangard Prima, Sofia, 232 p.
KYUCHUKOV, G.; GRUEVSKI, G.; MARINOVA, А.; KYUCHUKOV, B.; JIVKOV, V. (2012a): Stiffness
Coefficients under Bending Test of T-shape Corner Joints of Frame Structural Elements with
Cross Section of 50 x 30 mm made of Sweet Chestnut Wood. In: Proceedings of the 23-rd
International Scientific Conference, University of Zagreb, October 2012: pp. 97-102.
KYUCHUKOV, G.; GRUEVSKI, G.; KYUCHUKOV, B. (2012b): Comparative Studies on Destructive
Bending Moments of T-shape Corner Joints of Frame Structural Elements made of Sweet
92
WOOD IS GOOD
Chestnut Wood with a Cross Section of 50 x 25 mm. In: Proceedings “Innovation in
Woodworking Industry and Engineering Design”, Sofia, 1/2012: pp. 79-85.
TANKUT, A.; TANKUT, N. (2005): The Effects of Joints Forms and Dimensions on the Strengths of
Mortise and Tenon Joints. Turkish Journal of Agricultural and Forest 29: pp. 493-498.
ZHANG, J.; QUIN, F.; TACKETT, B. (2001): Bending Strength and Stiffness of Two-Pin Dowel Joints
Constructed of Wood and Wood Composites. Forest Products Journal 51 (2): pp. 29-35.
DER GROßE HÄFELE, (2012): Möbelbeschläge. Katalog, Nagold.
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WOOD IS GOOD
Durability of Waterborne Coating Systems for Wooden Windows
MIKLEČIĆ Josipa*– JIROUŠ-RAJKOVIĆ Vlatkaa – ŠPOLJAR Marina
a
Department for Furniture and Wood Products, Faculty of Forestry, University of Zagreb, Zagreb, Croatia
*
Abstract – Artificial weathering method in accordance with HRN EN 927-6 was used for the
evaluation of the behaviour of coating systems for wooden windows. Three opaque waterborne
coating systems and three semi-transparent coating systems were used in this research. The test was
carried out on test specimens made of spruce wood. Surface properties of used coating systems were
compared with ICP (Internal Comparison Product). The best performance of semi-transparent coatings
in terms of colour retention, adhesion and liquid water absorption showed the cheapest coating system.
It has been established that exposure period of 6 weeks was too short to predict performance of opaque
coatings. Obtained results could be used as pre-test for natural weathering.
artificial weathering / waterborne coatings / wooden windows
1. INTRODUCTION
Wood undergoes dimensional changes when exposed to moisture, it is susceptible to
biological attack and it degrades when is exposed to solar ultra violet radiation. These
shortcomings have driven many homeowners and builders to switch to other frame materials.
To ensure long term performance, in both interior and exterior situations wood needs to be
protected by appropriate coating system. All coating systems have numerous properties which
must be optimized if they are to perform well. These include drying and recoat times,
application, storage characteristics and many others. In addition coatings for wood have a
number of special requirements relating to permeability, extensibility, adhesion and fungicidal
properties (GRAYSTONE, 1985). It should be emphasized that coating is not designed to
correct possible construction failures, but simply to protect wood from moisture and
ultraviolet light. Coatings can be divided into water-borne and solvent-borne categories.
Waterborne coatings are becoming more popular, partly due to the new environmental rules
and partly because of the fact that they are convenient to use. The performance and durability
of waterborne coatings are not extensively studied as those of conventional solvent-borne
coatings. However, confidence in the durability of waterborne coating materials for wood
joinery is the foundation to compete with plastic and aluminium windows that are based on
non-renewable resources (DE WINDT et al., 2006). When selecting an exterior wood coating,
appearance, durability, cost, surface type, ease of application, and maintenance should be
considered (KNAEBE, 1995). The suitability of coating material for a given end-use situation
should be confirmed by the appropriate performance test. The traditional way of performing
assessment of durability for a coating system is to expose the specimens to natural or artificial
climate.
In this paper assessment of durability of semi-transparent waterborne coating systems and
opaque waterborne systems with different price tags was performed using artificial
weathering method according to HRN EN 927-6. Based on our previous research (J IROUŠRAJKOVIĆ et al., 2005; MIKLEČIĆ – JIROUŠ-RAJKOVIĆ, 2011) the most prominent changes
during accelerated QUV exposure appeared after 6 weeks, so we wanted find out if it was
possible to rank the coatings according to the assessment of coatings performance results
obtained after 6 weeks of accelerated weathering.
95
WOOD IS GOOD
2. MATERIALS AND METHODS
In this study samples of spruce wood (Picea abies L.) free from defects, for the most part of
radial texture was used. Four replicate samples of 150x74x18 mm per coating system were
prepared in accordance with HRN EN 927-6 for accelerated exposure. Three panels were used
for exposure and fourth was unexposed reference. Two replicate samples of 150x70x20 mm
per coating system were prepared in accordance with HRN EN 927-4 for water vapour
absorption test, and two replicate samples in accordance with HRN EN 927-5 for liquid water
absorption test. Coating systems that were tested in this study are used for stable constructions
such as windows. Coatings were applied by brush according to manufacture’s instructions.
Semi-transparent coating systems AQS and RS had pigment in primer coat, and BS coating
system in top coat. Description of the coating systems used is presented in Table 1. Coatings
used for the trial were acrylic waterborne dispersion formulated as semi-transparent (AQS,
RS, BS) or white opaque stains (AQO, RO, JO).
Table 1. Marks and description of coating systems
Coating system
Primer coat
(Impregnation)
Spreading
Number
rate
of coats
2
(g/m )
125
1
80
1
140
1
125
1
80
1
80
1
-
Mark
AQS
RS
BS
AQO
RO
JO
ICP
Intermediate coat
Spreading
rate
(g/m2)
80
-
Number
of coats
1
-
Price tag
Number
of coats
Dry film
thickness
of coating
system
(µm)
3
2
2
3
2
2
3
132
53
46
73
91
66
55
Low
High
Medium
Low
High
Medium
Reference
Top coat
Spreading
rate
(g/m2)
125
90
60
125
180
70
50
Reference coating (Internal Comparison Product, ICP) is a standardized product for
comparison whose composition is specified in annex A of HRN EN 927-3. The ICP is a
medium-build, semi-transparent, semi-gloss system based on solvent-borne alkyd technology
and in accordance with the procedure described in HRN EN 927-6 ICP must be applied by
brushing in three coats with dry film thickness of (50±10) µm. Durability of so applied system
in exterior conditions is about 2 years. ICP was produced by Helios factory and it was applied
to all sides of four panels and served as a reference coating.
The coated samples were exposed for 6 weeks to UV-light, water condensation and water
spray in an apparatus with fluorescent lamps (QUV weathering tester). The exposure cycle
consisted of 24 hours of condensation followed by a sub-cycle of 2.5 hours of UVA-340 nm
and 0.5 hours of water spray as given in Table 2.
Table 2. Exposure cycles
96
Step
1
2
Function
Temperature
Condensation (45±3) °C
Sub
cycle
step 3+4
3
4
UV
Spray
(60±3) °C
Duration
24 h
48 x
Cycles of 3 h
consisting of steps
3 and 4
2,5 h
0,5 h
Condition
0.77 W/(m2nm) at 340 nm
6 l/min to 7 l/min., UV off
WOOD IS GOOD
Before exposure initial measurements of colour, gloss and adhesion were performed.
After each cycle of exposure (168 hours) the colour changes was measured and at the end of
the 6 weeks exposure period the panels were assessed for cracking (in accordance with ISO
4628-4), gloss, colour and adhesion.
The measurement of colour change was made with a portable spectrophotometer
Microflash 100d produced by Datacolor (d/8° measuring geometry, 10° standard observer,
D65 standard illuminate, xenon flash lamp source) always on the same 6 marked locations on
sample. The overall colour change (∆E*) was calculated according to the CIE L*a*b* colour
measuring system where, L* describes brightness, a* and b* describe chromatic coordinates
on the red-green and yellow-blue axis. ∆E* is the colour difference between the initial colour
of the sample and the colour of the sample after exposure and it was calculated using the
following formula:
∆E* = [(∆L*)2 + (∆a*)2 + (∆b*)2]1/2
(1)
where ∆L* describes the difference in brightness (+ light, - dark), ∆a* and ∆b* describes
differences in chromaticity coordinates (∆a*: + redder, - greener; ∆b*: + yellower, - bluer).
The gloss was measured using portable glossmeter KSJ with 60° measuring geometry on
the three locations on sample.
The measurement of adhesion was made with cross-cut test according to standard HRN
EN ISO 2409. On each sample four measurements were obtained.
Assessment of the liquid water and water-vapour absorption was carried out according to
standard HRN EN 927-5 and HRN EN 927-4.
Colour change (∆E*) of wood samples during QUV exposure is presented in Figures 1.
All the materials exhibit some initial colour changes during the first week of exposure. The
highest initial colour change has uncoated samples (∆E*=19.2) and the lowest opaque coating
systems. The colour change of uncoated samples has a different trend during exposure than
coated samples, because uncoated samples intensively darken after first week of exposure and
then become lighter. During the exposure colour change of semi-transparent coating systems
increases during exposure while the colour change of opaque coating systems and ICP coating
remain relatively constant during exposure. The colour change of semi-transparent coating
systems is higher than colour change of ICP coating, and colour change of opaque coating
systems is lower than colour change of ICP coating. After 6 week of exposure the highest
colour change is measured on RS coating systems and is 5 times higher than on ICP coating.
Colour change is not in correlation with dry film thickness of semi-transparent coating
systems, because AQS coating system has the highest and BS coating system has the lowest
dry film thickness and both of these systems have the same colour change. As was expected
semi-transparent coating systems changed colour more than opaque coating systems. After 6
week of exposure the highest colour changes was obtained for semi-transparent coating
system RS, and the lowest for opaque coatings system AQO (Table 3).
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WOOD IS GOOD
20
K
ICP
AQS
BS
b
20
K
ICP
AQO
JO
RO
RS
15
Colour change, E*
Colour change, E*
a
10
5
15
10
5
0
0
168
336
504
672
840
168
1008
336
504
672
840
1008
Time of exposure (hours)
Time of exposure (hours)
Figure 1. Colour changes of uncoated and coated samples during accelerated exposure
Applying of semi-transparent coating system RS and opaque coating systems RO and JO
was a bit more difficult than applying of other coatings systems due to higher viscosity. In
Table 3 can be seen that coating systems with higher initial gloss changed gloss more after 6
weeks of exposure. Initial adhesion of all coatings systems was evaluated with grade 2,
exceptions were coating system BS with grade 3, and coating system AQO with grade 1.
Coating systems AQS-B, RO and JO did not changed adhesion after 6 weeks of exposure,
while adhesion of other coating systems reduced for one grade. After 6 weeks of exposure
crack on unfinished samples was the largest and visible with the naked eye. On finished
samples, only on samples coated with RS coating system appeared cracks visible with
magnification (10x). It could be due to the brittleness of intermediate coat (GRAYSTONE,
1985). The most pronounced changes on the surface of samples after 6 weeks of accelerated
exposure were colour and gloss changes, and base on these changes the rating of general
appearance of samples was made.
Table 3. Results of coating systems testing after accelerate exposure
Initial ratings
Sample
mark
K
AQS
RS
BS
AQO
RO
JO
ICP
After 6 weeks of exposure
Ease of
app.
Gloss
Adhesion*
Colour
change
(∆E)
Excellent
Good
Excellent
Excellent
Good
Good
Excellent
4.5
60.4
22
23.7
64.9
24.8
49.5
71.1
2
2
3
1
2
2
2
8.8
6.8
12.2
6.6
1.3
2.1
2
2
Gloss
2.7
26.8
6.6
6
12.1
18.6
9.2
2.3
Numerical
Adhesion* cracking
ratings*
2
3
4
2
2
2
3
4
0
1
0
0
0
0
0
General
appearance
according to
EN 927-6,
table3*
5
3
3
2
1
2
1
3
* 0 unchanged, 5 sever, i.e. intense change
The results of the liquid water absorption test show that wood samples finished with
coatings systems absorbed less water than unfinished samples (Figure 2a). It can also be seen
98
WOOD IS GOOD
that liquid water absorption of two semi-transparent coating systems (AQS and RS) is lower
than opaque coating systems. Lower liquid water absorption of AQS coating system can be
due to the highest dry film thickness, and lower liquid water absorption of RS coating system
can be due to adding intermediate coat in coating system. Among all tested coating systems
two semi-transparent (AQS-B and RS) and only one opaque coating system (RO) and ICP
coating exhibit the value of liquid water permeability lower than 175 g/m2 which is according
to HRN EN 927-2 limit value for coatings intended to use for dimensionally stable wood
products such as windows and doors (Figure 2a). According to EKSTEDT – ÖSTBERG
(2001) the proposed performance specifications in EN 927 - 2 for the water absorption values
for coatings to be used in different constructions seem to be set at acceptable levels. There is
good correlation between the level of water absorption and practical experience of the
performance of the paints in Scandinavia.
Water vapour absorption of BS, AQO and JO coating systems shows smaller deviations
in values of unfinished and finished wood surfaces (Figure 2b) which means that the these
coating systems less protect wooden substrate from water-vapour absorption and liquid water
uptake in the exposures to the high humidity for longer intervals (e.g. in autumn and winter
months).
On the basis of the results we cannot establish absolute durability of the tested coating
systems, but it is possible to compare their performances with reference coating and with each
other. The best performance of semi-transparent coatings in terms of colour retention,
adhesion and liquid water absorption showed AQS coating system which was the cheapest of
the tested semi-transparent coating systems. It has been established that opaque coating
systems are hard to ranking after 6 weeks of accelerated exposure. Only RO coating system
with highest price meet required performance of water absorption value for dimensional
stable wood products.
Figure 2. Liquid water and water vapour absorption of uncoated and coated samples
99
WOOD IS GOOD
4. CONCLUSION
On the basis of the results we cannot establish absolute durability of tested products, but
we can make comparison to the reference coating of known composition (ICP). The problem
is that ICP specified in standard HRN EN 927-6 is solvent-borne but most wood coatings are
nowadays water-borne. Therefore in the future the new waterborne ICP should be integrated
into the standard.
Based on results of water absorption we can conclude that only opaque coating system
with high price tag exhibited accepted water absorption value for ”stable constructions”.
Semi-transparent coating system with medium price tag did not meet required performance
for water absorption.
It has been established that exposure period of 6 weeks is too short to predict performance
of opaque coatings.
Based on the overall performance results we can conclude that low price tag of the semitransparent coating systems does not mean poorer performance. On the contrary, the cheapest
coating system performed best after 6 weeks of accelerated exposure.
The artificial weathering could be used for ranking of coating systems performance, but
only natural weathering in field tests will gain information about outdoor performance and
lifetime expectancy.
5. REFERENCES
DE WINDT, I.; COPPENS, H.; VAN ACKER, J. (2006): Performance assessment of coating systems for
exterior wooden joinery. Technological attraction poles, Final report PA-04, project co-ordination
H. Coppens, Centre Technique de l’Industrie du Bois, Technisch Centrum der Houtnikverheid,
Brussels.
EKSTEDT, J.; ÖSTBERG, G. (2001): Liquid water permeability of exterior wood coatings-testing
according to a proposed European standard method. Journal of Coatings Technology 73 (914):
pp. 53-59.
GRAYSTONE, J. (1985): The care and protection of wood. ICI Paints Division, Slough.
KNEABE, M. (1995): Paint, stain, varnish, or preservative? It’s your choice. A Forest Products
Laboratory finishing factsheet
URL: http://www.fpl.fs.fed.us/documnts/finlines/knaeb95b.pdf, 10.6.2013.
JIROUŠ-RAJKOVIĆ, V.; TURKULIN, H.; BORIĆ, D.; PETROVIĆ, M. (2005): Durability of exterior wood
coatings. In Proceedings of the 7th International conference on wood technology, construction
industry and wood protection under motto “Durability and quality of structural wood products”.
Croatia, Zagreb. April, 2005. pp. 63-69.
MIKLEČIĆ, J.; JIROUŠ-RAJKOVIĆ, V. (2011): Accelerated weathering of coated and uncoated beech
wood modified with citric acid. Drvna Industrija 62 (4): pp. 277-282.
100
WOOD IS GOOD
Numerical Analysis of Laminated Wood Structures - Chairs by Application
of FEA
NESTOROVIĆ Biserkaa*– GRBAC Ivicab – NESTOROVIĆ Predragc
a
University of Belgrade Faculty of Forestry, Belgrade Serbia
University of Zagreb Faculty of Forestry, Zagreb, Croatia
c
University of Belgrade Faculty of Architecture, Belgrade, Serbia
*
b
Abstract – Models of the chair structure of laminated wood are presented in this paper for the cases of
suspension on four and two legs - cantilever chair. All numerical analysis are done by application of
quadrilateral finite plate and shell element for the case of composite. Modeling of the edge supports of
cantilever chair, which basically represents a beam laminated element, is done by composite plate
element in software package KOMIPS. However, the obtained results are very reliable considering
that sufficiently dense mesh was adopted, which problem of the beam subjected to the banding in its
plane reduces to the analysis of set of small plate elements.
FEA / laminated wood / chairs
1. INTRODUCTION
1.1. Wood laminated specimens
Obtained numerical results by application of software package REDKRUT and
experimental analysis of wood laminated specimens E 2.1.1 and E 2.2.1 are shown in the
Figure 1 and Figure 2. It could be noticed that they show a very good compliance with the
experimental values. Composite t = 8 x 1,5 = 12.0 mm, 0/0/0/0 / 0/0/0/0 (lamina orientation in
specimen)
Specimen dimensions are 30x250 mm.
ΣF = 10000 N
fmax = 0,21 mm , σmaxekv = 27,8 Mpa
Figure 1. Computer simulation of the experimental analysis of wooden specimen E 2.1.1
Composite t = 8 x 1,5 = 12.0 mm, 90/90/90/90 / 90/90/90/90 (lamina orientation in specimen)
Specimen dimensions are 30x250 mm
ΣF = 1000 N
fmax= 0,167mm , σmaxekv = 2,78 Mpa
Figure 2. Computer simulation of the experimental analysis of wooden specimen E 2.1.2
101
WOOD IS GOOD
2. WOOD LAMINATED CHAIR STRUCTURE
Models of chair structure made of laminated wood are shown in the Figure 3 for the case
of the rest on four legs and Figure 6 for the rest on two legs (cantilever chair).
2.1. Model of the chair rested on the four legs
Material characteristics of lamina are given in the following tables and the results of the
stress and strain analysis are shown in the Figure 4 for the case of vertical and in the Figure 5
for the case of vertical and horizontal load.
Figure 3. Layout of the chair rested on four legs
Composite: t1 = 17x1,2 = 20,4 mm , 0/0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0/0 - longitudinal and
transversal beams.
Table 1. Elasticity matrix for massive lamina
ELASTICITY MATRIX FOR MASSIVE - LAMINA Q[MPa]
1,1
1,2
1,6
2,2
2,6
6,6
QD(i,j) 1.76E+04 9.730E+02 0.000E+00 2.14E+03 0.000E+00 1.15E+03
Composite t = 8 x 1,2 = 9,6 mm 0/90/0/90 / 90/0/90/0 (lamina orientation in specimen)
Table 2. Material properties
LAYER PROPERTIES
H1
H2
E11/Q11 E22/Q12 Ni12/Q16
0/Q22
0/Q26 G12/Q66
Teta
4.8
3.6 1.76E+04 9.73E+02 0.00E+00 2.14E+03 0.00E+00 1.15E+03 0.00E+00
3.6
2.4 2.14E+03 9.73E+02 0.00E+00 1.76E+04 0.00E+00 1.15E+03 9.00E+01
2.4
1.2 1.76E+04 9.73E+02 0.00E+00 2.14E+03 0.00E+00 1.15E+03 0.00E+00
1.2
.0 2.14E+03 9.73E+02 0.00E+00 1.76E+04 0.00E+00 1.15E+03 9.00E+01
.0 -1.2 2.14E+03 9.73E+02 0.00E+00 1.76E+04 0.00E+00 1.15E+03 9.00E+01
-1.2 -2.4 1.76E+04 9.73E+02 0.00E+00 2.14E+03 0.00E+00 1.15E+03 0.00E+00
-2.4 -3.6 2.14E+03 9.73E+02 0.00E+00 1.76E+04 0.00E+00 1.15E+03 9.00E+01
-3.6 -4.8 1.76E+04 9.73E+02 0.00E+00 2.14E+03 0.00E+00 1.15E+03 0.00E+00
REDUCED STIFFNESS OF LAMINATE
1,1
1,2
1,6
2,2
2,6
6,6
A(i,j) 9.5270E+04 9.3408E+03 0.0000E+00 9.5270E+04 0.0000E+00 1.0032E+04
B(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
D(i,j) 9.4540E+05 7.1737E+04 0.0000E+00 5.1796E+05 0.0000E+00 7.7046E+04
LAMINATA REDUCED ELASTICITY MATRIX OF LAMINATE
1,1
1,2
1,6
2,2
2,6
6,6
QA(i,j) 9.9240E+03 9.7300E+02 0.0000E+00 9.9240E+03 0.0000E+00 1.150E+03
QB(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
QD(i,j) 1.2823E+04 9.7300E+02 0.0000E+00 7.0252E+03 0.0000E+00 1.150E+03
102
WOOD IS GOOD
Figure 4. Reduced stiffness – the first load case
For the first load case stress concentration is maximal in the central area of the seat and is
5,18 MPa, compared to the maximal fracture stress obtained experimentally for banding of
89,95 MPa.
Figure 5. Reduced stiffness – the second load case
In the second load case maximal stress is 16 MPa, and is in the curved part of transition
between back and seat, however its values are far below the boundary fracture stress σfx.
2.2. Model of the chair rested on two legs (cantilever chair)
Three load cases were analyzed: horizontal load on the chair back with and without seat,
and load by vertical force on the chair seat.
The chair rested on two legs Figure 6 subjected to bending by the action of horizontal
concentrated force of 100 N at the top of the back is analyzed for the case of the entire
structure, with the elements of plate for seat and backrest as well as for the case without these
elements. The results of the analysis of the first load case include both real and reduced
stiffness of the laminate are shown in the Figure 7.
Figure 6. Layout of the chair rested on two legs - cantilever chair and the way of load
103
WOOD IS GOOD
Composite : t1 = 23x1,2 = 27,6 mm , 0/0/0/0/0/0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0/0/0/0/0/0 longitudinal beams
Composite: t2 = 15x1,2 = 18 mm , 0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0 - transverse beams
ELASTICITY MATRIX FOR MASSIVE - LAMINE Q[MPa]
1,1
1,2
1,6
2,2
2,6
6,6
QD(i,j) 1.76E+04 9.730E+02 0.000E+00 2.14E+03 0.000E+00 1.145E+03
Composite: t3 = 12 x 1,2 = 14,4 mm, 0/90/0/90/0/90 / 90/0/90/0/90/0 (lamina orientation)
LAYER PROPERTIES
H1
H2
E11/Q11
7.2
6.0 1.76E+04
6.0
4.8 2.14E+03
4.8
3.6 1.76E+04
3.6
2.4 2.14E+03
2.4
1.2 1.76E+04
1.2
.0 2.14E+03
.0 -1.2 2.14E+03
-1.2 -2.4 1.76E+04
-2.4 -3.6 2.14E+03
-3.6 -4.8 1.76E+04
-4.8 -6.0 2.14E+03
-6.0 -7.2 1.76E+04
E22/Q12
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
Ni12/Q16
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0/Q22
2.14E+03
1.76E+04
2.14E+03
1.76E+04
2.14E+03
1.76E+04
1.76E+04
2.14E+03
1.76E+04
2.14E+03
1.76E+04
2.14E+03
0/Q26
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
1,1
1,2
1,6
2,2
A(i,j) 1.4291E+05 1.4011E+04 0.0000E+00 1.4291E+05
B(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
D(i,j) 2.9503E+06 2.4211E+05 0.0000E+00 1.9885E+06
LAMINATA REDUCED ELASTICITY MATRIX OF LAMINATE
1,1
1,2
1,6
2,2
QA(i,j) 9.9240E+03 9.7300E+02 0.0000E+00 9.9240E+03
QB(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
QD(i,j) 1.1856E+04 9.7300E+02 0.0000E+00 7.9915E+03
Composite: t4 = 8x1,2 = 9,6 mm
G12/Q66
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
Teta
0.00E+00
9.00E+01
0.00E+00
9.00E+01
0.00E+00
9.00E+01
9.00E+01
0.00E+00
9.00E+01
0.00E+00
9.00E+01
0.00E+00
2,6
6,6
0.0000E+00 1.5048E+04
0.0000E+00 0.0000E+00
0.0000E+00 2.6003E+05
2,6
6,6
0.0000E+00 1.0450E+03
0.0000E+00 0.0000E+00
0.0000E+00 1.0450E+03
0/90/0/90 / 90/0/90/0
LAYER PROPERTIES
H1
H2
E11/Q11
4.8
3.6 1.76E+04
3.6
2.4 2.14E+03
2.4
1.2 1.76E+04
1.2
.0 2.14E+03
.0 -1.2 2.14E+03
-1.2 -2.4 1.76E+04
-2.4 -3.6 2.14E+03
-3.6 -4.8 1.76E+04
E22/Q12
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
Ni12/Q16
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0/Q22
2.14E+03
1.76E+04
2.14E+03
1.76E+04
1.76E+04
2.14E+03
1.76E+04
2.14E+03
0/Q26
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
G12/Q66
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
Teta
0.00E+00
9.00E+01
0.00E+00
9.00E+01
9.00E+01
0.00E+00
9.00E+01
0.00E+00
1,1
1,2
1,6
2,2
2,6
6,6
A(i,j) 9.5270E+04 9.3408E+03 0.0000E+00 9.5270E+04 0.0000E+00 1.0032E+04
B(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
D(i,j) 9.4540E+05 7.1737E+04 0.0000E+00 5.1796E+05 0.0000E+00 7.7046E+04
REDUCED ELASTICITY
1,1
QA(i,j) 9.9240E+03
QB(i,j) 0.0000E+00
QD(i,j) 1.2823E+04
104
MATRIX OF LAMINATE
1,2
1,6
2,2
2,6
6,6
9.7300E+02 0.0000E+00 9.9240E+03 0.0000E+00 1.150E+03
0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
9.7300E+02 0.0000E+00 7.0252E+03 0.0000E+00 1.150E+03
WOOD IS GOOD
Figure 7. Reduced stiffness - first load case
The critical load is in the lower arched part of the chair leg of 6,79 MPa compared to the
fracture stress which is σfx = 134,78 MPa, multiply over dimensioned.
In Figure 8 is given the model of the edge girders. Load and strain state is given in
Figure 9, and stress cahnge is given in the Figure 10.
Figure 8. Model of edge supports of the chair second load case
Composite: t1 = 23x1,2 = 27,6 mm , 0/0/0/0/0/0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0/0/0/0/0/0 longitudinal beams.
Composite: t2 = 15x1,2 = 18 mm , 0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0 - transverse beams.
1,1
1,2
1,6
2,2
2,6
6,6
QD(i,j) 1.76E+04 9.730E+02 0.000E+00 2.14E+03 0.000E+00 1.15E+03
Figure 9. Load and strain model of the chair with edge girders; Figure 10. Stress state of the chair
with edge girders
105
WOOD IS GOOD
Chair loaded in the same way as the previous one without seat plate, shows a high
concentration of the stress in the part of the seat on the composition of horizontal beams and
legs, visually observed as dense disposition of isocurves of equivalent stress, which should be
avoided, although the maximum stress values are hear small.
The third model of the chair with edge girders and plates with continuous-loaded seat
(replaced by concentrated forces) is shown in Figure 11. Numerical computation by finite
elements is verified via deflection experimentally. Laser deflection meter is placed in the
middle of the span, below the lower binder which connects chair legs.
Figure 11. Layout of cantilever chair for the third load case
In the experiment, on the seat of the chair the weight of mass ΣF=700 N was placed. The
finite element mesh of this model with the numbers of nodal points and the numbers of finite
plate elements is shown in the Figure 12 and Figure 13. and pointed stress and strain images
Figure 14 and Figure 15.
Figure 12. Labeling of the nodes by finite elements; Figure 13. Labeling of surfaces by finite elements
The calculation was prepared and completed as follows:
Laminate: t1 = 23x1,2 = 27,6 mm , 0/0/0/0/0/0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0/0/0/0/0/0 longitudinal beams.
Laminate: t2 = 15x1,2 = 18 mm , 0/0/0/0/0/0/0 /0/ 0/0/0/0/0/0/0 - transverse beams.
1,1
1,2
1,6
2,2
2,6
6,6
QD(i,j) 1.76E+04 9.730E+02 0.000E+00 2.14E+03 0.000E+00 1.15E+03
Laminate: t3 = 12x1,2 = 14,4 mm
106
0/90/0/90/0/90 / 90/0/90/0/90/0 - backrest.
WOOD IS GOOD
LAYER PROPERTIES
H1
7.2
6.0
4.8
3.6
2.4
1.2
.0
-1.2
-2.4
-3.6
-4.8
-6.0
H2
6.0
4.8
3.6
2.4
1.2
.0
-1.2
-2.4
-3.6
-4.8
-6.0
-7.2
E11/Q11
1.76E+04
2.14E+03
1.76E+04
2.14E+03
1.76E+04
2.14E+03
2.14E+03
1.76E+04
2.14E+03
1.76E+04
2.14E+03
1.76E+04
E22/Q12
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
Ni12/Q16
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0/Q22
2.14E+03
1.76E+04
2.14E+03
1.76E+04
2.14E+03
1.76E+04
1.76E+04
2.14E+03
1.76E+04
2.14E+03
1.76E+04
2.14E+03
0/Q26
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
G12/Q66
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
Teta
0.00E+00
9.00E+01
0.00E+00
9.00E+01
0.00E+00
9.00E+01
9.00E+01
0.00E+00
9.00E+01
0.00E+00
9.00E+01
0.00E+00
A(i,j)
B(i,j)
D(i,j)
1,1
1,2
1,6
2,2
2,6
6,6
1.4291E+05 1.4011E+04 0.0000E+00 1.4291E+05 0.0000E+00 1.5048E+04
0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
2.9503E+06 2.4211E+05 0.0000E+00 1.9885E+06 0.0000E+00 2.6003E+05
REDUCED ELASTICITY MATRIX OF LAMINATE
1,1
1,2
1,6
2,2
2,6
6,6
QA(i,j) 9.9240E+03 9.7300E+02 0.0000E+00 9.9240E+03 0.0000E+00 1.0450E+03
QB(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
QD(i,j) 1.1856E+04 9.7300E+02 0.0000E+00 7.9915E+03 0.0000E+00 1.0450E+03
Laminate: t4 = 8x1,2 = 9,6 mm
0/90/0/90 / 90/0/90/0 - seat
LAYER PROPERTIES
H1
4.8
3.6
2.4
1.2
.0
-1.2
-2.4
-3.6
H2
3.6
2.4
1.2
.0
-1.2
-2.4
-3.6
-4.8
E11/Q11
1.76E+04
2.14E+03
1.76E+04
2.14E+03
2.14E+03
1.76E+04
2.14E+03
1.76E+04
E22/Q12
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
9.73E+02
Ni12/Q16
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0/Q22
2.14E+03
1.76E+04
2.14E+03
1.76E+04
1.76E+04
2.14E+03
1.76E+04
2.14E+03
0/Q26
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00
G12/Q66
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
1.15E+03
Teta
0.00E+00
9.00E+01
0.00E+00
9.00E+01
9.00E+01
0.00E+00
9.00E+01
0.00E+00
A(i,j)
B(i,j)
D(i,j)
1,1
1,2
1,6
2,2
2,6
6,6
9.5270E+04 9.3408E+03 0.0000E+00 9.5270E+04 0.0000E+00 1.0032E+04
0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
9.4540E+05 7.1737E+04 0.0000E+00 5.1796E+05 0.0000E+00 7.7046E+04
REDUCED ELASTICITY MATRIX OF LAMINATE
1,1
1,2
1,6
2,2
2,6
6,6
QA(i,j) 9.9240E+03 9.7300E+02 0.0000E+00 9.9240E+03 0.0000E+00 1.150E+03
QB(i,j) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
QD(i,j) 1.2823E+04 9.7300E+02 0.0000E+00 7.0252E+03 0.0000E+00 1.150E+03
Figure 14. Strain for the third load case;
Figure 15. Reduced stiffness third load case
107
WOOD IS GOOD
The maximal deflection of 43,2 mm refers to the backrest of the chair. Deflection
obtained numerically above the laser meter was 12,5 mm. Experimental average deflection
values were measured for 5 chairs, and were as follows: 11,5; 11,6; 11,4; 11,5 and 11,6 mm.
It can be concluded that experimental measurements confirmed the numerical calculation.
Layout of the model of cantilevered chair was given in the Figure 6. The pneumatically load
of the chair seat is given in the Figure 16, the initial measurement of deflection of the relieved
cantilever chair by laser meter was given in the Figure 17, the measurement of deflection by
laser meter under vertical load of chair seat was given in the Figure 18, determination of the
horizontal force on the backrest of the chair by dynamometer is given in the Figure 19. The
maximum stress is also on the lower and upper part of the arch of the chair leg and is 9,85
MPa.
Figure 16. Pneumatically load on
the seat of cantilever chair
Figure 17. Relieved cantilever chair with
measurement of deflection by laser meter
Figure 18. Measurement of deflection by
laser meter under vertical load on the seat
of cantilever chair by weight of 700 N
Figure 19. Determination of the
horizontal force on the backrest of the
chair by dynamometer
The obtained numerical results for the case of geometrically free-form shell (seat with
beck) and the entire structure with the elements of the plates for seat and back rested on two
legs has been confirmed experimentally on the real cantilever chair, and deflection was fmax =
12,5 mm.
3. CONCLUSION
Conducted research within the framework of theoretical, experimental and numerical part
and introduction of reduced stiffness of complex laminate in finite elements, along with
experiments with chairs, which were done with the objective of determination of stiffness of
such systems by measurement of real displacements on selected models, confirm numerical
calculation. Previously enables design, redesign, construction and dimensioning not of only
108
WOOD IS GOOD
chairs but any beam or surface system on the base of laminate, with the posibility of material
variation, combination of different materials, leyet thickness and fiber orientation.
Acknowledgements: Authors are supported by the Ministry of Education, Science and
Technological Development of the Republic of Serbia, Project No. TP 36008.
4. REFERENCES
NESTOROVIĆ, B. (2010): Istraživanje i analiza čvrstoće nameštaja za sedenje izgrađenog od laminata
na bazi drveta. Doktorska disertacija. Univerzitet u Beogradu, Šumarski fakultet: pp. 101-118.
MANESKI, T. (1998): Kompjutersko modeliranje i proračun struktura. Mašinski fakultet Univerziteta u
Beogradu, br. 8, Beograd.
109
WOOD IS GOOD
The Impact of Wood Staining on the Adhesion of Certain Types of Coating
PALIJA Tanjaa*– VUČKOVIĆ Aleksandara – JEVTIĆ Petronijeb – JAIĆ Milana
a
Technology, Management and Design of Furniture and Wood Products, Faculty of Forestry, University of
Belgrade, Belgrade, Serbia
b
Graduate School of Applied Professional Studies, Vranje, Serbia
*
Abstract – This paper investigates the impact of the staining of spruce wood (Picea Abies Karst.) on
the adhesion of different types of coating. The samples were stained with water-based stain and
lacquered using three types of transparent coatings: nitrocellulose (NC), polyurethane (PU) and waterbased coating (WB). Since the water from the stain leads to swelling of wood tissue and an increase of
roughness in the surface layer, surface roughness of wood was measured before and after staining and
related to the adhesion of coatings. Among unstained samples, the highest values of adhesion (4.50
MPa) was obtained in samples lacquered with WB coating, fallowing by samples lacquered with PU
coating (3.72 MPa) and samples lacquered with NC coating (2.43 MPa). Staining of wood had a
negative impact on the value of adhesion in the case of WB coating (4.11 MPa). The increase in
surface roughness as a result of staining had a positive impact on the value of adhesion for samples
which were lacquered with PU coating (4.87 MPa). The samples which were stained and lacquered
with NC coating showed a slight increase in adhesion value compared to samples lacquered with same
type of coating without staining (2.74 MPa).
spruce wood / staining / surface roughness/ coating / adhesion
1. INTRODUCTION
Stains represent the dispersion of pigments or dyes in an appropriate solvent. Staining
procedure can change the natural colour of the wood while preserving its texture. In order to
protect the wood from the negative effects of environmental factors and to preserve obtained
colour of wood, it is necessary to lacquer wood with transparent coating after staining.
Application of water-based stains is environmentally justified, since working
environment is free from vapours of organic components in to the air. In addition, waterbased stains are non-flammable and non-hazardous (CHARRON, 1998). Application of these
stains gives the vibrant colour tones and uniformity of colour over the surface thanks to the
great depth of water penetration into the substrate. However, the use of water-based stains has
its disadvantages. First, the wood swells in contact with water. After staining, the water
evaporates from the surface of wood causing the wood fibres to raise and bend which leads to
an increase in surface roughness (JAIĆ – ZIVANOVIC-TRBOJEVIĆ, 2000). The increase in
roughness can have a negative impact on the aesthetic quality of lacquered surfaces, as glow
is a function of the surface roughness. In addition, with the increase in the surface roughness
the contact area between the substrate and the coating increases as well. Knowing the
different mechanisms of adhesion of the coating to the wood substrate, the increase in
roughness can have a different impact on the value of adhesion of different types of coating.
Generally, higher values of adhesion between the coating and the substrate are expected if the
surface is roughened before lacquering (WICKS et al., 2007; RIZZO – BRUNO, 2009). On the
other hand, previous studies have shown that the increase in roughness expressed as
parameters Sa1, which occurred as a result of sanding with sanding belts with different grits,
has no significant impact on the adhesion of samples lacquered with water-based coating
(COOL – HERNANDEZ, 2011). In examination of the effect of different treatments of spruce
1
The arithmetical mean deviation of the profile
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wood before lacquering with NC coating on the values of adhesion, no correlation between
the roughness of the surface which is caused by treatment with the stains, bleaching agents
and preservatives and adhesion values was found (OZDEMIR – HIZIROGLU, 2007). Based on
this result it can be concluded that the increase in roughness cannot be considered separately
from the material by which this effect is achieved.
The aim of this paper is to investigate the impact of staining of wood by water-based
stain on the value of the adhesion of the three most commonly used coatings in the wood
industry: nitrocellulose (NC), polyurethane (PU) and water-based (WB) coating. As high
values of other mechanical properties of lacquered surface have little significance if adhesion
between the coating and the substrate is disrupted (RIZZO – BRUNO, 2009), testing of the
adhesion of coating on previously treated wood gets even more importance. Since it is
believed that the optimal method for determination of coating adhesion is combination of
direct adhesion measuring methods and characterization of substrate surface (AWAJI et al.,
2009), geometrical state of wood surface and adhesion measurements were conducted in this
research.
2. MATERIALS AND METHODS
2.1. Choice of substrate
Spruce (Picea Abies Karst.) is known as the wood species of a small density, low
permeability, and high volume porosity (72 % according to ŠOŠKIĆ et al., 2007). During the
drying process pits between transports elements became closed, which leads to decrease in
permeability of wood tissue, which may affect the penetration of the coating into the substrate
(GINDL et al., 2006). Lower depth of penetration of coatings leads to decrease of contact area
between the coating and the substrate, which may affect the value of adhesion (MEIJER et al.,
1998). In addition, the porosity of the wood is considered as one of the significant factors that
affect the value of adhesion (SONMEZ et al., 2009; OZDEMIR – HIZIROGLU, 2007). Previous
studies had shown that compared with higher density wood species, samples of spruce wood
will have lower value of adhesion (JAIĆ – PALIJA, 2012). For this research, 12 samples of
spruce wood with dimensions of 400×100×20 mm were used. Spruce samples were prepared
by sanding on narrow-belt sander with manual pressure control (MiniMax L55) in a threestage grit system: N˚ 80, N˚ 120 and N˚ 180. Sanding speed was 19 m/s. The moisture content
of spruce samples was measured by hydrometer (NIGOS DVD-240). For each sample
moisture content was measured at two positions. After sanding, one-half of all samples was
stained by applying water-based stain (025 AC Colorata VERINLEGNO) by air-spraying in a
chamber with controlled conditions of the working environment (t = 20±2 °C, φ = 50±5 %).
The spraying pressure was 3.5 bars, and nozzle diameter of spray-gun was 1.8 mm. To
examine the effect of staining on the adhesion of different types of coating one-third of all
samples was lacquered with 1K NC coating (NF VERINLEGNO 50), second-third with 2K
PU coating (VF A TX 2019 E VERINLEGNO) and the last-third with 1K water-based
coating (200 IDROFOND TX INT VERINLEGNO). All of coatings were transparent. The
scheme of surface finishing treatment by groups of samples is given in the Table 1.
Table 1. Scheme of the surface finishing treatment of samples by groups
Treatment
Water-based stain
NC coating
PU coating
WB coating
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1
*
Serial number of the sample group
2
3
4
5
*
*
*
*
*
*
6
*
*
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All coatings were applied to the surface of control (non-stained) and stained samples by
air-spraying process in a single coat in the same working environment conditions as for
staining. Spraying pressure was 3.5 bar, and the distance between spay-gun and sample 20
cm. The nozzle diameter of spray gun for NC, PU and WB coatings were: 1.8 mm, 1.8 mm
and 2.2 mm, respectively. Technical characteristics of applied stain and coatings are given in
Table 2.
Table 2. Technical characteristics of the water-based stain and NC, PU and WB coating
WB coating
Material
NC coating
PU coating
Water-based stain
Density (kg/m3)
0,980±1 %
0,950±1 %
0,970±1 %
1,020±1 %
Added diluents (%)
20-30
20-40
0-10
Viscosity (20 °C)
12 ±1 s (DIN 4)
15-20 s (DIN 4) 14-16 s (DIN 4) 30-50 s (DIN6)
Solid content (%)
11±1 %
21-23
38-42
32-34
50-80
120-180
120-150
120-150
Application rate (g/m2)
2.2. Determination of the geometric state of wood surface
The characterization of the substrate before and after staining was performed by
determining roughness parameter Ra by contact-mechanical roughness tester (TR200,
manufacturer Beijing TIME High Technology Ltd.), in accordance with ISO 4288: 1996.
Determination of roughness parameters is based on the movement of 2 µm-radius diamond tip
stylus at 90˚ angle to the surface of the wood. During the movement the force of 4 mN
ensures constant contact of the stylus tip and on the surface of the sample. Vertical movement
of the stylus tip is transformed into an electrical signal that is filtered and translated into the
value of parameter Ra. The parameter Ra was measured in the transverse and longitudinal
direction relative to the direction of wood fibres (Figure 1). For each group of samples 9
measurements were performed, and the result is presented as the mean value of measurements
in transverse and longitudinal direction.
Figure 1. Determination of the parameter Ra after sanding parallel to the wood fibres
2.3. Determination of the dry film thickness of the coating
Dry film thickness of the coating was determined by modern non-destructive method
using an ultrasound gauge (POSITector 200, DeFelsko), in accordance with EN ISO 2808:
2011. The principle of determining the thickness of the coating is based on the measurement
of time needed for ultrasonic waves, emitted from the surface of the probe, to pass through the
coating to the surface of substrate and same path back to the transducer. Knowing that there is
unevenness on the surface of the coating that can cause the errors in the reading, drop of gel
(water-glycerine-based) was placed on the coating, filling the irregularities on the surface of
the coating. Thickness of the coating was obtained as the mean value of 8 measurements for
each group.
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Figure 2. Measurement of the dry film thickness of the coating
2.4. Determination of the adhesion of coating
2.4.1. Determination of adhesion of coating by cross-cut test
Determination of the adhesion of coatings by cross-cut test (by Paint Inspection
Gauge121/4, manufacturer Elcometer) was conducted in accordance with EN ISO 2409:
2010.The principle of determination of the adhesion is based on the evaluation of the
resistance of the coating to the indentation. Firstly, six parallel cuts were made at lacquered
surface at 45˚ angle relative to the direction of wood fibres. Afterwards, the six more cuts
were formed at 90˚ angle to the first cut, forming lattice pattern on the coating. Evaluation of
the coating adhesion was made by appearance of the lattice. Lowest evaluation mark (0)
means that the edges of the cuts are completely smooth; while the highest mark (5) means that
the lattice is severely damaged. The blades are set at a distance of 3 mm, which is consistent
with the measured dry film thickness of coatings. To obtain valid results, it is necessary for
the blades to penetrate to the surface of the substrate. By applying the ink on surface of
formed lattice, the depth of blade penetration was determined (Discoloration of wood beneath
the lattice lines is the proof of the blade penetrating the surface of the substrate). The total
number of adhesion measurements was18 (three measurements for each group of samples). In
Figure 3 cross-cut test instrument is shown.
Figure 3. Determination of adhesion of coating by cross-cut test
2.4.2. Determination of the adhesion of coating by pull-off test
Determination of the adhesion of the coating by pull-off test was performed according to
the EN ISO 4624: 2005 (using PosiTest AT-A instrument, manufacturer DeFelsko). Pull-off
test is destructive method for determining tensile strength of wood coatings. Tensile strength
is calculated as the ratio of pulling force that leads to the detachment of the coating from the
surface of the wood and the surface to which the pulling force is applied. The instrument
consists of a housing containing the hydraulic pump and the actuator, which is connected to
the housing by cable. The pulling force was applied to coating via 20-mm diameter
aluminium dollies that were glued to the lacquered surface with 2K epoxy adhesive
(ARALDITE 2001, Huntsman). The measuring principle involves cleaning the surface of dollies
to provide a clean and flat surface, i.e. to remove impurities from the surface that may have an
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impact on the value of adhesion, and gluing of cleaned dollies to the lacquered surface. After
curing of adhesive (24 hours), the pulling force was measured. In order to obtain accurate
data, area under dollies was separated from the rest of the lacquered surface by circular
groove, which is formed by a cylindrical cutting tool. This way, the pulling force was limited
solely on the coating underneath the dollies. The total number of measurements was 60 (10
measurements for each group of samples). Figure 2 shows the equipment for measurement of
the adhesion by pull-off test.
Figure 4. Measurement of adhesion of coating by pull-off test
3. Results and Discussion
The average moisture content of spruce samples before staining and lacquering was
9.04 %. The average surface roughness after sanding of the samples expressed as parameter
Ra perpendicular to the wood fibres was 3,426 µm and 2,552 µm parallel to the wood fibres.
The small difference in the value of the parameter Ra perpendicular and parallel to the wood
fibres can be explained by the high value of the reference length. Both early and late wood
were included in observing length, so the surface roughness parallel to the wood fibres could
not be measured precisely.
Staining of spruce wood with water-based stain led to an increase in surface roughness
for 33.65 % perpendicular and 40.92 % parallel to wood fibres
In Figure 5 increase of roughness of wood after staining perpendicular (a, c, e) and
parallel (b, d, and f) to the direction of the wood fibres is shown graphically.
a)
after staining
before staining
5
4,5
4
3,5
3
Surface roughness
[µm]
Surface roughness
[µm]
before staining
1 2 3 4 5 6 7 8 9
Number of measurement
after staining
4,5
3,5
2,5
1,5
1 2 3 4 5 6 7 8
b)
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5,5
Surface roughness
[µm]
Surface roughness
[µm]
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4,5
3,5
2,5
1 2 3 4 5 6 7 8 9
4,5
3,5
2,5
1,5
1 2 3 4 5 6 7 8 9
d)
6
5,5
5
4,5
4
3,5
3
Surface roughness
[µm]
Surface roughness
[µm]
c)
4,5
4
3,5
3
2,5
2
1,5
1 2 3 4 5 6 7 8 9
e)
1 2 3 4 5 6 7 8
f)
Figure 5. Surface roughness before and after staining perpendicular to the wood fibres: a) Group 4;
c) Group 5; e) Group 6 and parallel to the wood fibres b) Group 4; d ) Group 5; f) Group 6.
Average dry film thickness of the coating of control and stained samples is given in Table 2.
Table 3. Average dry film thickness of the coating of control and stained samples lacquered with NC,
PU and WB coating
Type of coating
Average dry film thickness (µm)
NC
61,44
PU
74,63
WC
50,44
BNC
61,06
BPU
68,88
BWB
58,63
The mean values of adhesion of control and stained lacquered samples measured by
cross-cut and pull-off test are given in Table 3.
Table 4. Mean values of adhesion of control and stained samples lacquered with NC, PU and WB
coating
Type of test
Cross-cut test
Pull-off test (MPa)
NC
1,67
2,43
PU
1
3,72
Type of coating
WB
BNC
1
2
4,50
2,74
BPU
1
4,87
BWB
2
4,11
Comparing the results of adhesion by cross-cut and pull-off test it can be concluded that it
is necessary to include more than one method in the evaluation of adhesion in order to obtain
realistic view of this property. The lowest adhesion values measured by pull-off test registered
on the samples coated with NC coating, with (2.74 MPa) or without staining (2.43 MPa),
were also rated with lower grade (mark 2) in cross-cut test, in comparison to other samples.
Also, samples that showed the highest tensile strength: BPU (4.87 MPa) and WB (4.50 MPa)
obtained the highest marks for resistance to indentation when cutting the coating in the form
of lattice (Grade 1). In samples that were stained and lacquered with WB coating there were
significant disagreement of the adhesion results measured with cross-cut and pull-off method.
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The values of tensile strength of these samples are slightly lower than the value of adhesion of
BPU and WB samples, which obtained mark 1 in cross-cut test. Also high grade of adhesion
measured in cross-cut test of samples lacquered with PU coating is not consistent with the
significantly lower measured values of tensile strength of the same samples.
The value of adhesion of spruce samples lacquered with NC coating was in accordance
with the results of previous studies of the same type of coating on samples of the same wood
species (2.56 MPa at 8 % moisture content according to Sonmez et al., 2009). In the same
research, the adhesion value of the samples of spruce wood lacquered with 2K PU coating
was higher (4.436 MPa), and for samples lacquered with WB coating was lower (3.373 MPa)
compared with the value of adhesion on samples lacquered with these types of coatings in our
research. It should be note that in the above mentioned research the samples were lacquered
by applying two coats of the appropriate type of coating.
The increase in surface roughness of wood by 33 % after staining resulted in increased
adhesion of NC coating by 12.9 %. For samples that were lacquered with PU coating increase
of wood roughness after staining by 39 % led to an increase in the adhesion by 31 %. Only in
the sample lacquered with water-based coating increase of wood roughness after staining by
43.2 % led to reduce of adhesion by 8.7 %. Decease of adhesion of WB coatings after staining
is consistent with the conclusion that the higher values of adhesion of WB coatings can be
achieved when the wood surface is smoother (LANDRY – BLANCHET, 2012).
4. CONCLUSIONS
Based on this research we can conclude the following:
• The formulation of the coating affects the value of the adhesion of coatings on the
wood surface.
• Staining of spruce wood with water-based stain led to an increase in surface
roughness. Staining of wood led to increase of surface roughness which had positive impact
on the value of the adhesion of the samples lacquered with NC and PU coating. For samples
that were lacquered with water-based coating, staining followed by increased surface
roughness had negative impact on adhesion.
ACKNOWLEDGEMENTS: This paper was realized as a part of the project Establishment of Wood
Plantations Intended for the Afforestation of Serbia (31041) financed by the Ministry of Education,
Science and Technological of the Republic of Serbia within the framework Technological
development for the period 2011-2014.
5. REFERENCES
AWAJA, F.; GILBERT, M.; KELLY, G.; FOX, B.; PIGRAM, P. (2009): Adhesion of polymers. Progress in
Polymer Science 34, Elsevier, Amsterdam, pp. 948-968.
CHARRON, A. (1998): Stains and Dyes. In: Water-based finishes, The Taunton Press, pp.67-85.
COOL, J.; HERNANDEZ, R. (2011): Improving the Sanding Process of Black Spruce Wood for Surface
Quality and Water-Based Coating Adhesion. 61 (11): pp. 372–380.
EN ISO 2808 (2007): Paints and varnishes -- Determination of film thickness.
GINDL, M.; SINN, G.; STANZL-TSCHEGG, S. (2006): The effects of ultraviolet light exposure on the
wetting properties of wood. Journal of Adhesion Science and Technology 20 (8): pp. 817-828.
ISO 4288 (1996): Geometrical Product Specifications (GPS) -- Surface texture: Profile method -Rules and procedures for the assessment of surface texture.
JAIĆ, M.; PALIJA, T. (2012): Uticaj vrste drveta i sistema površinske obrade na adheziju premaza.
Zaštita materijala 53 (4): pp. 299-303.
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JAIĆ, M.; ŽIVANOVIĆ-TRBOJEVIĆ, R. (2000): Materijali za površinsku obradu drveta. In: Površinska
obrada drveta, Autorsko izdanje, Beograd, pp.39-90.
LANDRY, V.; BLANCHET, P. (2012): Surface Preparation of Wood for Application of Waterborne
Coatings. Forest products journal 62 (1): pp. 39-45.
MEIJER, M.; THURICH, K.; MILITZ, H. (1998): Comparative study on penetration characteristics of
modern wood coatings. Wood Science and Technology 32: pp.347-365.
OZDEMIR, T.; HIZIROGLU, S. (2007): Evaluation of Surface Quality and Adhesion Strength of Treated
Solid Wood. Journal of Materials Processing Technology 186 (1-3): pp. 311–314.
RIZZO, М.; BRUNO, G. (2009): In: Surface Coatings, Nova Science Publishers Inc., New York, pp.
ŠOŠKIĆ, B.; GOVEDAR, Z.; TODOROVIĆ, N.; PETROVIĆ, D. (2007): Basic physical properties of Spruce
wood (Picea abies Karst.) from plantations. Bulletin of the Faculty of Forestry 96: pp. 97-110.
SRPS EN ISO 2409 (2010): Paints and varnishes -- Cross-cut test.
SRPS EN ISO 4624 (2005): Paints and varnishes -- Pull-off test for adhesion.
WICKS, Z.; JONES, F.; PAPAS, P.; WICKS, D. (2007): Adhesion. In: Organic Coatings: Science and
Technology, Third Edition, Jonh Wiley and Sons, Inc., New Jersey, pp.121-125.
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On Enhancing of Production Planning in Wood Processing and Furniture
Manufacturing
PERIĆ Ivanaa – GRLADINOVIĆ Tomislava*– STARČEVIĆ Igorb – STASIAK-BETLEJEWSKA Renatac
a
Wood Technology Department, Faculty of Forestry, University of Zagreb, Zagreb, Croatia
b
Lesnina d.o.o., Zagreb, Croatia
c
Institute of Production Engineering, Faculty of Management, University of Technology, Poland
*
Abstract – The importance of planning cannot be stressed enough. By analysing the company and its
future operations objectively, one reveals its strengths and weaknesses, recognises potential hazards,
discovers new revenue opportunities and achieves planned business objectives. Planning helps in
detecting problems early, discovering their causes and finding an efficient solution, and also allows to
avoid completely some problems while they are still small. This paper examines the ways and methods
of production planning in wood processing and furniture manufacturing. With the aid of available
literature, a detailed planning process is demonstrated, covering the topics such as management,
control and planning with their respective roles, goals and purpose, as well as environment-dependent
dynamic planning. The planning theory is compared to the practice to underline commonly
encountered problems.
planning process / regulation of planning time / process management / planning preparation
1. IDEA OF PLANNING AND SYSTEM OF PLANNING
Planning is defined method of forming desires; the opposite of panning is improvisation.
It is thinking ahead. Planning definition in functional sense is that planning is sententious
preparation of future activities, methodological-systematically process of cognition and
solving future problems, perspective sententious activity which determines future activities
ahead. Planning is a process of determining what organisation wants to achieve and deciding
how to achieve those goals.
It includes: prediction on possible environment constellation and achievable way of
acting in future period and determining ways of acting for achieving given planned goals in
accordance with management philosophy.
One of the most important entries of planning is focus on the future. However, like
planning, prognoses are also focused on future. While planning determines which decisions
should be brought in order for future actions to occur, prognosis predicts future actions that
will probably occur. Thereby, prognosis is necessary and very important part of decision
process. However, in contrary to planning, prognosis is not active function; it is one of
planning methods.
1.1. Function, purpose and goals of planning
Planning as controlling tool has a special role in wood manufacturing and wood
processing companies (GRLADINOVIĆ, 1999). It contributes to important goals achievement,
important measures undertaking, design and evaluation of expectations and attitude, work and
response and contact improvement inside the company. Basic functions of planning are:
 success insurance, that is efficiency growth due to resources and goals planning
 risk cognition and reduction with the help of anticipative analysis and solving future
problems
 flexibility growth considering, for example, creation and assurance of future work
space
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 complexity reduction, for example, by establishing alternative future actions and
excluding certain situations and events
 creating synergetic effects, for example, inside boundaries of individual measures
dependence cognition.
The purpose of planning is in excluding unexpected events probability decrease, in order
to minimise chosen measurement risk. Basic guidance idea of properly understood business
planning is that planning is a learning process, and deviations are accepted as its definite
component.
Central goal of planning in company concerns two problems field control, whose
importance for business management constantly grows due to:
 constant adjustment needs: because of fast changes in numerous social, technical and
economical dimensions, probability of unexpected events and amplified complexity
in company is increased; generally growing dimension of company and
diversification of products and market demand new business structures.
It is considered that the basic elements of planning are:
 goals – what?
 premises – under what conditions?
 problem – why?
 measures – how?
 resources – what with?
 terms – when?
 carriers – who?
 results – what are the effects?
Considering the period of planning we can speak of time dimension between horizon and
point of planning. We can distinguish: long term planning, for period longer than 5 years;
medium term planning, for period between 2 and 5 years; and short term planning, for period
until one year.
1.2. Objects of planning
It is generally considered that the objects of planning can be: building businesses which
include building companies in organisational, technical and financial sense; business program,
which is product program for determined period; and company business, which is mutual
adjustment and exploitation of production factors, and depending on business process phase it
is separated on planning of acquisition, sale etc. (GRLADINOVIĆ, 1999).
Objects or matters of planning can be all objects of business activity. The following
classifications contribute to object planning clearness:
 periodicity: there is one-time planning (planning of formation, location etc.),
occasional planning (planning of merging, sanitation, stocks) and permanent planning
(planning of production, sales etc.)
 maturity: short term, medium term and long term
 needs and needs cover: according to this criteria needs are planned and faults are
determined, then, by needs cover planning those faults are removed
 planning process content: this aspect relies on planning process phases – goal
planning, activity planning, measures planning and resources planning
 business fields: planning of sale, production, finances, investments and employment
are basic fields of planning companies.
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2. OPERATION PLANNING – FUNCTION AND INSTRUMENTS
2.1. Planning process
Planning is sententious process of forming future, it is the process of sententious
progression in future possibilities, and thus it is in fact spiritual process. Planning process can
be defined as goal focused, chained sequence of individual information transforming activities
with certain goal. Planning process is observed as specific decision making process, specific
because it relates to future (SUJOVÁ, 2004). According to phase theorem, basic phases of
decision making process are: problem identification, information search, formation of
alternative decision making, alternative evaluation, choosing alternative and decision
conduction.
Simplified, we can talk only of four process phases: problem definition, solution
detection, optimisation and implementation.
Planning process occurs through certain stages, in first stage goals are defined (what is
wanted) in second stage they are measured and paths (how is it achievable).
Goal planning is extremely important and essential part of planning, because it enables
adjustment of different decision making carriers of different levels. Goal system is based on
variety of quantitative and qualitative goal concepts as outlines of desired company
development. It is considered that every company should aspire towards two operative goals:
achieving enough incomes (economical component), accomplishing and maintaining financial
balance (financial component) because long term non-realisation of those goals endangers
company existence.
Figure 1. Plait of goals organization (OSMANAGIĆ – BEDENIK, 2002)
In substantial sense planning process includes these phases and stages:
 goal analysis (defining goals and their content, relations between goals, forming
and forming goals)
 problem analysis (problem cognition, its structuration and forming)
 possibility analysis (searching for possibilities and their forming)
 prognosis (what will happen)
 evaluation (connecting values to alternatives)
 decision (choosing one possibility)
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

realisation
control (comparison of achieved and planned).
Planning instruments are techniques and methods which serve to planner as a support in
planning process. One of the simplest systematisations starts with dividing instruments on
qualitative and quantitative. Qualitative planning techniques are based on knowledge,
experience, understanding, thinking and intuition, and are especially applied in analysis
phases, searching for alternatives, their evaluation and decision making phase. Quantitative
planning techniques are based on mathematically-statistical actions and stretch from simple
time analysis chains to mathematically demanding procedures of optimisation.
Table 1. Quantitative and qualitative techniques of planning (OSMANAGIĆ, 2002)
Planning techniques
qualitative methods
quantitative methods





Decision Tree
Decision Table
Delphi method
Scenario techniques
Creative techniques:
- Brainstorming
- Method 635
- Sinectic
- Morphological analysis
 Time Series Analysis
 Exponential smoothing:
Trend Extrapolation
- Moving Average Method
 Regression Analysis
 Methods of Mathematical Programming
- Linear Programming
- Nonlinear Programming
- Dynamic Programming
- Parametric and Stochastic Programming
- Heuristic Programming
- Simulation
 Special Optimization Procedures
 Network Planning Technique
 Benefit Analysis
Decision tree is applied when complex and insecure decision situations condition
multiple solutions. Different solution paths together with their consequences are shown as tree
branches. Decision point serves as starting point; alternative solutions are shown as decision
branches.
Preparation of planning includes information acquisition, plan guideline elaboration and
plan guideline documenting.
Planners are over flown with information, of which many are not usable. There is a
problem with finding relevant information for planning in such enormous quantity of
information. Knowing different types of information and distinguishing criteria is very useful.
There are original (primary) and derived (calibrated) information. Original are acquired by
direct information search, and derived are result of transmission, translation or reconstruction
of individual information. Information sources are very important, therefore internal and
external information sources are distinguished.
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During determination of current information state, control question lists are helpful:
 Which external information is acquired regularly and which occasionally?
 Which internal information is acquired regularly and which occasionally?
 Is the information complete?
 What does their possible incompleteness refer to?
 Does available information fulfil their purpose?
 Is the information already relevant for decisions?
 Is the information reliable and correct?
 Is the information precise?
 Can the information be evaluated?
 Is the information compatible with information needs of other fields?
In relations of offer, request and need there is an overlap; the bigger the common field,
the better role fulfilment information system has, as well as reporting system, which is its
important part.
Legend: 1- information offered, but not
requested, 2 - information requested, but not
offered, 3 - information necessary and
requested, but not offered, 4 - information
offered and requested, but not necessary, 5 information offered, but neither necessary not
requested, 6 - information requested, but
neither offered not necessary, 7 - information
requested, but not necessary and needed
Figure 2. Relationship between supply, demand and need for information (BOLFEK, 2004)
2.2. Operation planning
Operation planning is short term planning for period up to one year, and it meets market
and tax-legal accounting period. It is derived from strategic planning and it contributes to
achieving planned strategy, it is more detailed and specific. Operation planning is conducted
permanently and minimally on the level of business fields: sales, production, acquisition,
finances and employees. Its task is sententious analysis with purpose of optimal usage of
given potential effects with given products on current market.
Operation planning is tightly connected with term of budgeting, accounting. Usually,
budget or account is monetary plan (especially cost) which, according to responsibility fields,
shows (costs) values for certain planned period (a year or less), obligatory for relative
responsibility carriers.
In company practice, long term investment budgets and financial budgets are often
created.
Operations planning basic activities are: sale planning, production planning, acquisition
planning, financial planning and employees planning.
Marketing plan, together with conduction and control of marketing activities, is important
part of marketing strategy, which is part of company's business strategy.
Marketing planning is wider term which includes: plan for sales, traffic, measures and
cost.
Acquisition plan is derived from sales, production and stock plan, and directly influences
result plan.
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Acquisition plan can be analytically observed as: planning acquisition program
(acquisition and storage goals) and planning acquisition measures.
2.3. Harmony of planning process
Mutual dependence of individual partial plans is particularly stressed, together with their
relation towards business plan: substantial, time and hierarchy mutual connection.
Mutual connection consequences are disclosed in fact that activities and measures cannot
be determined separately in one part of overall plan; they must be determined in relation to
other partial plans. Without mutual coordination, each field aspires to concentrate on its own
activities, and by planning process compatibility between different individual priorities and
orientations is achieved.
Harmonisation is a wider term which includes coordination as horizontal adjustment on
different hierarchy levels.
2.4. Instruments of coordination
Instruments of coordination are auxiliary assets for achieving partial plan compatibility
on the same hierarchy levels. There are different coordination instruments classifications:
most commonly direct and indirect coordination.
Figure 3. Relationship between supply, demand and need for information (Indirect Instruments of
Coordination (OSMANAGIĆ, 1998)
Direct coordination is applied in small companies, where all partial plans are united and
coordinated through whole overall plan. Coordination task takes central planning place.
By company size growth internal complexity and dynamics increase, so that indirect
coordination instruments are used.
2.5. Problems of planning in practice
Since complexity reduction, by information gathering, is one of basic planning tasks,
organisation culture can support as well as obstruct planning process.
Focusing on central values – organisation vision is increased by preparedness of
conducting strategies, goals and measures in daily work.
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Implementation and application of planning in business practice is followed by problems
and limitations. Organisationally conditioned limits and behaviour conditioned limits are
among the most important ones.
Organisationally conditioned limits can be separated into those construction conditioned
and process conditioned.
Construction conditioned limits relate to problem defining of planning task carriers.
Although the advantage goes to headquarters task planning organisation, due to hierarchy
status knowledge concentration, deficiencies are seen in predominant focus of linear
managers on daily work and neglecting coordination with strategic controlling dimension.
How important and common planning problems in practice are, says their list: planning
and routine of daily work, linear manager dislike of planning, insecurity, optimistic planning
mentality, silent reserves, improper plans, plan violation, plan revision, information
concealment and manipulation, task carrier’s bureaucratic behaviour, neglecting strategic
aspects, neglecting whole organisation interest and department egoism and self-obligation
escalation.
Planning preparation varies from company to company, where mutual understanding is
stressed, not theoretical tasks no one understands.
Described repulses and planning problems exist in many companies and they should be
reckoned. The problems are decreased by cooperation and communication with individual
fields, not by authority usage.
3. CONCLUSION
Under the influence of external and internal conditions in a company, and influence of
growing competition, continuous management development is necessary, as well as whole
company’s structure development. It is important to follow environment dictated standards
and plan further development based on gathered information. Planning preparation varies
from company to company, where mutual understanding is stressed, not theoretical tasks no
one understands. Described repulses and planning problems exist in many companies and
they should be reckoned. The problems are decreased by cooperation and communication
with individual fields, not by authority usage. It is necessary to constantly have in mind that
planning processes are often inefficient due to inaccurate attitude towards planning. Plans
themselves do not determine company’s destiny; manager’s experience and intuition are also
necessary. Doubt and repulse towards planning do not necessarily mean bad intentions and
adjustment; they can be consequence of improper attitude and relation between planer and
controller.
4. REFERENCES
AVELIN-HOLJEVAC, I. (2004): Planning and Controlling. RRIF, 8 (10): pp. 66-69.
BOLFEK, B. (2004): Requests information system of controlling. RRIF, 8 (3): pp. 56-62.
FIGURIĆ, M. (2003): Menadžment troškova u drvnotehnološim procesima. Sveučilišni udžbenik,
Sveučilište u Zagrebu, Šumarski fakultet, pp. 1-249.
GRLADINOVIĆ, T. (1999): Upravljanje proizvodnim sustavima u preradi drva i proizvodnji namještaja,
Sveučilišni udžbenik, Sveučilište u Zagrebu, Šumarski fakultet, pp. 1-296.
MAJDANDŽIĆ, N. (1994): Kompjuterizacija poduzeća. Strojarski fakultet u Slavonskom Brodu,
Slavonski Brod.
OSMANAGIĆ, B.N., (1998): Kontroling: abeceda poslovnog uspjeha. Školska knjiga, Zagreb.
OSMANAGIĆ, B. N., 2002: Operativno planiranje. Školska knjiga, Zagreb.
SUJOVÁ, A., 2004: SWOT analysis – information support for building development strategy of the
Slovakian wood industry. Drvna industrija 56 (4): pp. 199-207.
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Effect of Cell-Wall Angle on the Uniaxial Crushing Behaviour of Paper
Hexagonal Honeycombs
SMARDZEWSKI Jerzya*– MAJEWSKI Adama – PREKRAT Silvanab
a
Poznan University of Life Sciences, Poznan, Poland
b
University of Zagreb, Zagreb, Croatia
*
Abstract – The following factors: paper mass, apparent density as well as cell shape and dimensions
exert a significant impact on the stiffness and strength of cell panels. In the available literature on the
subject, there are no papers reporting research results on the stability of paper honeycombs depending
on the cell-wall inclination angle and apparent density of a honeycomb. The objective of this research
project was to determine the influence of the cell-wall angle of irregular hexagonal cells as well as
their apparent density on the stability of a paper honeycomb. The investigations were realised by
carrying out experimental tests and then comparing the obtained results with the results of numerical
calculations. Empirical tests were conducted using cores made from paper honeycombs of hexagonal
cells differing with respect to wall inclination angles which ranged from 55° through 66° to 82°. It was
demonstrated that together with the increase of the cell-wall gradient above 55°, the value of the
honeycomb critical force as well as its apparent density also increased. For the angle of 82°, despite
high apparent density, cell slenderness increased and its stability decreased. In addition, numerical
models were elaborated sufficiently correctly ensuring convergence of the calculations with the results
of experimental measurements.
paper honeycomb / cell-wall angle / crushing / numerical analysis / experiment
1. INTRODUCTION
Layered structures with a cell core are widely used as secondary systems in aeronautics
and car industry as, for example, bonnets or doors. Modelling of small velocities, low impact
energies leading to decreases of construction strength by 50 % remain among the main
challenges for designers. Because this kind of action is characterised by the same result as the
quasi-static loading, scientific investigations focus on studies of the core behaviour – i.e. of
the honeycomb during compression. The phenomenon of crushing has been well recognised
over the years but its mechanism has not been comprehensively described and the proposed
model cannot fulfil industrial requirements (GUPTA – ABBAS 2000; SINGACE, 1999;
WIERZBICKI, 1983). More comprehensive studies on mechanical properties of cell panels
embraced structures manufactured from metal. These studies described strength properties of
aluminium sandwich type panels in the following tests: bending, compression and stability
(JEN et al., 2008; KHAN, 2006; PAIK et al., 1999; SAID et al., 2009). Orthotropic properties of
an aluminium core in the form of a honeycomb were determined (SCHWINGSHACKL et al.,
2006). A novel approach to the analytical description of the core structure was presented and
a new solution consisting in combining core elastic properties with the geometry and
mechanical properties of the material from which the core was manufactured was proposed
(MERAGHNI et al., 1999).
Usually, cell structures are employed as stratified systems with metal facings. In their
investigations, TAN et al. (2007) ascertained the effect of different assumptions, materials,
facings as well as loading on the absorption energy and deformations of the applied cell
structures. In those investigations, the above researchers employed three-dimensional models
of finite elements corresponding to the mechanics of the following orthotropic bodies:
composite fabrics, wood, glass, aluminium alloys 2024-T3 as well as fibrous anisotropic
composites T-300. The obtained results indicate that the deformation and energy dispersion of
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the surface deformation of the examined structure depended, in a significant way, on the
number of layers, material used as facing, load thickness and area. PETRAS – SUTCLIE (1999)
analysed models of damages of laminated stratified aluminium beams with a Nomex core in
the form of a honeycomb. These researchers presented theoretical models which utilised the
mechanics of a honeycomb and the classical beam theory. They demonstrated that in the
course of a three-point bending, there was a correlation between the type of damage and
construction bearing capacity and laminate thickness and the length of the honeycomb. In
addition, the results of theoretical calculations were corroborated by experimental
measurements. ZHOU et al. (2012) determined plastic behaviour of a Nomex honeycomb in
the course of shearing combined with compression. Moreover, the influence of the sample
inclination angle on plastic behaviour during a complex loading state was assessed. Two
different cases of sample damage were registered: plastic buckling and fracture of cell walls.
The elaborated research results provide an excellent contribution to the elaboration of
constitutive models of Nomex cell panels in complex loading state.
Hexagonal honeycomb cells in a transverse plane provide exceptional cushioning
material. Their constructional parameters and impact velocities exert a significant influence
on the consequences of the action. In experiments conducted by DEQIANG – WEIHONG (2009),
using the finite element method, they investigated correlations between construction
parameters of the honeycomb and strain after the loss of stability at the impact velocities
ranging from 3 to 250 m/s. They demonstrated that for constant honeycomb parameters,
strains were proportional to the square of the impact velocity. Moreover, HU et al. (2013)
studied the effect of the cell-wall inclination angle on the dynamic crushing of the honeycomb
in transverse plane. They demonstrated that the size of crushing depended on the apparent
density of the honeycomb and the inclination angle of cell walls. The highest strength was
observed in cells with wall inclination angle equalling 45o. It should be added that significant
orthotropic properties of the core become apparent when the inclination angle exceeds 30o.
Few papers deal with modelling of mechanical properties of cell panels with a paper
honeycomb (SEIDL, 1956). SAM-BREW et al., (2011) carried out investigations on the effect of
the type of paper, cell orientation, their height and arrangement on stiffness and strength of
cell panels. WANG – WANG (2008) as well as PING – WANG (2010) determined the effect of
density and moisture content of cell panels on paper core stability. Furthermore, a
mathematical model was developed of the dependence between absorption energy of cell
panels and their moisture content (WANG – PING 2010). The impact of the auxetic core
structure of the cell panel and the kind of the facing material on cell panel stiffness was
discussed in a paper by SMARDZEWSKI (2013). SMARDZEWSKI – PREKRAT (2012)
demonstrated that cores of cell panels manufactured from HDF facings and irregular
hexagonal honeycomb cells level out well strain differences between panel layers. In addition,
paper mass, apparent density and shape and dimensions of cells exert a significant influence
on cell panel stiffness and strength. It was found that during the process of bending of cell
panels with a paper core, multiple buckling of cell walls takes place (SAM-BREW et al., 2011).
However, no articles can be found discussing research results of paper honeycomb stability
depending on the inclination angle of cell walls and apparent density of the honeycomb.
The objective of this research project was to determine the effect of the inclination angle
of irregular hexagonal cells and their relative density on the stability of a paper honeycomb.
Experiments were realised by carrying out experimental tests and comparing the obtained
results with numerical calculations.
Paper honeycomb cores with hexagonal cells of hc – 10 mm height, paper thickness of t =
0.2 mm and 140 g/m2 density were prepared for empirical investigations (Figure 1). Paper
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WOOD IS GOOD
honeycomb in pressed form (for stretching) was obtained from the Company Axxion
Industries Poland Ltd. Cells were stretched in such a way as to obtain three structures
differing with regard to the size of the cell and cell-wall angle inclination (Figure 2). A-type
cells were characterised by maximal stretching ∆L. The extension of B and C cells amounted
to 0.5 ∆L and 0.25 ∆L, respectively. The obtained honeycombs were used to obtain ten
samples each with dimensions 10 mm x 50 mm x 50 mm (Figure 2). The surface of samples
was scanned and then extended in the CAD system to the height of 10 mm (Figure 3).
Dimensions of hexagonal samples are illustrated in Figure 4. As evident from this Figure, the
obtained cells differed with respect to their length and angle of wall inclination. Walls of the
A-type cells were inclined at the angle of φ≈55°, while those of B and C cells, at angles of
φ≈66° and φ≈82°, respectively.
In all, 30 samples were prepared and were subjected to uniaxial compression using for
this purpose a Zwick 1445 test machine applying loading velocity of 10 mm/min. The applied
force was measured with the accuracy of 0.01 N and deflection with up to 0.01 mm accuracy.
Figure 1. Model of a hexagonal core cell
Figure 2. Samples of hexagonal cells employed in experiments:
A – φ=55°, B – φ=66°, C – φ=82°
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Figure 3. Model of cells created in CAD on the basis of scanned image
Figure 4. Cell dimensions depending on the wall inclination angle:
A – φ=55°, B – φ=66°, C – φ=82°
It was further decided to determine the influence of the honeycomb apparent density on
the value of the critical force causing cell-wall buckling. Relative density of the paper
honeycomb depends on its structure, i.e.: the thickness, length and inclination angle of cell
walls. This is expressed by the following quotient:
(1)
where: pc – density of the paper honeycomb, pp – density of the paper forming the
honeycomb.
Assuming further that b = c = d = 1 and assuming that
(2)
and,
(3)
where: mp – mass of the paper forming the honeycomb, Vc and Vp – respectively, volume of
the paper core and volume of paper, pc and pp density amounts to:
(4)
!
"
!
#
!#
!# $
!
"
!
#
!#
!# $
(5)
hence,
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(6)
WOOD IS GOOD
3. NUMERICAL ANALYSIS
Three solid models of single cells were prepared for numerical calculations (Figure 5).
The models consisted of a paper core of hexagonal cells to which elastic properties of paper
Ep = 2000 MPa were assigned (SZEWCZYK, 2010; UESAKA et al., 1979).
Figure 5. Solid models used for numerical calculations:
A – φ=55°, B – φ=66°, C – φ=82°
Next, appropriate numerical models were designed employing for this purpose 20-node,
brick-type finite elements in the environment of the Autodesk Simulation Multiphysics ® 2013
software. The models were then supported in such a way as to bring about cell wall buckling
under the influence of uniaxial compression. First, the value of the critical force causing loss
of stability of each of the examined models (A, B and C) was calculated. Next, calculations of
the post buckling behaviour of the examined systems were performed for loads determined in
this manner.
Figure 6 presents an example picture of a honeycomb subjected to uniaxial compression.
It illustrates the form of buckled cells following their loss of stability. It is evident from this
Figure that top edges of cell walls as well as surfaces of side walls underwent destruction.
Figure 7 illustrates the dependence of force on displacement. It can be noticed on the basis of
this Figure that the value of the critical force PCR depended quite clearly on the inclination
angle of the honeycomb cell walls. The highest PCR value was observed in the case of cells
with the cell wall inclination angle of φ=55°. The lowest critical force occurred during
compression of the honeycomb whose cell walls were inclined at the angle of φ=82°. In
addition, once the critical load was exceeded, even slight increases or decreases of force were
accompanied by large displacements confirming loss of stability of cell side walls. Similar
runs were reported by other researchers investigating the stability of aluminium, plastic or
paper honeycombs (DEQIANG – WEIHONG, 2009; HU et al., 2013; MERAGHNI et al., 1999;
PAIK et al., 1999; PETRAS – SUTCLIFFE, 1999; PING – WANG, 2010; SAID – TAN, 2009;
SCHWINGSHACKL et al., 2006; SEIDL, 1956; SINGACE, 1999; WANG – PING, 2010; WANG –
WANG, 2008; WIERZBICKI, 1983; ZHOU et al., 2012).
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Figure 6. Deformation of cells measuring 10 mm x 50 mm x 50 mm
following a uniaxial compression test
Figure 7. Stiffness of cells measuring 10 mm x 50 mm x 50 mm
during uniaxial compression: A – φ=55°, B – φ=66°, C – φ=82°
Figure 8. Area of pressure and critical force for cell wall samples measuring
10 mm x 50 mm x 50 mm: A – φ=55°, B – φ=66°, C – φ=82°
As demonstrated on samples measuring 10 mm x 50 mm x 50 mm, the value of the
critical force depended on the inclination angle of side cell walls. Moreover, this angle was
also found to affect changes in the pressure area as well as cell relative density (Equation 6).
Figure 8 presents correlations between the pressure area and value of the critical force. It is
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evident that together with the growing pressure area, the value of the critical force also
increased reaching the following values: 1299 N, 1587 N and 2002 N for A, B and C samples,
respectively. Simultaneously, the area of pressure increased from 210.1 mm2 to 282.7 mm2
and 773.6 mm2. In the case of A and B models, the pressure area increment of 34.5 % resulted
in the increase of the critical force value by 22.1 %. The above-mentioned differences for B
and C models amounted to 73.6 % and 26.1 %, respectively. Therefore, it can be concluded
that pressure area increments were not accompanied by proportional increases of the critical
force. This may be attributed to the fact that honeycomb is not made up of ideally hexagonal
cells. It can be observed from Figure 1 that cells are characterised by different lengths of
walls. Therefore, their stabilities vary and affect non-linear value changes of the critical load.
Figure 9 illustrates the way of deformation of individual cell walls. The left column of images
illustrates the form of buckling under the influence of the critical load, while the right column
shows the form of deformation after the loss of cell wall stability. It is evident from this
Figure that the critical load caused, primarily, deformations of top edges of cell walls as well
as buckling of side walls. Because of their different lengths, it is the longest walls that
undergo buckling first. Places where the cells join, forming perpendicular ribs undergo only
compression. Once the critical loading is exceeded, edges and walls of cells undergo further
deformations. Vertical ribs also undergo buckling. In addition, it can be observed that the
inclination angle of cell walls exerts a significant influence on the status of cell deformations
of the honeycomb. Greater wall inclination angles make cells slender and sensitive to
buckling. Figure 10 illustrates values of critical forces calculated numerically for a single cell.
These values were collated with the results of laboratory measurements together with values
of pressure areas and cell relative density. The smallest critical load of one cell was found to
occur in the case of model C. It is a slender cell of small pressure area (9.33 mm2) and of high
relative density (1.01). In the case of this cell, the loss of stability occurs as a result of a onesided buckling of all cell walls. Despite the fact that the cell is characterised by high relative
density, nevertheless it exerts impact on the increase of stability of a system made up of many
cells. In this case, stability is affected by a small pressure area and slenderness of the cell.
Comparing the results of numerical calculations determined for this cell with empirical
values, it should be stressed that the numerically determined value of the critical force of
30.68 N exceeded by 26.9 % the value of 24.15 N established in the laboratory. Cell B is
characterised by the pressure area of 9.50 mm2 and relative density of 0.51. In this case, the
experimentally determined critical force causing loss of cell wall stability amounts to 53.33 N.
However, numerical calculations deliver a higher value which amounts to 81.08 N and
exceeds by 52 % laboratory values obtained empirically. The largest pressure areas were
determined in A cells and their apparent density amounted to 0.43. Numerically calculated
value of the critical force of 66.5 N exceeds the value determined experimentally of 59.74 N
by 11.3 %. On the basis of the above-performed comparisons as well as comparisons with the
results of measurements of the stability of a honeycomb made up of many cells, a regularity
emerges indicating that critical loads of a honeycomb and a single cell depend on the
inclination angle of cells. Together with the increase of this angle to above 55°, the stability of
the structure increases. In the case of honeycomb, the critical force increases together with the
increase of relative density. A similar correlation can be observed in the case of single cells A
and B. The C cell, due to its considerable slenderness easily loses its stability despite high
relative density.
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Figure 9. Wall buckling of single cells for critical and after-critical loads:
A – φ=55°, B – φ=66°, C – φ=82°
Figure 10. Relative density and critical force for single cells:
A – φ=55°, B – φ=66°, C – φ=82°
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5. CONCLUSIONS
On the basis of the analysis of the obtained research results, the following conclusions can
be put forward:
− together with the increase of the inclination angle of cell walls above 55°, the value of the
critical force of the honeycomb as well as its relative density increased,
− the stability of a single cell depended on the inclination angle of walls and increased
together with its growth,
− for the 82° angle, despite high relative density, cell slenderness increases and its stability
declines,
− numerical models were designed sufficiently correctly which assured convergence of
calculations with the results of empirical measurements.
6. REFERENCES
DEQIANG, S.; WEIHONG, Z. (2009): Mean in-plane plateau stresses of hexagonal honeycomb cores
under impact loadings. Composite Structures 91: pp. 168–185.
GUPTA, N.K.; ABBAS, H. (2000): Mathematical modelling of axial crushing of cylindrical tubes.
Thin-walled Structures 38: pp. 355-375.
HU, L.; YOU, F.; YU, T. (2013): Effect of cell-wall angle on the in-plane crushing behaviour of
hexagonal honeycombs. Materials and Design 46: pp. 511–523.
J EN, Y.M.; CHANG, L.Y. (2008): Evaluating bending fatigue strength of aluminium honeycomb
sandwich beams using local parameters. International Journal of Fatigue 30: pp. 1103–1114.
KHAN, M.K. (2006): Compressive and lamination strength of honeycomb sandwich panels with strain
energy calculation from ASTM standards. Journal of Aerospace Engineering 220: pp. 375-386.
MERAGHNI, F.; DESRUMAUX , F.; BENZEGGAGH, M.L. (1999): Mechanical behaviour of cellular
core for structural sandwich panels. Composites Part A 30: pp. 767–779.
PAIK, J.K., T HAYAMBALLI, A.K., KIM, G.S. (1999): The strength characteristics of aluminum
honeycomb sandwich panels. Thin-Walled Structures 35: 205–231.
PETRAS, A.; SUTCLIFFE, M.P.F. (1999): Failure mode maps for honeycomb sandwich panels.
Composite Structures 44: pp. 237-252.
PING, Y.; W ANG, Z.W. (2010): Plateau Stress of Paper Honeycomb as Response to Various Relative
Humidities. Packag. Technol. Sci. 23: pp. 203–216.
SAID, M.R.; T AN, C.F. (2009): Aluminium honeycomb under quasi-static compressive loading: an
experimental investigation. Suranaree Journal of Science and Technology 16: pp. 1-8.
SAM -BREW, S.; SEMPLE, K.; SMITH, G. (2011): Preliminary experiments on the manufacture of
hollow core composite panels. Forest Products Journal 61: pp. 381-389.
SCHWINGSHACKL, C.W.; AGLIETTI, G.S.; CUNNINGHAM, R.R. (2006): Determination of honeycomb
material properties: Existing theories and an alternative dynamic approach. Journal of
Aerospace Engineering 19: pp. 177-183.
SEIDL, R.J. (1956): Paper-honeycomb cores for structural sandwich panels. In: Forest Products
Laboratory. Forest Service U. S. Department of Agriculture. Madison 5, Wisconsin.
SINGACE, A.A. (1999): Axial Crushing analysis of tubes deforming in the multilobe mode.
International Journal of Mechanical Sciences 41: pp. 865-890.
SMARDZEWSKI, J.; PREKRAT, S. (2012): Modelling of thin paper honeycomb panels for furniture. In:
Proceedings of the International Conference Ambienta “Wood is Good – With Knowledge and
Technology to a Competitive Forestry and Wood Technology Sector”. Croatia. October, 2012.
pp. 179-186.
SMARDZEWSKI, J. (2013): Elastic properties of cellular wood panels with hexagonal and auxetic
cores. Holzforschung 67 (1): pp. 87–92.
SZEWCZYK, W. (2010): Packaging Paper – Orthotropic Elastic Material. Przegląd papierniczy 66:
pp. 205-209.
T AN, X.; CHEN, X.; CONWAY, P.P.; YAN, X.T. (2007): Effects of plies assembling on textile
composite cellular structures. Materials and Design 28: pp. 857–870.
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UESAKA, T.; MURAKAMI , K.; IMAMURA, R. (1979): Biaxial tensile behaviour of paper. Tappi
Journal 62: pp. 111-114.
WANG, Z.W.; PING, Y. (2010): Mathematical modelling of energy absorption property for paper
honeycomb in various ambient humidities. Materials and Design 31: pp. 4321–4328.
WANG, D.M.; WANG, Z.W. (2008): Experimental investigation into the cushioning properties of
honeycomb paperboard. Packag. Technol. Sci. 21: pp. 309-316.
WIERZBICKI, T, (1983): Crushing Analysis of Metal Honeycomb. International Journal of Impact
Engineering 1(2): pp. 157-174.
ZHOU, Z.; WANG, Z.; ZHAO, L.; SHU, X. (2012): Experimental investigation on the yield behavior of
Nomex honeycombs under combined shear-compression. Latin American Journal of Solids and
Structures 9: pp. 515 – 530.
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Impact of the Economic Crisis on the Wood Industry Production in
Republic of Macedonia
STANKEVIK SHUMANSKA Miraa*– MELOSKA Živkaa – EFREMOVSKA Violetaa
a
Faculty of Design and Technology of Furniture and Interior - Skopje,
University Ss Cyril and Methodius - Skopje, Republic of Macedonia
*
Abstract - Wood industry production in the Republic of Macedonia, or wood processing and furniture
manufacturing in recent years, is facing a series of challenges and problems of a structural nature,
which, if not resolved promptly have a relatively high potential to threaten its competitiveness.
Moreover, recently, before this important traditional industry haltingly new problem - the economic
crisis, which hides the real danger further worsen its position in the industrial structure of the domestic
economy. The purpose of this paper is to analyze and identify the impact of the economic crisis on the
performance of wood industry sector. Consequences of this crisis are felt in terms of the volume of
industrial production especially in wood processing and the level of export activity, which have
negative trends or intense rate decline in the analyzed period (2006-2012 year). The level of
employment in wood processing and furniture production has increased in intensity studied period.
economic crisis / wood processing / furniture production / industrial production / employees /
export
1. INTRODUCTION
The global economic and financial crisis or recession, are strong economic characteristic
which in recent years affect all global economic trends. The recession has already received its
name in the global repository of economic science as the recession of late two thousands and
its intensity and size influence widely shake the economic foundations of the modern world.
There were many pessimistic thoughts to one side, but also predictions still have something
easier scenario out of the crisis faster economic recovery, on the other hand.
Regardless of which of these two considerations would undoubtedly lean we can say that
the impact of the crisis and the recession comes in a big way in the Republic of Macedonia in
its economic trends, and the broader social context. The impact of the economic crisis is
evident and the wood processing and furniture production, i.e. wood industry production in
the Republic of Macedonia. Given the impact of the crisis in a broader context, it is necessary
to determine the dynamics and intensity of the impacts of the crisis. To combat the crisis is
not enough to note that the present crisis periods and operating results are not good. Quality
fight the economic crisis in order to achieve a high degree of management crisis and out of
crisis, it is necessary to determine the impact of the crisis with all the repercussions of
dynamic performance and to design solutions proposed to minimize or overcome specific
crisis. The purpose is focused this paper, i.e. to analyze and identify the impact of the
economic crisis on the performance of activities of wood processing and furniture production
in the Republic of Macedonia.
2. FEATURES OF THE WOOD INDUSTRY IN THE REPUBLIC OF
MACEDONIA AND ITS PERFORMANCE
The wood industry is one of the traditional industries in the Republic of Macedonia. The
wood industry production consists mainly of the processing of wood and wood products and
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furniture manufacturing. But the entire process of production, analyzed by stages of
production mainly includes the following stages: wood processing, production of wood
products, furniture manufacturing and service performance on wood industry production.
Wood industry sector in the country stands out according to their characteristics. As one
of the recognizable those distinguished it from other industries and are considered as
advantages are as follows:
• Tradition of working with the existing infrastructure and production facilities, and
available workforce supported by attractive young people,
• Permanent export orientation of production,
• Relatively low value of investments in production facilities and per employee,
• Existence of the wood industry cluster, and
• Relatively ecologically acceptable industry.
As a consequence of the real economic situation in which the state, the wood industry is
faced with a number of limitations and weaknesses related to:
• Insufficient size and structure of exports and imports, which are due to the loss of
important markets and unorganized approach to foreign markets, emphasized the
import of wood products industry from EU countries and beyond, as well as the
inability to finance exports and investments (insufficient) own accumulations,
• Low utilization of production capacity,
• need for technological modernization (computerization and automation of
production)
• Low certification and poor quality control,
• Lack of a recognizable brand of Macedonian wood industry,
• compete price which is the biggest obstacle to Macedonia's exports of wood products
and furniture, where the competent authorities are expected introduction of incentive
(incentive) measures to reduce the cost of production,
• Low energy efficiency of technological processes and negligent use of wood waste
as biomass for the production of renewable energy.
Participation that wood industry has in the total number of employed persons in the
Republic of Macedonia, as well as in total exports and in creation of total GDP is shown in
Table 1.
Table 1. Participation of the wood industry of the Republic of Macedonia in the total GDP (value
added), exports and employment (in %)
Participation of wood industry in
2006
2007
percent in
total GDP (value added)
0,6
0,5
total exports
0,8
1,0
total employees
1,7
1,6
Source: State Statistical Office of Macedonia, Publications
2008
2009
2010
2011
0,6
1,1
1,6
0,6
1,3
1,6
0,4
1,0
1,5
0,4
0,9
1,3
The share of this industry in the structure of total value added and total GDP shows a
trend of slight movements in variables dynamics. On average 0.6 % in 2006 falling to 0.5 %
in 2007, and in 2010 reached the level of around 0.4 %. This level is maintained in 2011. As
its share in total exports and here we have a trend variable movements slightly more
pronounced dynamics where the period 2007 - 2009 increased from 1.0 % to 1.3 %, and in
2010 dropped again to 1.0 %. The continuity of decline continues in 2011 to 0.9 %.
The biggest share of the wood industry represents its participation in total employment in
the Republic of Macedonia. From Table 1 it is seen that its impact on overall employment
declines continuously from 1.7 % in 2006 to 1.3 % in 2011.
Previous data show that the performance of this traditional industry, although still less
significant impact on the industry and economy of the Republic of Macedonia. Therefore
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WOOD IS GOOD
there is a real need for taking measures for easier overcoming the negative effects produced
by the economic crisis, thereby preserving its competitiveness in the market.
Presented specifics point to the fact that the wood industry of the Republic of Macedonia
is a very fragile industry of which lie ahead and some restructuring. The latest economic crisis
which unexpectedly long exists now a threat to wood industry sector in the country.
In order to realize the economic consequences of recession, will make a brief review of
its impact on wood industry production, the export sector and the number of employees in this
sector. The relevant period of time is 2007 - 2012 year. Exactly in this period of economic
crisis intensity is present, so that the economic performance of the wood industry is exposed
to the direct impact of adverse changes from the crisis.
3. IMPACT OF ECONOMIC CRISIS ON WOOD INDUSTRY PRODUCTION
The situation in the industrial production of wood industry will show through the base
index of industrial production as the average of the base 2005 according to data from the State
Statistical Office of the Republic of Macedonia. Base index of industrial production measures
the change in industrial production compared with a basic period (in this case 2005) to reflect
a kind of its normal position.
Base index of industrial production (2005 = 100) in the manufacturing industry, wood
processing and furniture production are shown in Table 2.
Table 2. Index of industrial and wood industry production
Year
2007
2008
2009
2010
2011
2012
Base index of industrial production
(2005 = 100)
Manufactiring
Furniture
Wood procesing
industry
poduction
112,2
93,4
83,8
118,8
71,4
223,4
106,5
41,8
159,9
98,5
61,7
128,6
103,9
48,5
159,5
97,3
52,3
136,3
Source: State Statistical Office of Macedonia, Publication - Industry, 2007-2012
The movement of the base index of production in the manufacturing industry indicates
that in the first half of the period 2007-2010 compared with the average since 2005 has seen a
slight decline of 98.5 %, and in 2011 a small increase of 103.9 % and in 2012 again fall to
97.3 %. This means that the recession back industrial production level of 2005, although
marked by a continuous upward trend.
In terms of total industrial production base movement index wood industry production
especially in the wood processing indicates that this branch as a whole is facing a crisis. The
dynamics is the drastic change in terms of what should be a normal condition in the base 2005
(reducing production of 48.5 % in 2011 and 52.3 % in 2012).
Unlike the movement of the base index for processing wood, the same at production of
furniture has a variable dynamic. Except in 2007 where the base index is below the level of
2005 (83.8 %), the base index of industrial production of furniture increased. The largest
increase recorded in 2008 (223.4 %) to the 2012 decline of 136.3 % compared to the average
of 2005. The level of wood industry production in analyzed period (2007-2012), especially in
wood processing is not the level that is recognized in respect of representative 2005.
Production of furniture is characterized by dynamic growth in the studied period.
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WOOD IS GOOD
4. THE IMPACT OF ECONOMIC CRISIS ON THE NUMBER OF EMPLOYEES IN
THE WOOD INDUSTRY
Wood industry participates with average from 1.5 % in the total number of employed
persons of the Republic of Macedonia in the period 2006 - 2011. The influence of the number
of employees in this sector is analyzed through basic index of annual change of staff in the
sector and the manufacturing industry. The base year is 2005, when the great door begins to
announce economic crisis in 2007 has had its beginning. Data were obtained by the State
Office of Statistics and shown in Table 3.
Table 3. Index of employed in manufacturing and wood industry
Indices of employees
(2005 = 100)
Year
2007
2008
2009
2010
2011
2012
Manufactiring
industry
96,2
96,0
89,5
89,3
90,3
87,4
Wood procesing
88,5
93,0
86,5
114,0
112,5
111,7
Furniture
poduction
94,7
105,5
103,1
118,7
122,4
118,9
Source: State Statistical Office of Macedonia, Publication - Industry, 2007-2012
Movement of the basic index of employees in the average of 2005 shows an increase in
wood processing and furniture manufacturing, as opposed to total employment in an industry
where there is a tendency of falling within the observed period (Table 3). It is slightly more
pronounced increase in staff in the production of furniture in the period 2007 - 2012 has seen
a growth index of employees by 22.0 % compared to 2005. In contrast, the processing of
wood is less noticeable intensity increase employment by about 14.0 % compared to 2005.
Base year index employed in the manufacturing industry decreased by nearly 13.0 % in the
analyzed period.
From the foregoing it can be seen that the economic crisis has reduced the number of
employees in the total industry and this negative impact is still present and further deepens.
This is not the case with the wood industry sector where is present trend of increasing
employment and in wood processing and the production of furniture.
5. ECONOMIC CRISIS AND EXPORT FROM THE WOOD INDUSTRY
The economic crisis whose effects are felt in the domestic economy is basically caused
by reduced aggregate demand for goods and services in the world, especially in developed
countries. Given the link between domestic wood industry to foreign markets, in terms of raw
materials, intermediate goods and finished products, there is a real risk of deterioration in
exports from this sector. Analysis of export of wood industry was based on the available data
are given in Table 4. Data were obtained from the State Statistical Office of the Republic of
Macedonia and analyzed for the period 2006 - 2011 year.
From the data in Table 4 can be seen that the impact of the economic crisis on exports of
wood industry has variable dynamics in the analyzed period. According to the annual index
change can be said to be of positive 73.2 % growth in exports in 2007 compared to 2006, in
2008 it exported about 22.7 % compared to 2007, which means that the trend increased export
declines. The index of annual change in 2009 shows no decline in exports even - 21.5 %
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compared to 2008 when it realized the biggest export of wood industry in the analyzed period.
In the period 2010 - 2011 year, we have increased the index of annual change in the
relationship of 2009 and 2010 from 1.4 % to 10.1 % while it can be said that has not yet
reached the level of exports of wood industry since 2008.
Table 4. Movement of total exports and exports from the wood industry (in 000 U.S. $)
Participation of exports
Index year
Annual index
Exports of wood
of wood products, wood
change in exports of
change of
Year Total export products, wood
and furnitrure in total
wood products,
and furniture
total exports (%)
export (%)
wood and furniture (%)
2006
2415161
20368
0,8
2007
3398268
35268
1,0
40,7
73,2
2008
3990642
43257
1,1
17,4
22,7
2009
2708488
33947
1,3
-32,1
-21,5
2010
3351429
34417
1,0
23,7
1,4
2011
4455375
37902
0,9
32,9
10,1
Source: State Statistical Office of Macedonia - Publications - Department exchange between Macedonia and
abroad, 2006 - 2011, own calculations
If you compare the situation of total exports and exports of wood industry visible is the
fact that the level of reaction to the economic downturn is more pronounced than in the total
exports in wood industry sector. The index of annual change in total exports from positive
40.7 % in 2007 compared to 2006, already in 2008 compared to 2007 manifest decline of
17.4 %, and in 2009 compared to 2008 show a downward trend from even - 32.1 %. In the
next period, total exports tends to growth, so in 2011 when exports has most of the analyzed
period, the annual change in the index increases to 32.9 % compared to 2010.
According to previous exports of wood industry manifested stable trends in times of
economic crisis in terms of total exports, which is confirmed by dropping its percentage share
in the total exports of 1.3 % in 2009 when most of the impact is expressed crisis of just 0.9 %
in 2011 when the total export has the largest volume in the analyzed period.
The reasons for this state of Macedonia's exports, and in that context, exports of forest
industry is in the nature and character of the economic crisis, the structure of the export
structure of wood industry production and high dependence on exports from changes in
foreign income, and change in domestic industrial production. The economic crisis is
characterized by a decline in aggregate demand across countries in the world resulting in a
decline in national production, employment levels and at the national GDP. The export
structure and structure of wood industry production complement reasons for this situation.
Wood products and furniture fall into the category of consumer goods which in the
conditions of crisis have expressed very high degree of elasticity of demand depending on the
change in relative income. Unlike the category of so-called subsistence products that have
steady demand in terms of the change in income in a recession, most suffer sales of consumer
goods which includes wood products and furniture.
6. CONCLUSIONS
The wood industry is a traditional industry in the Republic of Macedonia with its
contribution to GDP formation, employment and total exports. It is characterized by a
structure in which participation has the processing of wood and wood products and furniture
manufacturing. Regarding the extent of finalizing production represented a classic production
and manufacturing known as buying supremely product. Wood industry production is
characterized by low economic efficiency, high production costs, production of standardized
quality and low international competitiveness.
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The advent of the global economic crisis that overtakes the industry undergoing
restructuring had an impact on its performance within the observed period.
The level of wood industry production in the period 2007-2012, especially in wood
processing is not on the level that is recognized in respect of representative 2005 when the
great door begins to announce economic crisis. Production of furniture is characterized by
dynamic growth in the analyzed period.
Economic crisis reduces the number of employees in the total industry and this negative
impact is still present and further deepens. This is not the case with the wood industry sector
where is present trend of increasing employment and in wood processing and furniture
production in the studied period (2007-2012).
Exports of wood industry analysis through annual index changes manifested stable trends
in times of economic crisis in terms of total exports for the period 2006 - 2011 year. This is
confirmed by dropping its percentage share in the total exports of 1.3 % in 2009, when most
evident is the impact of the crisis, only 0.9 % in 2011 when the total export has the largest
volume in the analyzed period.
In terms of the process of reorganizing wood industry sector continued impact of the
recession can additionally jeopardize the positive performance trend. Therefore, it is taking
emergency measures to allow easier overcoming the adverse effects of the crisis, until you
perform stabilization of global economic trends. As one of the important measures apart
granting soft loans to support the liquidity of companies of the wood industry, delay or
exemption of tax obligations, particularly in respect of salaries and benefits, export incentives,
measures in the field of social policy to support unemployed and so on. Considering the
nature of the crisis, the recovery of the level of aggregate demand and income from abroad
will automatically regenerate and condition of the wood industry, traditional industry with its
impact on the domestic economy.
7. REFERENCES
EFREMOVSKA, V., MELOSKA, Z., SIMAKOSKI, N. (2013): SWOT – Analysis of the wood industry in
Macedonia, International Scientific Conference – Wood Technology and Product Design, Ohrid:
(in press).
MELOSKA, Z., PETROVSKA, I. (2012): International Trade in Wood Sawn from Republic of
Macedonia, Proceedings, International Scientific Conference – Wood and Furniture Industry in
Times of Change – New Trends and Challenges, Trnava: pp. 148 – 154.
MELOSKA, Z., PETROVSKA, I., ANAKIEV, B. (2011): Current Conditions and Strategies for Export
Strategies in the Republic of Macedonia, Proceedings, International Scientific Conference –
Development Trends in Economics and Menagement in Wood Processing and Furniture
Manufacturing, Kozina, Slovenia: pp. 107 – 115.
STANKEVIK SHUMANSKA, M. (2012): Employment in the manufacture of wood and wood products
and furniture production in the Republic of Macedonia, Scientific, Professional and Information
Journal of Wood Science, Design and Technology - Wood, Design and Technology, Vol. 1,
Faculty of Design and Technologies of Furniture and Interior – Skopje: pp. 24-28.
STATE STATISTICAL OFFICE OF REPUBLIC OF MACEDONIA, Publications.
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Constructions of the Energy-saving Wooden Houses
and its Advantages on the Example of Polish Construction
STASIAK-BETLEJEWSKA Renataa*
a
Institute of Production Engineering, Faculty of Management, Czestochowa University of Technology,
Częstochowa, Poland
*
Abstract – Contemporary construction, in addition to modern solutions in the field of building
architecture, pay particular attention to applied construction materials, which have a great influence on
the stability and quality of the building. One of the most well-known materials in the world currently
used in residential construction is wood, which is used for the skeletal wooden constructions, as well
as energy-saving construction of prefabricated houses. This paper presents today's most popular
solutions for wooden construction used in energy-efficient homes in the Polish construction industry,
which are also covered by patent protection due to the nature of the solution. The main object of the
analysis is both characteristics of wood as a building material, as well as the advantages of timber
frame constructions, which also affect the comfort of house users.
wood / construction/ construction materials / wooden frames / wooden prefabricated elements
1. INTRODUCTION
The construction is a field of technical activity which includes: designing and all the
techniques and technologies of building home constructions, its maintenance and dismantling.
Depending on the materials used in construction there are: wood, brick, stone, concrete and
steel. The buildings consist of a plurality of elements, each of which has a particular function
and are made of materials with appropriate properties and quality. Construction materials are
required above all to be durable (depending on which security of the construction) and
hygiene (or lack of harmful effects on health and the environment). Properties of construction
materials shall meet the requirements of the relevant standards and technical approvals. The
construction works must comply with mostly basic requirements that are designed to
eliminate hazards to life, health and property of users and the environment and relate
primarily to: the construction safety, the fire safety, the usage safety, adequate conditions of
hygiene and health, and environmental protection (in the production of building materials, its
use and after the so-called technical life), protection against noise and vibration, energy
savings in the building and appropriate thermal insulation baffles. Compliance with these
requirements is dependent on, inter alia, the use of carefully selected materials and quality
construction.
Building materials used in the construction process are sorted according to various
criteria: method of obtaining (natural and industrial), the type of material that are made of,
disposition of the material, as well as the criterion of the degree of materials processing or
materials applying in the performance of the building individual elements. In the selection of
a building material in terms of its quality, physical and chemical properties there are crucial
factors such as: density, porosity, humidity, water absorption, moisture absorption, capillarity,
permeability, water vapour permeability, infiltration, thermal expansion, thermal conductivity,
heat capacity, resistance to freezing, shrinkage, corrosion resistance, fire resistance. The other
features of this type include, among others: sound absorption, adhesion or bonding ability.
The essential characteristics of construction materials are also mechanical properties such as:
durability, elasticity, plasticity, creep, relaxation, ductility, fragility, hardness, abrasion
resistance and impact resistance.
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Wood is a natural construction material (due to the origin and type of material). It is the
oldest building material, which is obtained from coniferous trees (pine, spruce, fir) and
hardwood (oak, ash, beech, elm, alder, birch and hornbeam). Technical properties of wood
depend on its anatomical and chemical structure. Due to the porous structure, wood has high
strength at low density (relative strength of wood is equal strength of the steel), has low
thermal and sound conductivity. Mentioned feature constitutes technical value of any wood
materials.
Thermal properties are the advantage of the wood construction, because wood is the best
the heat insulator. It also has high levels of specific heat indicators. This indicators group for
wood is significantly higher than for many plastics, almost twice then at brick and clay, the
stone and concrete, and more than four times than that of iron and steel.
The advantage of the wood construction is its easiness of its processing. Wood defects
include such factors as: a high hygroscopicity, swelling, shrinkage and cracking of wood and
its flammability and low stability. The physical characteristics and mechanical properties of
wood are different depending on its origin (hardwood, softwood), humidity and the analysed
section (laterally or along the grain). Physical and mechanical properties of wood affect the
possibilities of its use in construction.
The wood materials used in the construction industry are in the form of round wood
(from which comes sawn wood used for the manufacture of building products) and woodbased materials (veneer, block board, chipboard, fibreboard, wood panels, flooring, shingles).
One of the more popular wood-based materials currently used in the construction industry is:
a solid wood construction in the spliced systems, wooden structures systems and glued
laminated timber. Glued laminated plates are solid, consisting of cross-laid layers of wood
material. The use of laminated wood provides a very good sound insulation and meets all the
requirements for the fire safety.
1.1. Requirements for wooden constructions
Wood used in the construction should have moisture content in the range 18-19 %. It is
understood that during construction process, usually lasting several weeks, wood dries in
about 14 % for maximum strength, dimensional stability and do not cause warping of the
building construction elements. The same applies to solar, summer weather. In the autumn
and winter periods, a wood may increase its moisture content to 20-22 %.
Technologies related to the construction of both timber frame and prefabricated elements
used in the energy-efficient houses construction also impose requirements for systems and
components for the mechanical wood processing. It is required, that components should be
four-side planed. Such treatment not only provides dimensional stability, shortens time of the
building construction process, and decrease the labour costs. A four-side planning increases
the resistance of the wooden building structure against the fire.
The wood should be dried in the drying chamber to decrease of insect threat. Studies
conducted in the United States have shown that drying at high temperatures (around 60 °C)
deprives the timber of all natural substances, which could be a breeding ground for pests of
wood. The most serious and most common mistake in the case of the constructions carried out
in the light wood-frame technology is the use of wet wood and not planed. Such timber has a
negative impact not only structural strength, but also reduces the durability of the building.
Examples of the risks posed by the use of wet wood for the construction of the building:
− reducing the structural strength, wood of a tree freshly cut (with a moisture content greater
than 30 %) has a flexural strength of about 60-75 % less than wood with a moisture content
below 18 %,
− rapid destruction of timber, closed in the wall and not being able to quickly dry, wood is
brewing and exposure to blue stain, mold and fungi,
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−
destruction of the thermal insulation of external walls (moisture coming from the wood
penetrates the insulation layer by reducing its insulating properties),
− cracking of plasterboard walls and ceilings, wooden parts shrink and twist during drying
process.
1.2. The basis of the construction selection
Selection of building materials, in addition to physical, physical-chemical and mechanical
properties, also includes architectural requirements and economic reasons. In general, factors
determining the construction selection are following: the investor’s needs, type of coverage,
bandwidth, load type, quality of material, connections’ types, chemical factors, architectural
requirements, economic factors, and type of manufacturing, fabrication, and construction
operating conditions.
Architectural requirements are related to architectural forms, which are affected by such
factors as: the room assignment, lighting, ventilation, requirements for visibility or invisibility
of the construction. Economic factors are associated closely with the construction typicality,
type and level of performance and prefabrication. Cost performance in industrial design and
their installation on the construction place are lower in comparison to the cost of the
construction made directly in the construction place. The relatively lower cost is achieved by
performing a typical industrial structures and particularly suitable for prefabrication. In
addition, wooden structures are often chosen because of the possibility of obtaining more
living space than at home with the same conditions, but the brick one. Wooden house with
floor area of about 10 % smaller than a brick house can get the same living space.
Wooden structures have become more popular with investors, architects and construction
companies because of the energy efficiency of wood, and thus its environmentally friendly
nature. It was calculated, that the wooden construction of a timber wall with a height of 3 m
and 30 m in length, consumes 3.5 times less energy and 20 times less water than the concrete
and steel construction production. Wooden structures are also chosen because of the low
coefficient of expansion due to temperature changes, which means that the deformation of the
wood in the case of temperature increase is small (factor determining the size of losses in case
of fire).
2. THE IDEA OF ENERGY-SAVING WOODEN HOUSE
The idea of the energy efficiency improvement is one of the priorities of the European
Union policy, which covered all industry sectors, including the construction industry. It
should be emphasized, that the construction and real estate sectors are responsible for
approximately 40 % of the total energy consumption, approximately 30 % of the CO2
emissions and 40 % of the waste. To ensure a long term durability in the reduction of
environmental impact, we do not only have to reduce energy consumption in new building
constructions, we also need to ensure the LCA perspective and that future projects are carried
out in line with these objectives. That’s why energy saving idea was introduced into
construction sector.
Monitoring the progress and effects of European Union Directive implementation on the
Energy Performance of Buildings Directive (EPBD) in 2006 and noticing inadequacy of the
original solutions, the European Parliament in 2010 adopted changes to help improve the
energy efficiency standard of new and existing buildings. Technologies currently applied in
the construction industry have a strong orientation to the use of energy-efficient solutions for
applied materials, as well as constructions that will ensure future savings in the building
utilization. Both the European Union action to improve energy efficiency and seek innovative
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WOOD IS GOOD
solutions for architects and construction companies lead to make full use of the idea of
energy-efficient construction.
The energy-saving house is a house that consumes less than 15 kWh/ (m² • Year). This is
achieved by using a few special arrangements and meets certain conditions. The building
must have a very good thermal insulation, the walls of proper thickness, windows and exterior
doors with excellent thermal properties. There is also important tightness of the connections
between the different parts of the building, in order to avoid thermal bridges. Architecture
requires a compact body. The energy is obtained from renewable sources such as heat pumps
and solar panels. The idea of the energy-saving house was presented in Figure 1.
Figure 1. The concept of the energy-saving house
The most clear indicator of the energy performance of the building's operating costs for
investor or the owner of the house are energy consumption, resulting from its energy, which is
actually the energy consumed in the heating, ventilation, cooling possible, hot water and
lighting facilities. Meeting these requirements can be ensured by the use of a wooden
construction of the building.
3. CHARACTERISTIC OF CONSTRUCTIONS SUPPORTING ENERGY-SAVINGS
Wooden constructions used in Poland are mostly in the lightweight skeletal construction.
They can be divided into: Canadian housing (also known as the American), Swedish and
German. The different types of frame structures differ from each other thicknesses of certain
elements.
A characteristic feature of this building type is light skeleton made of wood. Foundations,
wall posts, beams and elements of the roof structure should have the same thickness, and the
width is dependent on the destination of a particular item. Stratification in the exterior walls
on the inside of the building in a lightweight skeletal construction is as follows: plasterboard
(12.5 mm thickness), vapour barrier (vapour retarder), polyethylene foil with a thickness of
0.15 mm), wooden structure with a thickness of 140 mm filled with insulation, chipboard
moisture-resistant (12 mm thickness), polypropylene foil, facade cladding. The wooden
construction is a kind of frame, which is the housing for insulating materials (Figure 2). The
thermal insulation of houses based on the frame structure is not determined by the thickness
of the walls, but the quality of the insulation layer.
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WOOD IS GOOD
Figure 2. The wooden frame house construction
Another popular type of timber construction is log homes. Wood that is used for logs, it
must be dried in the drying chamber. This allows items to be resistant to deformation and its
dimensions do not change. They are also immune to fungus, mildew and pests.
A third type of wood construction is energy efficient prefabricated wooden structure,
which will be characterized in the following part of the elaboration.
3.1. Characteristics of prefabricated wooden house technology
Prefabrication involves preparation of the various components (prefabricated) of the
building on the production floor. Prefabricated houses are made on the basis of the wooden
framing, after which it resets the consecutive components (panels), which creates a complete
home design. Ready components are assembled on-site construction of the house.
Prefabricated wooden constructions are made in the form of modules that are produced
by factories and later transported to the construction place. Technology of prefabricated
houses was widely used for the first time in Scandinavian countries. “Scandinavian houses”,
“Canadian wood-frame houses” or “Finnish houses” - it's all cheap houses that have passed
quality tests in much more difficult conditions than in Poland.
The walls of prefabricated wooden houses have skeletal structure (Figure 3). The space
between structural elements is filled with insulating material, which also plays the role of
thermal and acoustic insulation. The outer wall sheathing is OSB, secured by the windproof
membrane. The facade is made of profiled boards, secured by fire-resistance, fungicides and
insecticides. Cladding boards can be stacked horizontally, vertically or in a combination of
these positions. The colour of the facade paint coatings is selected according to customer
requirements. The outside walls are covered with chipboard covered with vapour foil and
finished with plasterboard or cement-fibres. The module technology ensures the appropriate
air exchange. Lightweight construction is very durable. The material which forms the walls,
ceiling and roof are prepared from a pine wood with class II or III.
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WOOD IS GOOD
Figure 3. The prefabricated module used as the energy-saving wooden construction
(Tadeks Fertighaus, Poland)
3.2. Specific solutions supporting energy-saving wooden house idea
The other type of prefabricated wooden construction is wooden element consist of
wooden boards only (Figure 4, element 1). The wooden boards as single items-wooden layers
(Figure 4, element 2), that are connected with applying of treenails arranged in a similar way
as the chessboard (Figure 4, element 4). There is also a version with empty spaces between
wooden boards to support energy-saving properties (Figure 4, elements 3a, 3b, 3c, 3d).
Figure 4. The prefabricated layered wooden element applied
in the energy-saving wooden construction
(invention of Thoma Erwin, St. Johann/Pongau, Austria, 1998, A1205/98 used in Poland)
The analysed wooden construction supports energy saving properties in different ways by
using: treenail and avoiding using nails (which can be thermal bridges), avoiding bonding
elements that requires chemical substances (environmentally friendly solution) and supporting
construction durability.
The other solutions concern the connection of wooden modular elements (Figure 5). In
order to simplify the module wooden constructions, in 1999, a building module was
elaborated. It constitutes a part of the shell wall, which are cross-linked support bars with at
least one spacer linker containing connecting of output beyond the lateral plane and lateral
posts for the series connection of adjacent modules. Pivot joints are used for connecting
neighbouring modules. The spacers are attached to the fittings carrier bars from their outer
sides or in the middle, preferably centrally, along the through-drilled holes. Lightweight and
simple design of the module allows the construction for efficient but stable skeletal material
and load-bearing walls and partitions of buildings using the building for a variety of building
materials.
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WOOD IS GOOD
Figure 5. The wooden building module (invention of Muszynski Arkadiusz, PL, WUP 09/07)
Therma-TEC PANELS are designed to the latest and modern standard of BS EN 1995-11:2004 Eurocode 5 (which is now in force parallel with old BS 5268-2:2002). Therma-TEC
PANELS were most probably the first in the UK to use spaced column designs as framing
members, thereby reducing and minimizing the problems of thermal bridging caused by
traditional solid stud members. Panels are designed to the Eurocode 5 standard within
European Union regulations. Clear space between shafts and gussets is another unique
property of Therma-TEC PANELS allowing the designers to hide all services in the panel
without disturbing structural elements. Even big services, such as 110 mm soil pipes or 200
mm ventilation ducts, can easily be accommodated in the panel leaving enough space for
insulation to reduce thermal bridges (Figure 6).
Figure 6. The innovative wooden frame house construction (Timber-TEC)
4. CONCLUSION
Analysis of chosen constructions applied in Polish energy-saving wooden construction is
environmentally friendly during the whole design process. Those building solutions are
characterized mostly with reducing thermal bridging effect reached by applying only wooden
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connections of wooden elements in the entire construction. Presented systems are driving
value of heat escape down to approximately 5 % of the wall area.
Analysed solutions are environmentally friendly because of the reducing of the amount of
applied wood and possibility to recycling materials wasted in the result of building.
The wooden constructions in all cases are excellent thermal performance because of
additional space gained for insulation. Typical U-value of panel element using fiberglass is in
the range: 0.13÷0.15 W/m2K. Reduction of total wall thickness as a result of isolation and
connection of the superstructure in one component causes economical savings as well such as:
material cost savings, reduce costs and significantly accelerates the implementation of
projects.
Acknowledgements: Research findings were elaborated within Visegrad Small Grant project
No 11310223 called “WoodEMA. Visegrad innovations”.
5. REFERENCES
BIČANIĆ, K.; JELAČIĆ D.; GAŠPARIĆ, V.; CAREV-LAŠKARIN, V.; KOCBEK-NIŽETIĆ, M. (2010):
Identitet poduzeća u preradi drva i proizvodnji namještaja Republike Hrvatske. Drvna Industrija
60 (3): pp. 145-153.
THÖRNQVIST, T. (2009): Wooden Ecobuildings – energy efficiency in LCA percepctive. School of
Technology and Design. Reports No 61. Växjö university. Sweden.
PATENT No. PL 167079, Iwanaszko Krzysztof, Słowiński Tadeusz, Presz Krzysztof, Poland,
06.08.1991
PATENT No. EP 0214088
PATENT No. EP 0744507
Invention of Thoma Erwin, St. Johann/Pongau, Austria, 1998, A1205/98 used in Poland.
Invention of Muszynski Arkadiusz, PL, WUP 09/07.
Timber-TEC, the right of Maciej Winiarczyk trading as Timber-TEC to be identified as the author of
Therma-TEC PANEL has been asserted in accordance with the Copyright, Designs and Patents
Act 1988.
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Microclimatic Conditions for Healthy Sleep and Rest – Influenced by
Science, Psychology and Design
SVOBODA Jaroslava – TAUBER Jiřía*
a
Department of furniture, design and habitation, Mendel University in Brno, Czech Republic
*
Abstract – This paper deals with the issue of healthy sleep and rest in relation to the various
pollutions of an interior. The current residential environment is being increasingly polluted in varying
degrees with certain amounts of emitting substances such as VOCs. The aim of this paper is a possible
solution to the problem by ionization of the environment in order to achieve the best possible quality
of the environment. Emphasis is placed on the design of the negative-ions generator and its
appropriate placement in an interior.
ion / microclimate / emission / design
1. INTRODUCTION
The interior environment where people spend most of their time is being polluted with
various polluting substances. Some of the main air-polluting substances are volatile organic
compounds (VOCs) which are emitted, for example, by furniture (new furniture mainly),
carpets, curtains and other decorative elements in an interior. These VOCs are the cause of
diseases of civilization and therefore it is only natural to try to limit their negative impact on
human organism. One of the possible ways to reduce emitted VOCs in the air is to remove
them with negative atmospheric ions. And this method is explored in this paper.
2. ATMOSPHERIC IONS
The air which surrounds us both indoors and outdoors is being constantly more or less
ionized. This means that the air contains a certain amount of loose atmospheric ions. The
more polluted the air becomes, the higher amount of light ions, which are so desirable and
necessary to people, turn into medium and heavy ions and consequently vanish. People, who
are sensitive to weather changes, perceive the fluctuating concentration of ions in the air.
Some of the common reactions are headaches, joint aches, or even mood changes, disruptions
in sleep and overall tiredness.
Atmospheric ions are electrically charged molecules, parts of molecules or molecular
clusters, which come into existence through ionization of gaseous components of the
atmosphere. To ionize the air an ionizing energy is needed and the sources of such energy are
constantly working on the terrestrial surface. Therefore the natural air is continuously ionized.
There is no electrically neutral air in the nature and people are adapted for this condition in
the long term. A certain amount of atmospheric ions in the environment is necessary so that
people can feel at ease (Figure 1).
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Figure 1. The ionization of air diagram (Jokl)
2.1. The division of ions
Ions are divided based on their polarity and weight.
Division of ions based on polarity:
• Positive – represented by nitrogen ions in the nature
• Negative – represented by oxygen ions and water-vapour ions
This fact is due to the composition of atmosphere, which contains 78 % of nitrogen, 21 %
of oxygen and the rest – about 1 % - is composed of water vapour and other gaseous
substances. The process of ionization is constant (creation and expiration of ions) and each
cycle lasts approximately 10-6 of a second.
Division of ions based on weight:
• Light – clusters of 10 to 30 molecules of high motility gasses, with a lifespan of a
few seconds, which constantly come into existence. In terms of biological effect
on man, these are some of the most important ions.
• Medium – clusters of hundreds of molecules with a lifespan of a few hundred
hours.
• Heavy – clusters made out of as many as thousands of molecules, whose life
expectation reaches weeks, usually containing “condensing nucleus”, i.e. particles
of dust, smoke or fume. The heavier the condensing nucleus, the shorter the
lifespan of a heavy ion.
Based on the above described division we can conclude that, the more polluted the air is,
the larger amount of light ions, so needed by man, turn into medium and heavy ions, which
consequently terminates their existence. Thus the quality of the air is measurable by the
amount of light ions contained in it.
Such phenomenon is exploited when the air is being ionized artificially (with air ionizer),
by increasing the amount of ions in the air which absorb more pollution, turn into heavy ions
which sediment faster and as a result the air is being purified.
2.2. Expiration of ions
When two ions of opposite charges collide, they exchange electrons and become
electrically neutral particles, hence they expire. This process occurs in the air, on solid
surfaces and also within the interior and exterior environments of buildings.
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3. ARTIFICIAL IONIZATION OF AIR
Nowadays, various home air ionizers can be found on the market. These are so-called ion
generators, which produce either ions of both polarities, or they are constructed in such a way
that positive ions are captured inside the generator and only negative ions are released. Thus
the generator provides only those ions which are beneficial and required in terms of biological
effect on man. Such generators operate according to various principles.
The first group consists of corona discharge ionizers. Ions are emitted by a metallic
needle which is placed in such a way that allows easy dispersion of the created light negative
ions into the air. A metallic emitter requires occasional maintenance as the air pollution
smelts on its pike which then dulls and the production of ions decreases.
The second group consists of carbon fibre ionizers, which currently represent the latest
method for production of light negative ions. The emitter comprises fibbers made of clear
carbon. Such fibbers need no maintenance as they do not produce any pollutants during
permanent output.
4. SYSTEM FOR MONITORING THE IMPACT OF NEGATIVE IONS ON VOC
EMITTED BY PAINT
The ability of negative ions to decrease the amount of pollutants in the air was utilized
during particular experiments monitoring the impact of negative ions on concentration of
selected VOCs in surveyed air. Based on the results of the experiments a testing system was
constructed (Figure 2), which monitored using the following method. First the air inside the
testing system was polluted with a specific amount of selected paint or a thinner. Once
polluted, the environment was then exposed to the effect of negative ions emitted from their
source (Figure 3).The concentration of emitted negative ions can be measured by a special ion
meter. The degree of air pollution inside the testing system is measured by a gas
chromatograph which analyses the quality of the air immediately after pollution and then
again after the effect of the defined concentration of negative ions.
The testing system comprises the following individual devices and equipment (source of
negative ions, ion meter, ventilator, thermometer with moisture indicator, and pump with off
take tubes).
Figure 2. Testing system
Figure 3. Ionizer
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Based on the results of the experiments, we can conclude that ionizing the polluted
environment decreased the concentration of selected VOCs, namely ethyl acetate, benzene, 1methoxypropane-2-ol, toluene, hexanal, n-butyl acetate, ethyl benzene, m/p-xylene, and
styrene. Other compounds were identified in small amounts and their concentrations either
decreased insignificantly or remained the same after ionization. Nitrocellulose paint was used
to pollute the air (Figure 4).
Readings of the concentration of ions during individual stages of the monitoring inside
the testing system:
• Unpolluted environment without ionization: approx. 0 negative ions/cm3
• Unpolluted environment with ionization:
15000-17000 negative ions/cm3
• Polluted environment without ionization:
2700 positive ions/cm3
• Polluted environment after ionization:
7000 negative ions/cm3
Graphic representation of the decrease of VOCs
[µg.m-3]
5000
4000
after pollution
3000
after spontaneous decrease
after ionization – ionizer off
after ionization – ionizer on
2000
1000
0
after pollution
after spontaneous
decrease
after ionization
ionizer off
after ionization
ionizer on
Figure 4. Graphic representation of the decrease of VOCs from nitrocellulose paint
5. UTILIZING THE RESULTS IN PRACTICE
A good research is the one which can be utilized in our lives, for example in production,
or it can be appropriately applied within an interior. Therefore the benefit of this work
becomes apparent when, for instance, utilizing an ionizer within an interior in order to
increase the quality of the air by deployment of negative ions which consequently increases
the quality of our health.
In the particular project, an ionizer was built into the construction of a tester bed. By
utilizing the tester, quite specific conditions (microclimate) supporting healthy sleep and rest
were achieved. A tester bed has an effect of pleasant environment and provides intimate
space, which can affect our psychological tranquillity. The depicted version features tester as
a free floating unit which is not fixed to the construction of the bed. Thereby we are provided
with very airy and open space. The tester bed is not furnished with the old-style deluxe and
heavy curtains, rather it is dressed with pellucid and special textile of certain permeability
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which can be fitted to the bed in a number of ways, for example with Velcro. Depending on
the interior in which the bed is to be placed and individual customer requirements, the bed can
be equipped, apart from ionizer and air purifier, with a range of electrical accessories such as
special lighting, acoustic speakers, etc. The design of the bed is modern and the material used
is Makassar veneer with high gloss in combination with white high gloss (Figure 6).
It is necessary that the individual designs be understood from two viewpoints – design
psychology and health – which are both priority of this work. This claim can be supported by
one of the designs which were introduced at Mobitex – the international fair for furniture and
interior design in 2008 where it was awarded Grand Prix for advanced technology and
material (Figure 5).
Figure 5. The prototype bed with tester introduced at Mobitex in 2008
Figure 6. Tester bed with suspension canopy
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The below depicted bed (Figure 7) is based on a circular ground plan and with circular
shaped tester fitted directly above it. The tester opens through vertical axis. In this particular
design the tester is in the form of a circular frame above the bed. The frame comprises three
parts made, for example, of plastic monocoque. The rest of the sectors are formed with steel
bars and textile tightened between them. These textile sectors are guided by conductor rods
around the perimeter of the bed. When opened the textile draws together in a shirring. An air
purifier with ionizer, lights and speakers are fitted in the top part of the canopy (Figure 7).
Figure 7. Circular design with futuristic concept
6. CONCLUSION
The purpose of this paper was to point out the issue of healthy sleep and rest, which are
more than often affected by various microclimatic conditions. The above stated issue,
therefore, has been analysed from three different viewpoints – science, psychology and
design. The scientific findings acquired through the previously explained experiments and
applied in the design of the tester bed, which initiated a new design with additional functions,
with crucial impact on the mental state of man. Such facility is beneficial not only to people
with allergies or ill people, but also to healthy people, who appreciate the possibility to
regulate the quality of the air.
7. REFERENCES
BRUNECKY, P. (1998): Domiciologie, Brno: MZLU, ISBN 80-7157-307-8.
JOKL, M. (2002): Zdrave obytne a pracovni prostredi. [s.l.] : [s.n.], 2002.
LAJCIKOVA, A. (2007): Syndrom nemocnych budov, Kancelar, 10, c.2, s. 38-39.
SALTHAMMER, T.; WENSING, M. (2001): Emissionsprüfkammern und -zellen zur Charakterisierung
der Freisetzung flüchtiger organischer Verbindungen aus Produkten für den Innenraum. In
MORISKE, H.J. und TUROWSKI, E.: Handbuch für Bioklima und Lufthygiene, III-6.4.1,
ECOMED-Verlag, Landsberg.
SPENGLER, J.; Mccartny, F.; Samet, M. (2001): Indoor Air Quality Handbook, McGraw-Hill
Professional, ISBN 9780074455494.
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Possibilities of CNC Manufacturing with Regard to Furniture Design
ŠIMEK Milana*– KOŘENÝ Adama – DLAUHÝ Zdeněka – MIHAILOVIĆ Stefana
a
Faculty of Forestry and Wood Technology, Mendel University in Brno, Czech Republic
*
Abstract – The research deals with numerous possibilities for, and aspects of, CNC (Computer
Numerical Control) manufacturing in regard to industrial furniture design. The objective of this work
is the evaluation of certain parameters of CNC furniture production technology, more precisely the
parameters of CAM (Computer Aided Manufacturing) processing with respect to a given type of
furniture – a work chair, constructed as a flat pack product. Work chair was chosen because it
represents a complex, functional and purely industrial furniture design. Basic ergonomic data are
described in relation to working while seated, then the specific approach to flat pack furniture
construction optimized for CNC manufacturing is introduced, as well as some examples of work
chairs. Flat pack furniture is becoming more and more popular, especially for its economy and ease of
production, transport and stocking. The outcome of the present contribution is to collect knowledge
about CNC / CAM technology and options for CNC optimized furniture design, offering the
employment of CNC technology capacities, related innovations and better mechanical resistance of the
final product.
CNC / CAM / furniture / manufacturing / design / flat pack
1. INTRODUCTION
The most important innovation of the 19th century in the furniture industry was perhaps
the industrial wood bending, which is associated with the name of Michael Thonet. He came
up with the idea of saving shipping space, and transport knock-down chairs. His most popular
chairs, made of bent wood (Figure 1) were sent thanks to dismountability across the ocean in
a box with a minimum of unused space (Figure 2). The concept of furniture dismountability
was re-introduced by Ikea in the 50`s of 20th century, by the „Lovet“ table. Innovation of Ikea
was assembly by a final customer. Next step which is crucial is the introduction of computercontrolled machines, i.e. CNC machining technology. CNC machining technology has been
developed in the 40`s and 50`s of the 20 century in the United States. Main advantages of a
CNC technology are automation of the manufacturing process, high accuracy and speed of
processing, high reliability and versatility with low maintenance and exclusion of technology
breaks for new settings. On the other hand main disadvantages are higher purchasing and
operating costs, higher knowledge demands on the operator and lower production speed
compared to large series production of the various specialized machines (HIGLEY, 2002).
This historical development and different possibilities of CNC in comparison with
traditional machines allow us to develop furniture which can be specific in its construction
and technology. This type of furniture is manufactured and shaped directly with CNC,
construction is dismountable and no fittings are used. All advantages and disadvantages of
CNC technology mentioned above are true in general (RAO, 2010). But there are always some
conditions which have to be fulfilled to make given advantages strong or disadvantages weak.
Number of axis of CNC determines its possibility to operate in different planes (SMID, 2006).
Nesting (of machined parts) on the other hand supports strong aspect of CNC production –
economical material usage (ALBERT, 2006).
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Figure 1. and 2. Parts of disassembled chair No. 14 (left) and a transport box with its many parts
(right)
2. CAM/CAD SOFTWARE
The software used in the furniture industry can normally be put into three basic categories
which can more or less be used together. They are:
• Common modelling programs for volumetric or flat models, including, if desired, the
construction of macros for the furniture industry.
• Software exclusively for the creation of furniture and interiors
• Software created for running machinery – WOP (wood oriented programming
software)
Ordinary modelling programs and their connection to CAM systems: This type of
program offers universal solutions for preparing the production of any item including
furniture. These programs feature specialized modules for various classes of design work.
Their obvious advantage is that they make it possible to define any object with complete
freedom, and in combination with a CAM module, to precisely define machining operations,
trajectories, and a detailed production sequence. Considering the character of these programs,
they are not advantageous for common products in the furniture industry when objects are
produced first and only later identified. Defining ordinary furniture pieces is too slow with
these programs; they are vulnerable to error and they contain an insufficient quantity of
readable data about an object. Their universality, on the other hand, makes them advantageous
for the development of completely new procedures.
Specialized systems: These are characterized by a narrow focus on furniture. Then can be
based on volumetric modelling programs and delineate manufactured models – a less
advantageous way, requiring similar objects to be created repeatedly. Their second principle
rests on defining generic construction parameters, on the basis of which objects can then be
created. This narrow focus means it is possible to use a greater or lesser number of the
machines commonly used in the furniture industry. The capabilities of a system are usually
predetermined and the concrete type of system will dictate the possibilities for general
application. However, it is not normally possible to come up with entirely new and hitherto
unexplored processes, as it is with ordinary modelling programs. The advantage of these
specialized systems lies in the way they can be used in everyday production, where the
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number of usable processes for milling is limited, and so these programs offer a systemic
solution for production.
WOP Software: Machines for making furniture are equipped with these programs, which
permit the user to input information and control the basic functions of the machine. This
software facilitates working with ordinary macros such as drilling, milling, mortising, cutting,
control of specialized aggregates, and other possible operations. Software of this type is
usually specifically designed for each particular producer, or even particular machine, and
makes possible the simple control of all of the machine's functions. As noted by author XU
(2004), ISO code is characterized by problematic readability and non-adjustability during
production. WOP programs designed to control furniture-making machines do not normally
permit advanced definition or processing, and when permitted, this definition can sometimes
be too complicated. This software, at the same time, is not conceived for systemic solutions
and is thus used only by machine operators; these programs may contain individual
components common to all products that are prepared by technical office workers.
The above-mentioned systems can overlap or collaborate in various areas. It is
nevertheless clear that despite this overlap, a concrete product is really only designed for use
in one area. WOP – basic machining, Ordinary modeller – free design and hitherto untested
processes, specialized systems – fast and effective processing of a large quantity of
information. Table 1 gives more precise data for evaluating the chosen programs.
For a given project it is possible to use all three types of software. WOP software serves
to set production machines and is always indispensible for running them. It can be used for
the final adjustments of a program. An ordinary modelling program can serve for quick design
of a solution and for optimization of trajectories. Specialized software can secure production
by conventional means. In the case of a successful design and interest on the part of the end
user, a design can be created for implementing a process even in this specialized solution.
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3. FLAT PACK FURNITURE AND CNC TECHNOLOGY
Flat pack furniture is a kind of furniture produced and prepared with a view to fast and
simple assembly, otherwise known as RTA (ready-to-assemble). As the name indicates, flat
pack furniture is made directly from flat materials (sheet metal, wooden boards, even
cardboard). Its features are the most efficient possible use of materials, compact design, and
simple assembly. It can often be classified as environmentally-friendly as well. The advantage
of flat pack furniture (considering today's nomadic lifestyle and the struggle with cramped
spaces) is found in the fact that it can be easily disassembled and transported, is space
efficient, has a small number of components and is simple to assemble (without complicated
tools). At the same time, this type of furniture is a cheaper alternative to standard furniture.
In this age of technical progress, a whole range of technologies are available which can
be used to produce flat pack furniture. The most widely used are rapid manufacturing (rapid
prototyping, 3D print), CNC routers, laser cutting, water jet cutting and others. Each has its
own specific features and the form of the resulting product is directly dependent on the
specific technology used.
The construction of flat pack furniture is characterized by the fact that it normally does
not require the use of complicated tools, joining components, or glue. Most often its
construction is predicated on a combination of friction and pressure between surfaces, holding
the entire piece together. Flat pack furniture uses the principle of male/female joints or
slot/pin joints. The most frequently used joints are mortise and tenon joints, finger joints, and
dovetail joints. The choice of joint type will depend on the choice of material. The chosen
material, with its physical and mechanical properties, directly affects the construction and
thereby even the final appearance of the product.
3.1. Trends
A growing need has recently emerged to change the rigid, static shapes that are typical for
flat pack furniture into dynamic and more user-friendly-shaped products. Geometrically
shaped objects are being transformed into organic products characterized by elegant curves
and interesting patterns. The perforation of surfaces helps to achieve flexible properties and to
bend wooden boards in order to create various shapes (Figures 4, 5, 6). It is thus possible to
ensure not only ergonomic shaping but also the springing of a given product or its
components (chair seats). However, geometric shapes evolve as well, imitating natural shapes
in the form of crystal structures (Figure 8) or lightweight stylized insect-like shapes
(Figure 7).
Apart from the trends in the shapes of furniture, quite interesting services – portals that
offer the plans and data of products designed for production – have also emerged lately. One
only needs to choose a design, and the portal administrator will send the data in the form of
source code to the nearest factory (www.ponoko.com). Projects like Sketch Chair (Figure 3)
that allows the users to design their own chair, in the spirit of the flat pack philosophy, are
also interesting. The project is distributed as open-source software and is suitable for both
designers and the general public.
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Figure 3. SketchChair by Diatom Studio
(http://www.sketchchair.cc)
Figure 4. Andy Kem Breakplane Table
(www.seeartdesign.com/artists/andy-kem)
Figure 5. Spring Wood by Carolien Laro
(http://www.dezeen.com)
Figure 6. Perforation, Flexi
(http://www.woodworkingtalk.com)
Figure 7. Angled plywood chair by Emiliano
Gody (http://blog.lrytas.lt/interjeras)
Figure 8. Chair 23D by Gustav
Düsing(http://gustav-duesing.com)
4. ERGONOMICS
Experts from all over the world have agreed that the upright sitting posture is the ideal
one. In Figure 9, selected drawings illustrating “the right posture” are displayed (DK 1+2 and
S). The ISO and CEN drawings serve as a basis for international standardization and are used
to educate furniture designers. Although these postures look very satisfactorily on the picture,
it must be mentioned that hardly anybody can actually sit like that for a long time. This
upright sitting posture or right-angle posture is basically a short physical exercise that does
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not have anything in common with a real working posture. As is widely known, the human
body allows a large range of various postures. So why do standardization committees choose
a single sitting posture as a reference for their standards? This question is very important since
sitting is a dominant activity of our everyday life.
Figure 9. Furniture standardization – “the
right posture”
Figure 10. Leaning chair
4.1. Working positions
When sitting in the front posture, the body leans forward. The weight of the body that
rests on the chair seat moves forward, onto the tailbone and hamstrings. Some types of sitting
furniture, where the angle of the chair seat is adjustable, allow the front sitting posture with
the back upright which may be useful for some working activities. This posture helps
maintain the upright posture by tilting the pelvis forward. Students have always been very
inventive when it comes to finding alternative postures in order to avoid painful sitting. Their
sitting postures when trying to find less painful positions are definitely worth observing. This
may be the field where we will find out what sitting furniture is supposed to look like. Most
kids quickly discover that sitting on a chair is much more comfortable when the chair is
leaned forward, thus avoiding bending their backs (Figure 10).
A
Figure 11. Resting positions by J.J.Keegan
B
C
D
E
Figure 12. Sitting positions for work activities
In Figure 11, the back-resting position when e.g. lying on your side is displayed. C. Hip
joint at a 45˚ angle. This is the resting position of the hip joint when both front and back thigh
muscles are balance and the lumbar lordosis retains its natural concave bent.
When sitting in the position where the femur and the spine form an angle of 90˚ and the
body is leaned slightly back (Figure 12 A), the work area may be reached by:
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•
bending the spine in the lumbar region by approximately 20˚ which leads to back
rounding and more pressure on the vertebral discs B
• increasing the angle of knees by 20 ˚C while keeping the back straight. In this case
however, the chair seat puts pressure on the back thigh muscles, which is not ideal. For
a full effect, the chair seat must be leaned forward E. The height of the desk must be
raised so that the chair-to-desk ratio is approximately 58 cm to 86 cm (MANDAL,
1985).
Long-term comfortable sitting may be achieved by:
• Decreasing energy consumption
This may be achieved through proper body support. However, the influence of this
precaution is limited, because even energetically less demanding muscle activities may cause
the accumulation of local fatigue, leading to the quick development of overall fatigue.
• The possibility of changing positions
According to some opinions, the surface that fits the sitting parts of a human body is the
optimum sitting surface. The truth is that to sit on such a surface feels very comfortable but
after a while, the feel of discomfort and the urge to change the sitting position appear.
However, changing the position is impossible due to the shape of the sitting surface. An ideal
support for our body in a single position definitely isn’t the key to comfort. Variation is very
important (Figure 13). We like changing positions because it is completely unnatural for us to
remain in the very same position for a long time. Each body part has its favourite position. So
trying to define which position is the best for us is completely pointless. The best position is
always the next one. Even the best position recommended by the best expert becomes
uncomfortable after some time (OPSVIK, 2009).
Figure 13. Variations (sketch by PETER OPSVIK)
Comfortable sitting requires the ability of a user to change positions often using as little
energy as possible. The possibility of changing position while working supports the dynamics
of sitting, thus strengthening back and abdominal muscles. It decreases the occurrence of back
pain and helps increase overall conditioning. Overall satisfaction may thus be achieved. And
that’s why a work chair should allow a user not only to change positions, if necessary, but also
to inspire him to do so through its form, whether directly or indirectly.
5. DISCUSSION / CONCLUSION
The aim has been to present a concept of furniture design based on the connection of
technologies, recent advances in the field of the ergonomics of sitting, and parametric design.
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Parametric design currently represents what most industries are trying to achieve – not only
does it save resources, but it also increases competitive strength and stimulates innovation
(SONG – GAZO, 2013; ALAGIĆ, 2011). In the furniture industry and timber trade, this tendency
may be observed mainly in the field of education and innovation. This is due to the fact that
one of the specific features of parametric designs is usually innovative design that is not
accepted by every customer. And due also to the fact that furniture, unlike other industrial
products, doesn’t have such well-developed legislation dealing with the placement of new
products on the market, new products struggle to break into the market.
Acknowledgements: The authors thank the Internal Grant Agency (IGA) of Mendel
University in Brno, Faculty of Forestry and Wood Technology, project IGA 57/2013.
6. REFERENCES
ALAGIĆ, I. (2011): How to Achieve Excellence, Innovation and Quality in the Wood Processing
Industry in B&H, 7. Naučno-stručni skup sa međunarodnim učešćem ”KVALITET 2011”, Neum,
B&H, 1. – 4. June 2011.
ALBERT, A. (2006): Understanding CNC Routers, FP Innovations, Forintek, p. 105.
URL: http://www.solutionsforwood.ca/_docs/reports/UnderstandingCNCRouters.pdf
DIATOM STUDIO, (2012): Sketch Chair.
URL: http://www.sketchchair.cc
DÜSING, G. (2012): Chair 23D.
URL: http://gustav-duesing.com/chairsgallerie.html
GODY, E. (2009): Angled Plywood Chair.
URL: http://www.interior-and-design.com/ 2009/04/14/angled-plywood-chairs/
HIGLEY, J. B. (2002): CNC applications. Calumet., Purdue University, Indiana, Cited: 15. 5. 2013,
URL: http://technology.calumet.purdue.edu/met/mfet/275/
JPANICHELLA (2011): Perforation. Flexi,
URL: http://www.woodworkingtalk.com/f9/my-senior-capstone-cnc-flatpack-furniture-38190/
KEM, A. (2010): Breakplane Table.
URL: http:// www.seeartdesign.com/artists/andy-kem/
LARO, C. (2011): Spring Wood.
URL: http://www.dezeen.com/2011/01/05/spring-wood-by-carolien-laro
MANDAL, A.C. (1985): The Seated Man: Homo Sedens. Dafnia Publications, Copenhagen, ISBN 87982017-1-9.
OPSVIK, P. (2009): Rethinking Sitting. W.W. Norton & Company, New York, London, ISBN 978-0393 73288-97.
PONOKO (2013): The world easiest making system, Available at: https://www.ponoko.com/
RAO, P.N. (2010): Cad/Cam: Principles & Applications, Tata McGraw-Hill Education, ISBN 9780070681934, p. 784.
SMID, P. (2006): CNC programming techniques: an insider's guide to effective methods and
applications. New York : Industrial Press, 2006. ISBN: 978-0831131852.
SONG, M.; GAZO, R. (2013): Competitiveness of US Household and Office Furniture Industry,
International Journal of Economics and Management Engineering, Apr. 2013, Vol. 3 (2), pp. 4755.
XU, X.W. (2004): Striving for a total integration of CAD, CAPP, CAM and CNC, Robotics and
Computer-Integrated Manufacturing, Elsevier, 20, pp. 101–109.
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Influence of Moisture Content on the Strength of Welded Joints
ŽUPČIĆ Ivicaa*– GRBAC Ivicaa – BOGNER Andrijaa – ŽULJ Ivana – LJULJKA Borisa
a
Department for furniture and wood products, Faculty of forestry, University of Zagreb, Zagreb, Croatia
*
Abstract –Wood welding is a process which includes both chemical and physical reactions. Heat is
formed during friction, melting and softening of the structure of wood. When the melt cools, a firm
joint is formed. Dowels are welded to the surface using rotary welding techniques. This paper studies
the influence of moisture content on the substrate and the impact of the dowels on the shear strength of
welded joints. This study covered nine groups of samples with different moisture contents and parallel
and perpendicular orientations of fibres in the substrate and dowels. The best results were recorded for
the sample group (P8M8P) with 7.7 % moisture content in the substrate and dowel. The group of
samples with low moisture content (P4M8O) had the worst results, with 4.8 % to 7.7 % substrate and
dowel moisture content, respectively. It was concluded that the moisture content in the substrate is the
most important parameter for the quality of weld, while the moisture content of the dowel does not
play such an important role.
beech wood / wood welding / moisture content / dowel / strength / joints
1. INTRODUCTION
Welding of wood is a process which creates chemical and physical reactions, heat is
formed by friction which melts and softens the structure of wood, and a firm joint is formed
by cooling of the melt.
The welded samples with 12 % moisture content in wood contained moisture in two
different forms, i.e. bound water and constitutional water (ROWELL – LEVAN-GREEN, 2005).
Bound water or hydroscopic water is linked by hydrogen bonds between molecules of water
and hydroxyl groups in wood. Structural water constitutes the bonds of water molecules
formed by reactions of wood components at high temperatures. Water molecules (bound
water) are bound into polysaccharides with the smallest pure sizes and the largest content of
free molecular groups. These are mainly wood polyoses and amorphous cellulose
(SHAFIZADEX, 1963).
During rotational welding of the dowel into the hole, various methods are used to ensure
joint strength. Some of those methods include: the use of ethylene glycol (also known as a
plasticizer of lignin) and other compounds, welding warm (heated) dowel and dowel with low
moisture content (0 to 1 %) and drilling of multistage holes (at a certain depth a smaller
diameter hole is drilled) (KANAZAWA et al., 2005). The research is based on small tightness
during welding at a depth of 30 mm. Groove dowels made of commercial type of beech, 10
mm in diameter and 8 cm in length, are welded into a hole 9 mm in diameter with rotation
frequency of 1200 min-1. At a certain depth, dowel rotation is stopped, and the insertion
pressure is kept for a short period of time. Control samples with 12 % moisture content
reached an embedded force of 1894 N, while samples with dowel heated to 100 ºC and
moisture content of 1 % reached an embedded force of 2986 N. This increase in embedded
force, i.e. joint strength by a little over 36 % is certainly significant. For dowels that had a
cross cut top, the embedded force increase was 41 %.
GANNE-CHEDEVILLE et al. (2005) researched important parameters in rotational dowel
welding (assembling joining). GANNE-CHEDEVILLE also measured the moment during the
welding of a dowel into the base, (it was far below the dowel torsion moment) which enabled
an easy insertion of the dowel. Their research used beech groove dowels 10 mm in diameter
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WOOD IS GOOD
and welded with two rotation frequencies (1165 and 1515 min-1). The elements the dowel was
welded into were made of beech and pine wood with an 8 mm diameter hole. The research
results showed an increase in joint strength with reduced moisture content when higher
rotation frequency was used. The best results in terms of strength were obtained with 0 %
moisture content and rotation frequency of 1515 min-1. By reducing moisture content in the
dowel and at 1515 rpm, joint strength was considerably increased compared to rotation
frequency of 1165 rpm. The best result in embedded force was achieved by the combination
of rotation frequency of 1515 rpm, using dowel which was welded into beech base and had
0 % moisture content, heated to 80 ºC and not treated with ethylene glycol. Average
embedded force was 3184 N. Control samples were glued with PVA, and average embedded
force of the dowel was 3701 N.
Improvement in joint strength was achieved by heating the dowel at 100 ºC to moisture
content of 1.5 % (PIZZI et al., 2004). Then the heated dowel was welded into the base using
rotational method. The average embedded force of groove dowel with 9 mm in diameter,
welded at 30 mm depth with rotation frequency of 1200 min-1, equals 3134 N. Joint strength
was equal to that of dowels glued with PVA. However, using the welding method the strength
is achieved in a few minutes, while PVA takes 24 hours to show similar results.
Latitudinal joining of groove joints using linear vibration welding was researched by
OMRANI et al. (2009). In the course of linear vibration welding groove joints easily evaporate
water from the compound thus increasing the welding surface. The research results clearly
show that increased grooved surface did not increase the strength of the joint, but it was rather
decreased. This justifies the use of straight joints. The cause of decreased strength of groove
joints are cracks that appear in the wood. The water evaporating joint had an increase in
strength, but a statistically insignificant one. This confirms the thesis of water evaporation and
change in moisture content of the wood.
The two wooden elements glued together are expected to reach the required strength of
the whole structure. Moisture content in the wood has a high impact on the quality and the
strength of the joint. Depending on the technology or conditions of use, the moisture content
in the wood (for gluing) is between 8 and 14 %. Individual elements which are to be glued
together must have even moisture content. If it differs by more than 2 %, this can cause stress
in the joint. This stress can result in broken joints, without additional external stress (RIVER –
OKKONEN, 1991).
BINIEK AND SMARDZEWSKI (1987) also researched the influence of wood moisture
content on the strength of glued joints. Increasing wood moisture content from 11.6 % to
18.1 % reduces the joint strength by 20 %. With an increase of moisture content to 35 %, the
strength reduces to 75 %.
The aim of the research was to determine the influence of various levels of moisture
content in the base and dower on the strength of a welded joint. The optimum moisture
content in the base and dower is expected to be around 8 % (the same as with glued wood),
and higher or lower moisture content will not decrease the embedded force, i.e. the strength of
the joint.
2. MATERIALS AND WORK METHODS
2.1. Samples, welding parameters and moisture content
The study was conducted at the Faculty of Forestry of the University of Zagreb. Beech
samples with the dimensions of 200x30x30 mm were used for welding dowels vertically to
the fibre orientation with three holes pierced in each sample. The samples with a dowel
welded in the fibre orientation had three holes drilled in the front part with the dimensions of
30x30x64 mm. Upon welding, samples were cut vertically into two identical pieces. Average
168
WOOD IS GOOD
density (ρ0) of beech was 0.74 g/cm³ (min. 0.60 g/cm³, max. 0.85 g/cm³) determined pursuant
to the HRN ISO 3131: 1999 (Croatian standard for determination of wood density for the
purpose of examining physical and mechanical properties of wood). Average wood ring width
was 2.81 mm. Grooved dowels were 120 mm in length and welded into the pierce 20 mm
deep with the rotation frequency of 1520 min-1 (the same frequency was used for welding all
sample types). Average welding duration was 0.87 s with the tightness of 2.02 mm.
This study used three levels of moisture content: 4.86 %, 7.74 % and 14.55 %. Moisture
content was defined pursuant to the HRN ISO 3130: 1999 (Croatian standard for
determination of water content for the purpose of examining physical and mechanical
properties of wood).
The bases and dowels with lowered moisture content were first dried at the temperature
ranging from 103±2 °C to 0 % moisture content. The samples were then conditioned for 2
days and stored in a hermetically sealed receptacle (during the period of 25 days prior to
welding) containing silicates in order to get moisture content evenly distributed on the sample
and prevent it from further absorption of moisture and swelling. All the samples prepared in
this way reached the average moisture content of 4.86 % (min. 4.04 %, max. 5.69 %).
The preparation of bases and dowels with the average moisture content of 7.74 % (min.
6.79 %, max. 8.89 %) was carried out on the samples conditioned during the period of one
month in laboratory conditions (23±2 °C temperature and relative humidity of 50±5 %).
The preparation of samples with an increased moisture content of 14.55 % (min. 14.24 %,
max. 14.73 %) was carried out on the samples conditioned in the air-handling unit under the
temperature of 20 °C and relative humidity of 92 % and conditioning took place until
reaching the appropriate moisture content for the samples (approximately 15 days).
Figure 1. The sample used for measuring the embedded force for dowels welded vertically to the fibre
orientation
Figure 2. The sample sawn in order to show the joint used for measuring the embedded force for
dowels welded in the fibre orientation
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WOOD IS GOOD
Table 1. List of samples and their codes
Code
P4M4O
P8M8O
P14M14O
P4M8O
P8M4O
P4M4P
P8M8P
P4M8P
P8M4P
Description
Samples with a lowered moisture content of 4.8 % in the base and dowel, welded
vertically on the fibres
Samples with moisture content of 7.7 % both in the base and in the dowel, welded
Samples with an increased moisture content of 14.6 % in the base and dowel, welded
Samples with a lowered moisture content of 4.8 % in the base and a moisture content
of 7.7 % in the dowel, welded vertically on the fibres
Samples with moisture content of 7.7 % in the base and a lowered moisture content
of 4.8 % in the dowel, welded vertically on the fibres
Samples with a lowered moisture content of 4 % both in the base and in the dowel,
welded in the fibre orientation
Samples with moisture content of 7.7 % in the base and the dowel, welded in the
fibre orientation
Samples with a lowered moisture content of 4.8 % in the base and a moisture content
of 7.7 % in the dowel, welded in the fibre orientation
Samples with moisture content of 7.7 % in the base and a lowered moisture content
of 4.8 % in the dowel, welded in the fibre orientation
2.2. Test method
After welding, the samples were conditioned for 20 days (23 °C temperature, relative
humidity of 50 %) and the measurements of the embedded force were initiated on a universal
mechanical testing machine with testing time shift of 5 mm/min. Computers were used for
measuring force and lag guaranteeing accuracy and preciseness of all values measured. For
the purpose of this study 270 samples were welded whereas 242 correctly welded samples
without any cracks were used for further study. Cracks and breaks appeared on 28 samples
which, consequently, could not have been used for further study.
The results of this study are presented in Table 2 and Figure 3. The study results indicate
that the strongest embedded force is linked with the samples with a moisture content of 7.7 %
in the base and 4.8 % (P8M4P) in the dowel as well as the samples with a moisture content of
7.7 % (P8M8P) in the base and the dowel. For both sample groups the dowel was welded in
the fibre orientation. When a dowel was welded vertically to the fibres the best results were
obtained for samples with a moisture content of 4.8 % (P4M4O) in both the base and the
dowel. The poorest results are linked to samples with moisture content of 4.8 % in the base
and moisture content of 7.7 % in the dowel.
Study results do not match the results obtained by GANNE – CHEDEVILLE et al. in 2005.
The results obtained in their research indicated higher values for the embedded force in
dowels with 0 % moisture content welded in a beech base in comparison to those with a
moisture content of 12 %. The study conveyed by KANAZAWA et al. (2005) also indicates an
increase of embedded force for dried dowels with the moisture content of 1 % in relation to
the control samples (dowels) with a moisture content of 12 %. The reason for the variation in
the distribution of study results is linked to the fact that different welding factors were
applied. Duration of the welding process and rotation frequency are among the most
important welding factors and they considerably reflect on the strength of a joint. Moisture
content also influences the strength of a joint but in the scope of the study considerably less
than the main welding factors (welding duration, rotation frequency, pierce and welding
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WOOD IS GOOD
depth). It is presumable that the welding of samples with the moisture content of 15 % up to
the saturation point of fibres would lead to the decreased strength of a joint.
Wood heating (wood was dried in a drying oven under the temperature of 103±2 °C)
leads to chemical reactions linked to the main wood components (lignin, wood polyoses and
even celluloses). MAMOŇOVÁ et al. (2002) studied microscopic changes in breech structure
after treating the samples in the water boiling from 100 to 140 ºC. Their study results indicate
condensation of lignin and decomposition of wood polyoses. Lignin penetrates (migrates)
through a cell’s membrane at 100 ºC and 10 minutes of treatment forming a drop-like
structure in a cell’s lumen. These microscopic alternations are followed by chemical reactions
in the main wood components. The analysis of hydrolysates indicates reactions linked with
the dissolution of acid components at the temperature of 100 ºC. Their concentration increases
with increased temperature and duration of a treatment. The analysis of saccharides confirms
the stability of my-contact at the temperature ranging from 100 to 110 ºC, and
depolymerisation starts at the temperature higher than 140 ºC. Non-crystallized cellulosic
components are present in small quantities under the temperature of 100 ºC. All these changes
have a significant impact on the welding process and the strength of welded joints.
The objective of this study was to investigate the possibility of welding samples with
various moisture contents. Researched ranges moisture content in the wood that can be found
in practice. Since those are relatively small ranges, this study should certainly extend to
welding wood with higher moisture content and lower so we can assume that the distribution
of embedded force was divided differently. The results of this study indicate that the entire
scope of various moisture contents under the survey proved to be optimal for welding.
This study used the optimal welding parameters since the research results and the insight
in the present scientific data (ŽUPČIĆ et al., 2010) indicates that the embedded force (strength
of a welded joint) reached the maximal values with the tightness ranging from 2 to 2.6 mm.
These values are at the same time optimal tightness for the rotational welding of a dowel
during the period of 0.8 and with the rotation frequency of 1520 min-1 (ŽUPČIĆ, 2010; ŽUPČIĆ
et al., 2011). According to PIZZI et al. (2003), the optimal tightness is 2 mm since any
increase or decrease of tightness results in a decrease of embedded force (with the rotation
frequency of 1200 min-1).
Table 2. Descriptive statistics of the results obtained for embedded force in relation to moisture
content and welding orientation
Sample
code
P4M4O
P8M8O
P14M14O
P4M8O
P8M4O
P4M4P
P8M8P
P4M8P
P8M4P
All
groups
Arithmetic mean
of embedded
force
(N)
5020.7
4623.0
4322.1
2563.1
4689.7
4477.5
5271.4
3341.0
5356.9
Sample
number
29
30
28
29
29
21
29
20
27
Standard
deviation of
embedded force
(N)
489.7
366.7
428.4
444.8
393.7
428.6
522.2
726.8
478.0
Min.
embedded
force
(N)
3820.0
3740.0
3480.0
1680.0
3700.0
3820.0
4250.0
1240.0
4010.0
Max.
embedded
force
(N)
6170.0
5340.0
5320.0
3520.0
5310.0
5180.0
6080.0
4292.0
6040.0
4438.8
242
989.7
1240.0
6170.0
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WOOD IS GOOD
6000
5500
Embedded force (N)
5000
4500
4000
3500
3000
2500
2000
P4M4O
P14M14O
P8M4O
P8M8P
P8M4P
P8M8O
P4M8O
P4M4P
P4M8P
Mean
Mean±SE
Mean±1,96*SE
Code
Figure 3. Influence of moisture content on the base and dowel and welding orientation (in the same
direction and vertically to the fibre orientation in respect of the embedded force in rotational dowel
welding)
4. CONCLUSION
The study indicates that beech dowels can be successfully welded into a beech base in a
controlled environment with different values for moisture content (rotation frequency of 1520
min-1, welding time of 0.87 s and tightness of 2.02 mm).
The impact of moisture content on the strength of a joint is not univocally defined. For
dowels welded vertically to the fibre orientation, the embedded force is less powerful
(statistically relevant) with an increase in moisture content of 4.8 to 14.6 %. For dowels
welded in parallel with the fibre orientation, the results indicate stronger embedded force
(statistically relevant) with an increase in moisture content of 4.8 to 7.7 %.
The samples with variable moisture content in the base and in the dowel indicated
important variations (statistically relevant) for the strength of a joint (the same applies to
wood treated with adhesives). The embedded force increased with an increase in the moisture
content of the base ranging from 4.8 to 7.7 % and a decrease in the moisture content lf the
dowel ranging from 7.7 to 4.8 %. The moisture content in the base plays a very significant
role in relation to the moisture content in the dowel.
5. REFERENCES
BINIEK, P.; SMARDZEWSKI, J. (1987): Effect of simultaneous changes in several factors on the
strength of fork-tenoned joints. Przemysl Drzewny, 38 (11): pp. 6-8.
GANNE-CHEDEVILLE, C.; PIZZI, A.; THOMAS, A.; LEBAN, J. M.; BOCQUET, J. F.; DESPRES, A.;
MANSOURI, H. (2005): Parameter interactions in two-block welding and the wood nail concept
in wood dowel welding. J Adhesion Sci. Technol., 19 (13-14): pp. 1157-1174.
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WOOD IS GOOD
KANAZAWA, F.; PIZZI, A., PROPERZI, M.; DELMOTTE, L.; PICHELIN, F. (2005): Parameters
influencing wood-dowel welding by high-speed rotation. J. Adhesion Sci. Technol., 19 (12): pp.
1025-1038.
MAMONOVA, M.; LAUROVA, M.; NEMČKOVA, V. (2002): Analysis of structure of beech wood
subjected to hydrothermal treatment. Wood Structure and Properties, Zvolen, Slovakia, 51-55.
OMRANI, P.; MANSOURI, H. R.; PIZZI, A. (2009): Linear welding of grooved wood surface. Eur. J.
Wood Prod., 67 (4): pp. 479-481.
PIZZI, A.; PROPERZI, M.; LEBAN, J.M.; ZANETTI, M.; PICHELIN, F. (2003): Mechanically – induced
wood welding. Maderas. Cienca y tecnologia, 5 (2): pp. 101 - 106.
PIZZI. A.; LEBAN, J. M.; KANAZAWA, F., PROPERZI, M.; PICHELIN, F. (2004): Wood dowel bonding by
high-speed rotation welding. J. Adhesion Sci. Technol., 18 (11): pp. 1263-1278.
RIVER, B. H.; OKKONEN, E. A. (1991): Delamination of Edge-Glued Wood Panels: Moisture Effects.
Limited number of free copies. Madison, WI: U.S. Department of Agriculture, Forest Service,
Forest products Laboratory.
ROWELL, R. M.; LEVAN-GREEN, S. L. (2005): Thermal Properties in: Handbook of Wood Chemistry
and Wood Composites, CRC Press, Boca Raton, FL, pp. 121-138.
SHAFIZADEX, F. (1963): Acidic hydrolysis of glycoside bonds. Tappi, (46): 381-383.
ŽUPČIĆ, I. (2010): Čimbenici koji utječu na spajanje tokarenih bukovih elemenata tehnikom
zavarivanja. Disertacija, Sveučilište u Zagrebu, Šumarski fakultet, pp. 1-237.
ŽUPČIĆ, I.; BOGNER, A.; GRBAC, I.; LOZANČIĆ, I. (2010): New insights into rotation welding of beech
wood. International Conference, Wood is good – transfer of knowledge in practice as a way out
of the crisis. Innovawood, University of Zagreb, Faculty of Forestry, Croatia 15th October, pp.
147-152.
ŽUPČIĆ, I.; BOGNER, A.; GRBAC, I. (2011): Vrijeme trajanja zavarivanja kao važan čimbenik
zavarivanja bukovine. Drvna industrija, 62 (2): pp. 115-121.
HRN ISO 3130 (1999): hrvatska norma za određivanje sadržaja vode za ispitivanje fizikalnih i
mehaničkih svojstava drva.
HRN ISO 3131 (1999): hrvatska norma za određivanje gustoće drva za ispitivanje fizikalnih i
mehaničkih svojstava drva.
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WOOD IS GOOD
The Effects of Press Time and Press Pressure on Modulus of Rupture and
Modulus of Elasticity Properties of Oriented Strength Board (OSB)
Manufactured from Poplar Wood
YAPICI Fatiha*– ESEN Raşitb
b
a
Karabük University-Forestry Faculty-Department of Forest Industry Engineering Karabuk and Turkey
Karabük University-Technical Education Faculty-Department of Furniture and Decoration Education Karabuk
and Turkey
*
Abstract – This study was carried out to determine the effects of pres time and pres pressure on
modulus of rupture (MOR) and modulus of elasticity (MOE) properties of oriented strand board
(OSB). For this purpose, 80 mm long strands made of poplar wood bonded with phenol-formaldehyde
resin at (9 %) with three-layer cross-aligned OSBs. The strands used for the production of test panels
were made up 50 % of core layer and 50 % of outer layers. The panels were pressed for three different
press times, from 3, 6 to 9 minutes, using 30, 40 and 50 kg/cm2 bar pressure respectively, aimed for
density of 0.65 g/cm3.
oriented strand board / phenol-formaldehyde / MOR value / MOE value
1. INTRODUCTION
The decline of a high quality wood supply has led to an increased demand for wood
composite materials over the past forty years. The major advantage of wood composite
materials which are manufactured from unnused low quality wood and residues of other wood
sectors. The wood composite materials which are included panel products such as plywood,
particleboard, medium-density fiberboard, and oriented strandboard (OSB) (HU, 2000).
Oriented Strand Board (OSB) is an engineered structural wood panel. OSB is made by
processing small diameter, fast growing trees into thin strands which are bonded together
under heat and pressure with an exterior resin binder. OSB panels are used various
applications such as building construction, furniture, roofing and flooring (YAPICI et al.,
2009)
Some mechanical properties of OSB panels are equal the playwood panels used for
structure areas and the process of manufacturing OSB is comparatively cheaper than plywood
industrial, too. (BROCHMANN et al., 2004). OSB industry was developed by using low-density
hardwoods such as aspen, yellow-poplar, southern pine, lodge pole pine, jack pine, scotch
pine, and so on (MALONEY, 1996). Because of this, there are many studies in the literature
related to OSB panels.
Pressing operation is an extremely critical step in the OSB manufacturing process.
Pressing conditions depend on resin type and amount, board density; furnish moisture content
and thickness of the panels (BAŞTÜRK, 1999). HSU AND KRINCIC (1997) stated that the
internal bond and wet modulus of rupture were substantially increased, and the thickness
swelling was reduced as the platen temperature was increased from 223 °C to 232 °C.
The mechanical and physical properties of OSB panels are affected by many factors such
as raw materials type, adhesive type and ratio, press time and pressure. The most important
parameters affecting the properties of OSB are press pressure and press time. The
determination of effects of these factors on the physical and mechanical properties of panels is
very important for the manufacturing of OSBs. In this study, the aim is to evaluate the effects
of press time and press pressure on modulus of rupture and modulus of elasticity of OSB.
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WOOD IS GOOD
The poplar wood was used in the production of the (OSB). The strands dimension in
usage was approximately 80 mm long, 20 mm wide and 0.7 mm thick. Firstly, the wood
strands were dried until 3 % moisture content before adhesive was sprayed on them for three
minutes. Then, the adhesive material within 47 % liquid phenol- formaldehyde resin, was
applied in 9 percent ratios based on the weight of oven dry wood strands.
The press periods and press pressure were 3, 6 and 9 minutes under the 30-40 and 50
kg/cm2 press pressure, respectively. The shelling ratio was 50 % for core layer and 50 % for
face layer, and density of the boards was aimed at 0.67 g/cm3 density. OSB panels, which
were dimensioned as 56x56x1.2 cm were made for experiments, in the nine conditions. They
were 18 in total as two for each. Hand formed mats were pressed in a hydraulic press. These
panels were labeled from 1 to 6. All mats were pressed under automatically controlled
conditions at 195±2 ºC. After pressing, the boards were conditioned to constant weight at
65±5 % relative humidity and at a temperature of 20±2 ºC until they reached stable weight
(TS 642 1997). The density, moisture content, modulus of rupture and modulus of elasticity
values of OSBs were determined according to the related standards (TS-EN 323 1999; TS-EN
322 1999; TS EN 310 1999).
During the measurement of screw strength values were determined using Zwick/Roell
Z050 universal test device with capacity of 5000 kg and measurement capability of
0.01 Newton in accuracy. In testing, loading mechanism was operated with a velocity of
10 mm/min.
Data for each test was statistically analyzed. The analysis of variance (ANOVA) was
used (α<0.05) for testing significant difference between factors. When the ANOVA indicated
a significant difference among factors, the compared values were evaluated with the Duncan
test to identify which groups were significantly different from other groups.
3. RESULT, DISCUSSION AND CONCLUSION
The density (D) and moisture content (MC) values of OSBs were determined according
to the related standards. The average density and moisture content of panels were obtained as
0.67 g/cm3 and 7.4 %, respectively. It was seen that the aimed and acquired density and
moisture content values within the ranges as specified in the related standards. The average
and standard deviation of the values of the modulus of rupture and modulus of elasticity of
produced panels are shown in Table 1.
Table 1. Summary of the test results of the OSBs
Press Pressure
30
40
50
Press Time
3
6
9
3
6
9
3
6
9
MOE (N/mm2)
Mean
Std. Dev.
5973.81
352.40
6206.97
982.73
6280.95
216.64
5193.86
513.60
6791.21
688.11
5345.78
1170
6629.10
397.62
2980.22
481.50
2950.18
581.00
MOR(N/mm2)
Mean
Std. Dev.
27.35
2.56
47.17
3.49
45.08
2.60
20.71
2.15
38.50
1.46
36.11
1.21
33.47
3.11
35.96
4.80
31.10
4.02
It was found that the MOR and MOE values of the test panels varied between 20.71 –
47.17 N/mm2 and 2950.18-6791.21 N/mm2, respectively. The lowest value for MOR of
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WOOD IS GOOD
produced panels was 20.71 N/mm2 (40 kg/cm2 and 3 minutes press time). The variance
analysis of MOR and MOE based on manufacturing circumstances of test panels was done by
using one-way variance analysis (Table 2).
Source
Corrected Model
Intercept
Pressure
MOE
Time
(N/mm2)
Pressure*Time
Error
Total
Corrected Model
Intercept
Pressure
MOR
Time
(N/mm2)
Pressure*Time
Error
Total
Type III Sum of
Squares
85491126.81
1298849045.63
32711660.76
8687820.35
44091645.69
15882349.99
1400222522.42
2721.349
55295.93
544.92
1466.77
709.66
331.60
58348.88
Df
8
1
2
2
4
36
45
8
1
2
2
4
36
45
Mean Square
F Value
10686390.85
24.22
1298849045.63 2944.06
16355830.38
37.07
4343910.18
9.85
11022911.42
24.99
441176.39
340.17
55295.93
272.46
733.38
177.42
9.21
36.93
6003.17
29.58
79.62
19.26
Sig.
(p<0.5)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
According to the variance analysis, the effects of the both press time and press pressure
on the modulus of elasticity values were significant statistically. Duncan test results
conducted to determine the importance of the differences between the groups are given in
Table 3.
Press Pressure
Press Time
50
40
30
9
6
3
MOE
Mean
HG
4186.50
A
5776.95
B
6153.91
B
4858.97
A
5326.14
A
5932.26
B
MOR
Mean
33.51
31.77
39.87
37.43
40.54
27.18
HG
A
A
B
B
BC
A
It can be seen that the changed of MOE values were changed from 4186.50 N/mm2 to
6153.91 N/mm2 according to Duncan's test, they were also given the same and different
homogenous groups. In addition, MOR values were changed between 27.18 N/mm2 and
40.54 N/mm2, and they were given same and different homogenous groups.
In this study, effects of press pressure and press time which are very important factors on
the modulus of rupture (MOR) and modulus of elasticity (MOE). MOR and MOE values were
affected by changing these factors. It can stated that as the press time increased, the values of
modulus of rupture improved and without any impact on modulus of elasticity. But, It was
seen that as press pressure increased, the values of MOR and MOE decreased. It can said that
these values were decreased due to degrade of individual strand produced from poplar wood
that have low density properties by increasing press pressure.
177
WOOD IS GOOD
4. REFERENCES
BROCHMANN, J.; EDWARDSON, C.; SHMULSKY, R. (2004): Influence Of Resin Type And Flake
Thickness On Properties Of OSB. Forest Prod. J. 54 (3):51–5.
MALONEY, T.M. (1996) :The family of wood composite materials. Forest Prod. J. 46 (2): pp. 19-26.
BASTÜRK, M.A. (1999): Improvements of The Oriented Strand Board With Chitosan Treatments of
The Strands. Ph.D. Thesis, Syracuse, New York, USA.
HSU, W.E.; KIRINCIC, S. (1997): OSB Quality Enhancement And Cost Reduction. Proceedings
International Particleboard/Composite Material Symposium. W.S.U.: pp. 91-99.
PAO-JEN, (STEVE) H. (2000): Bending Stiffness Prediction For Oriented Strandboard By Classıcal
Laminatıon Theory. University Of Toronto, 1-2.
TS 642/ISO 554 (1997): Standard Atmospheres And /Or Testing; Specifications
TS-EN 323 (1999): Wood-Based Panels,-Determination Of Density, TSE, Ankara.
TS-EN 322 (1999): Wood-Based Panels,-Determination Of Moisture Content, TSE, Ankara
TS EN 310 (1999): Wood-Based Panels-Determination Of Modulus Of Elasticity And Of Bending
Strength, TSE, Ankara.
YAPICI, F.; GÜNDÜZ, G.; ÖZÇIFÇI, A.; LIKOS, E. (2009): Prediction of Screw and Nail Withdrawal
Strength on OSB (Oriented Strand Board) Panels With Fuzzy Classifier, Technology, 12 (3): pp.
167-174.
178
WOOD IS GOOD
The Effects of Cast-Polyamide on the Modulus of Rupture
and Modulus Elasticity of Oriented Strength Board (OSB) Manufactured
from Scotch Pine
YORUR Huseyina*– YAPICI Fatiha – ESEN Rasitb
a
b
Department of Forest Industry Engineering, Forestry Faculty, Karabuk University, Karabuk, Turkey.
Department of Furniture and Decoration Education, Technical Education Faculty, Karabuk University,
Karabuk, Turkey.
*
Abstract – This study was carried out to determine the effects of using cast-polyamide on modulus of
rupture (MOR) and modulus elasticity (MOE) of oriented strand board (OSB) which were produced in
four different conditions. Firstly, control panels were manufactured, and also OSB panels produced by
adding cast-polyamide with 20 % - 30 % ratio compare with weight of oven dry wood particle both
out layer and inner layer. Phenol formaldehyde was used at 6 % ratio. Strands were used to the
production of panels made up 50 % of core layer and 50 % of outer layers. Test panels were pressed in
6 min., 40 kg/cm2 press pressure and 185±3 °C press temperature by aiming for a target density of
0.67 g/cm3. The values of modulus of rupture and modulus elasticity were determined by using
according to related standard.
oriented Strand Board /MOR value / MOE value / cast-polyamide/ phenol-formaldehyde
1. INTRODUCTION
The major advantage of wood composite materials is that they can be manufactured from
unused low quality wood and residues of other wood sectors. The wood composite materials
are plywood, particleboard, medium-density fibreboard, and oriented strandboard (OSB) (HU,
2000).
ZHU et al. (2005) stated that OSB is made of thin strands of wood mainly from
commercially grown trees. The unsurpassed orientation of the flakes gives it relatively higher
mechanical properties in the direction of the flakes than in the transverse direction (ZHU et al.,
2005). OSB is an engineered wood product that is manufactured from wood particles known
as strands, after bonded together with waterproof resin under pressure and heat (BASTÜRK,
1999).
OSB panels are widely used in many applications of the wood construction industry. One
of the advantages of OSB is its equivalent mechanical properties and substantially lower cost
compared to structural ply wood (HOWARD, 2000). Low-density hardwoods such as aspen,
yellow-poplar, southern pine, lodge pole pine, jack pine, scots pine were used in the
beginning state of OSB industry (MALONEY, 1996). YAPICI (2008) stated that while increase
of adhesive ratio and press time, improve of modulus of rupture and modulus elasticity values
of OSB panels produced in three different adhesive ratio (3-4, 5-6 %), three different press
time (3-5 and 7 min.) and three different press pressure (35-40 and 45 kg/cm2).
In this study, the aim is to evaluate the effects of using cast-polyamide on modulus of
rupture and modulus of elasticity of OSB panels.
Scots Pine wood (Pinus sylvestris L.) was used in the production of the (OSB). The
strands dimension in usage was approximately 80 mm long, 20 mm wide and 0.7 mm thick.
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WOOD IS GOOD
First, the wood strands were dried to 3 % moisture content before adhesive was sprayed on
them for three minutes. The press conditions were applied on 6 minute press time under the
40 kg/cm2 press pressure, respectively. The shelling ratio was 50 % for core layer and 50 %
for face layer, and density of the boards was aimed at 670 kg/m3 density. OSB panels, which
were dimensioned as 56x56x1.2 cm, were made for experiments.
Totally, five OSB panels were produced such as control panels which were done by using
cast-polyamide and other panels. Control panels were made by applying adhesive material
without wax, a solid content of 47 % liquid phenol- formaldehyde resin, was applied in 6 %
ratios based on the weight of oven dry wood strands. The other panels was produced by
adding cast-polyamide with 20 % - 30 % ratio compared to weight of oven dry wood particle
both in outer layer and inner layer.
There were 10 in total as two for each group. Hand formed mats were pressed in a
hydraulic press. These panels were labelled from 1 to 5. All mats of panels were pressed
under automatically controlled conditions at 185±2 ºC. After pressing, the boards were
conditioned to constant weight at 65±5 % relative humidity and at a temperature of 20±2 ºC
until they reached stable weight (TS 642 1997). The density, moisture content, modulus of
rupture and modulus of elasticity values of OSBs were determined according to the related
standards (TS-EN 323 1999; TS-EN 322 1999; TS EN 310 1999).
Measurements of MOR and MOE values were determined using Zwick/Roell Z050
universal test device with capacity of 5000 kg and measurement capability of 0.01 N of
accuracy. In testing, loading mechanism was operated with a velocity of 6 mm/min.
Data for each test were statistically analysed. The analysis of simple variance analysis
was used (α<0.05) to test for significant differences between factors. When the ANOVA
indicated a significant difference among factors, the compared values were evaluated with the
Duncan test to identify which groups were significantly different from other groups.
3. RESULTS AND DISCUSSIONS
The density and moisture content values of OSBs were determined according to the
related standards. The average density and moisture content of panels were obtained as
670 kg/m3 and 6.9 %, respectively. The average and standard deviation values of the modulus
of rupture and modulus of elasticity of produced panels are shown in the Table 1.
Table 1. MOR and MOE values
Experimental conditions
0 (Control- non cast polyamide)
1 (Cast polyamide only core layers with 30 %)
2 (Cast polyamide only outer layers with 30 %)
3 (Cast polyamide only core layers with 20 %)
4 (Cast polyamide only outer layers with 20 %)
MOR (N/mm2)
Standard
Mean
Dev.
21.93
4.02
25.50
2.86
19.82
2.22
25.31
4.11
26.39
6.53
MOE (N/mm2)
Standard
Mean
Dev.
4277.08
800.95
4225.32
1432.19
3331.52
939.25
4934.93
1062.86
4940.61
969.88
MOR and MOE values were two of the most common tests in the OSBs. It was found
that the MOR and MOE values of the test panels varied between 19.82 – 26.39 N/mm2 and
3331.52 – 4940.61 N/mm2, respectively. The variance analysis of MOR and MOE based on
manufacturing conditions of test panels was done by using one-way variance analysis (Table
2).
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WOOD IS GOOD
Sum of Squares
186.77
445.02
631.80
Df
4
25
29
Mean Square
46.69
17.80
F- Value
2.62
Sig.level
0.05
According to the variance analysis, the effects of the cast-polyamide on the modulus of
elasticity values and modulus of rupture values were not statistically significant. Duncan test
results are given in Table 3.
MOR values
MOE values
Experiment conditions
2- Cast polyamide only outer layers with 30 %
0- Control- non cast polyamide
3- Cast polyamide only core layers with 20 %
1- Control- non cast polyamide
Mean
19.82
21.96
25.31
25.50
26.39
3331.52
4225.32
4277.08
4934.93
4940.61
HG
A
AB
B
B
B
A
AB
AB
B
B
It can be seen that the MOR values changed between 19.82 N/mm2 and 26.39 N/mm2
according to Duncan's test. panels number 1.3 and 5 was given the same homogenous groups.
In addition, MOE values changed between 3331.52 N/mm2 and 4940.61 N/mm2, and they
were put in the different homogenous groups.
4. CONCLUSION
In this study, the values of MOR and MOE were among the most important mechanical
features of oriented strand boards. Especially, it can be stated that if used cast-polyamide ratio
was increased, the modulus of rupture values of test panels improved on the test panels
produced by using cast-polyamide in core layer with 30 % and 20 %. The highest MOR value
was obtained from fourth samples as 26.39 N/mm2, the lowest values of this were obtained
from second samples as 19.82 N/mm2. Also, the results showed that the values of modulus of
elasticity changed between 3331.52 and 4940.61 N/mm2.
5. REFERENCES
BASTÜRK, M.A. (1999): Improvements of the Oriented Strand Board With Chitosan Treatments of
The Strands. Doctoral thesis, Syracuse, New York, USA.
HOWARD, J.L. (2000): U.S. Forest Products Annual Market Review and Prospects. FPL-RN-0278.
USDA Forest Serv., Forest Prod. Lab., Madison, WI.
MALONEY, T.M. (1996): The family of wood composite materials. Forest Prod. J. 46 (2): pp.19-26.
PAO-JEN, (Steve) H. (2000): Bending stiffness prediction for oriented strandboard by classıcal
laminatıon theory, University of Toronto, 1-2.
YAPICI, F. (2008): The effect of some production factors on the properties of OSB made from scots
pine (Pinus sylvestris L.) wood. Zonguldak Karaelmas University, Bartın, Turkey.
181
WOOD IS GOOD
ZHU, E.C.; GUAN, Z.W.; RODD, P.D.; POPE, D.J. (2005): Finite element modelling of OSB webbed
timber I-beams with interactions between openings. Advances in Engineering Software 36,
pp.797–805.
TS 642/ISO 554 (1997): Standard atmospheres and /or testing; Specifications
TS-EN 323 (1999): Wood-Based panels,-Determination of density, TSE, Ankara.
TS-EN 322 (1999): Wood-Based panels,-Determination of moisture content, TSE, Ankara
TS EN 310 (1999): Wood-Based panels-Determination of modulus of elasticity and of bending
strength, TSE, Ankara.
182

wood is good - user oriented material, technology

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