Quality control tools functioning in integrated management system in

Scientific Journals
Zeszyty Naukowe
Maritime University of Szczecin
Akademia Morska w Szczecinie
2011, 27(99) z. 1 pp. 92–97
2011, 27(99) z. 1 s. 92–97
Quality control tools functioning in integrated management
system in the automotive branch company. Case study
Narzędzia kontroli jakości funkcjonujące w zintegrowanym
systemie zarządzania w przedsiębiorstwie branży
motoryzacyjnej. Studium przypadku
Katarzyna Midor
Silesian University of Technology, Faculty of Organisation and Management
Institute of Production Engineering
Politechnika Śląska, Wydział Organizacji i Zarządzania, Instytut Inżynierii Produkcji
41-800 Zabrze, ul. Roosevelta 26, e-mail: [email protected]
Key words: Integrated Management System, methods and quality management tools, SPC, control cards
Abstract
The article focused on the role of quality control methods in designing and production processes, on the
example of the automotive company, in providing a product’s parameters in accordance with a client’s
requirements. Methods and tools used in a process of production, which are instruments controlling and
diagnosing quality during production, were analyzed. Much attention was paid to SPC methods that
statistically describe a production process.
Słowa kluczowe: Zintegrowany System Zarządzania, metody i narzędzia zarządzania jakością, SPC, karty
kontrolne
Abstrakt
W artykule zwrócono uwagę na rolę metod kontroli jakości w procesie projektowania i produkcji, na przykładzie przedsiębiorstwa branży motoryzacyjnej, w zapewnieniu parametrów wyrobu zgodnych z wymaganiami
klienta. Przeanalizowano zastosowanie metod i narzędzi w procesie produkcji, które są instrumentami nadzorowania i diagnozowania jakości podczas produkcji wyrobu. Zwrócono uwagę na metody SPC, które opisują
w sposób statystyczny proces produkcji.
Introduction
tion is a company’s aspiration for improving all
fields of activity and processes carried out in a firm
[1].
Implementing the requirements of quality
management systems, environment protection and
safety at work allow to achieve a lot of notable
benefits, among which one may count: using the
same methods of implementation, verifying,
approving and supervising documents, limiting the
amount of systemic documents in use. Thanks to
a possibility of taking into consideration, at the
same time, aspects of quality management, environment and safety at work, a uniform system of
documentation is introduced, achieving a high
Common market, fast growing competition, and
even more radical legal determinants, which develop in a direction of a bigger human life protection, health and natural environment, forced companies to take a comprehensive attitude towards
a company management issue. International Standards Organization ISO made an effort to meet
these requirements, establishing standards concerning the following aspects, quality management
system, environment management and management
system of safety at work. The aim of introducing
Integrated Management System into an organiza92
Scientific Journals 27(99) z. 1
Quality control tools functioning in integrated management system in the automotive branch company. Case study
quality standard that can ensure the increase of
a company’s competitiveness on the market,
limiting the costs of systems’ maintenance [2, 3].
Quality, treated as a priority goal in a company,
may be a key factor in the conditions of high competitiveness on the market. Quality management is
a collective effort of an organization that aims at
increasing quality and improving overall activity of
a corporation, in order to achieve optimal effects.
Quality ought to be a priority in a producer’s,
a supplier’s and a recipient’s activities. It should be
expected that a company’s activities were a process
of a constant creative learning, which serves to gain
skills of adjusting to every customer’s requirements, and to changing competitive surroundings
[4].
A very important factor, from the perspective
of ensuring a stable level of products’ quality in
a company, is implementing methods and quality
control tools, when used properly, through preventing the imperfection of a product’s life cycle on its
every stage. These methods and tools have a very
big influence on reducing losses and a company’s
costs efficiently. Using quality control tools enables
providing and confirming a product’s, or even
a whole production system conformity with the
guidelines and norms, which is an important information for a customer that a given product was
designed and produced in a way assuring a user’s
safety. It is significantly important in case of companies producing for automotive industry. Preventive activities bring more benefits than after the fact
ones, which are related with advertising costs,
selection or correcting activities [5].
Therefore, the author of this article pays attention to methods and quality control tools, used in
the company being analyzed, and to possible causes
of lack of compliance.
Bearing in mind the aim of increasing the efficiency of organization’s management, Integrated
Management System has been gradually implemented by the top management, which now includes:
 ISO/TS 16949:2002,
 ISO 14001:2004,
 PN-N-18001:2004,
 BS OHSAS 18001:2007.
Integrated Management System described in the
Book applies in all organizational sections, and
spreads throughout the company’s production:
steering transmissions; components (slats, ratchets,
and casings): for an internal production and corporate customers.
Apart from the Book of Integrated System, there
is also Company’s Perfection of Activities Plan that
includes complementing elements, which serve as
supporting tools in development and improving
processes, and achieving better results.
Company’s Perfection of Activities Plan includes:
 Business management,
 Products’ improvement,
 Quality improvement,
 Operating improvement, (LEAN),
 Cooperation with customers,
 Finance management,
 Personnel management,
 IT systems,
 Cooperation with suppliers.
The company’s policy, following the norms
ISO/TS 16949:2002, ISO 14001 and PN-N-18001,
was included in a document Management Rules and
announced to all workers. One of its key elements
is the responsibility for products and actions taken,
which is reflected in a slogan “Quality is me”. The
analysis of the company’s systemic documentation
points to the fact that the company uses a variety of
management instruments, which allow to develop
constantly and to increase the quality of the company’s products. However, the top management still
does not achieve a satisfactory low level of rejects
in the organization.
The characteristic of the analyzed
company1
The analyzed company is a concern delivering
products on the automotive market. It was founded
in 1972. Nowadays, the company produces steering
systems for Fiat Renault, Volkswagen, Mazda and
Ford, slat transmission gears with hydraulic support, slat transmissions for electric support system
“Column Drive” type, steering columns “Tube in
Tube” type, and components like casings, ratchets
and slats.
1
Quality control tools inside a company
Control in its wide perspective means: examining, measurement, assessment attempt, checking
or verification of a few or only one characteristic of
an analyzed product or a process. The results are
compared with a customer’s demands and requirements in order to verify, and to estimate if the accordance with the assumed level was achieved [6].
The analyzed company did not give a permission for
presenting its name, therefore, identification data will
not be given in the following article.
Zeszyty Naukowe 27(99) z. 1
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Katarzyna Midor
On every stage of a product’s life, quality control
takes different forms.
On the stage of parameters’ design, the methods
used aim at designing a product without defects
causing incorrect functioning during its operation.
The most common method in this phase of a product’s life cycle is FMEA or DOE.
FMEA analysis is used successfully in automotive companies on the initial stage of projecting
technological processes, on a construction stage of
a product, while starting a trial and also a serial
production. This method may also be used successfully to analyse a professional risk and to asses
environmental aspects inside a company, therefore,
it is a significant management instrument in
an organization, in which Integrated System of
Quality, Environment and Safety Management is
implemented.
FMEA method is used to identify potential
defects of a product or a process, and its causes.
A team conducting an analysis, by means of their
knowledge and experience, make a risk assessment
of a potential defect, inconsistency or mistakes; and
then they try to find their causes and predict possible consequences. Afterwards, the team implement
preventive and correction actions. After introducing
these actions, the analysis is conducted again, and
another risk assessment of a potential defect is
made. Thanks to FMEA analysis, actions are taken
inside a company in these sections where high risk
appears.
The outcome of a properly conducted FMEA
is planning efficient control and production process
supervision. A well prepared control plan is
a practical document shaping an overall view of
supervision of a product’s important characteristics
and its parameters, which influence a final
product’s quality in a production process. The
control plan includes: control method, criteria,
frequency, a sample’s size, a contractor, controlling
facilities, a goal, controlling procedure, a way of
registering and a way of reaction to deviation.
The most common method of controlling production processes’ parameters in an organization is
SPC, that is Statistical Process Control. This is
an instrument that may help to monitor efficiently if
a given process is statistically possible to control, in
other words, if it is predictable in its course. What
is more, it enables to verify disturbances, which
take place for special reasons, different from a natural variability of a process.
As part of SPC, X-R cards are used to control
a product’s and a process’s characteristics. They
use the laws of probability calculus or mathematical
statistics that allow to find unfavourable deviations
or trends in a process analyzed. A chart of a stable
process does not cross UCL and LCL limits, and
trends cannot be seen. If there are any signals of
inconsistency, another control is made, and the
following elements are analyzed: a size of sample,
frequency of control, measuring device, correctness
and a method of measurement registering. It is also
dependant on a product’s complexity and a production process, as well as on a company’s financial
possibilities, but most of all on a customer’s requirements and expectations.
To supervise and to make processes in a company stable, as part of SPC, different control cards
are used. A suitable control card is used to monitor
production, which depends on a method of taking
sample, a kind of a parameter measured, a number
of parameters controlled and a characteristic of
a process being controlled. In a company analyzed,
the most common control cards include [7]:
 single-track X card, with a numerical assessment
of a property;
 double-track X-R card, with a numerical assessment of a property, average value (X) and
gap (R);
 double-track X-S card, with a numerical assessment of a property, average value (X) and standard deviation (S);
 single-track p card, with alternative assessment,
a card of incompatible fraction units;
 single-track c card, with a gradual assessment,
a card of incompatibles.
The completion of a component’s quality
control in the analyzed company
Creating a product’s quality in the analyzed
company takes place on every stage of a product’s
life, starting with a concept and a project, through
designing production processes, distribution and
finishing with its use. While designing a product by
means of FMEA method, a recipient’s requirements
are converted into a specificity of a given product.
Not only financial limitations, but also organizational, technological and technical ones are taken
into considerations. Of big importance are designers’ experience and their knowledge. On this stage
a possibility to assess critical places is highly
important.
Control plans in a company, which are based
on FMEA analysis, are fundamental for activities
being part of TQ-X procedure. This procedure
describes very precisely a line of quality control
statistical techniques in a company, which are used
to verify a product’s and a process’s characteristics.
SPC enables a company to limit incompatibilities
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Scientific Journals 27(99) z. 1
Quality control tools functioning in integrated management system in the automotive branch company. Case study
on each stage of a process, supervising systematically a production process, maintaining a required
level of quality, allowing the process to be improved.
In the following article the use of SPC in a company will be presented on the example of a fragment of a serrated slat product – figure 1. The
points, which are determinants of a customer’s
requirements encompassed in a product’s specificity, are marked on figure 2. They refer to the tilt
angle of a serration line, and the length on grooves.
These two characteristics of a product are subject to
control, as they can significantly influence the final
quality of a produced component.
In Control Plan on Slat Line, on a workstation
teeth broaching, on a machine Pull Broach Varinelli
5056 Broach 90014 the following were included:
control characteristics, criteria, frequency, a sample’s size, a contractor, controlling devices, a goal,
control procedure, register method, as well as a way
of reaction to deviation. On account of this document’s complexity, it is not possible to present it in
the following article. A production process control
of a serrated slat starts with presenting OPDS. It is
a document confirming the first properly produced
item on a given post. A leader of a given manufacturing cell or an operator, having an appropriate
training, controls the parameters of the first item.
If he finds them correct, he gives this item to
a laboratory for further measurements.
Presenting a certificate of the first good item
is very important, as it prevents starting a mass
production of a product having incorrect parameters. OPDS is given not only after devises’ retooling for a new model of a product, but also after
repairs, maintenance staff interventions, serious
failures disturbing a process or stoppages. OPDS on
a Slat Line is conducted by an operator or a quality
controller with a frequency described in a Control
Plan, depending on a control procedure which is
subject to a characteristic’s control.
After starting a mass production of a Serrated
slat, X-R card is used in a company, in order to
monitor key parameters, such as: tilt angle of
a serration line and length on grooves. On figures 3
and 4 model X-R control cards are presented for
chosen parameters (these cards are presented fragmentarily on account of a possibility that the
company might be identified). The parameters that
directly influence a final quality of a product, or
Fig. 1. A product, a component – slat [8]
Rys. 1. Wyrób, komponent – listwa [8]
Fig. 2. A fragment of a serrated slat product [8]
Rys. 2. Wycinek z wyrobu listwy zębatej [8]
Fig. 3. X-R Card, measurement of tilt angle of a serration line [8]
Rys. 3. Karta X–R, pomiar kąta pochylenia linii uzębienia [8]
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Katarzyna Midor
Fig. 4. X-R Card, measurement of length on grooves [8]
Rys. 4. Karta X–R, pomiar długości na wyrębach [8]
significantly affect a further course of a production
process were controlled. It is possible to directly
influence on these parameters, thanks to steerable
factors in a process. Monitored features have
determined minimum tolerance limits (DLT), as
well as maximum tolerance limits (GLT) in the
range, in which their compliance or their lack
is marked, according to precisely defined requirements beforehand.
The sizes, that decide if the information gained
from these cards is credible, are: a constant size of
a sample, and its proper amount, a normal layout of
results, frequency, a regularity of sample taking,
initial adjustment of a machine, an operator’s diligence and knowledge and finally measuring device.
In the company analyzed, keeping X-R control
cards is based on regular sample taking, in defined
time intervals and given numbers, measuring the
value of an analyzed parameter (in this case length
on grooves and tilt angle of a serration line). It is
done by means of measuring the average value X
and the gap R in a sample, with a previous assumption that analyzed sizes have a normal layout.
When selecting a number of samples, the company is guided by statistical and economical criteria. The number of samples, for statistical reasons,
ranges between 3 and 12, in the case studied it is 5.
The frequency of taking a sample depends on
a function of a process’s stability. The more stable
a process, the longer an interval (frequency).
In both examples it is 1 item per 200.
In order to simplify the analysis of changes
taking place, the following factors are marked on
a control card: central lines which are to determine
a planned average value, and tolerance lines meaning requirements, which are set for a supervised
value.
Using control cards, which are part of SPC
method, is to minimise internal costs, as well as the
external ones, by turning towards a necessity of
eliminating rejects, failures. Moreover, it is a constant strive after perfection in a given task, in order
to eliminate continuous error correction and controlling the number of rejects.
Despite the use of a lot of methods and tools to
control and supervise quality in the analyzed company, the costs of rejects on a serrated slat production are high. The costs the company incurs on sorting for incompatible production, which cannot
be repaired, with reference to a whole company,
remains on the level of 0.43% of the sales income
in the last three quarters of the year 2010. It is far
too much, taking into consideration so high costs of
prevention means, such as using FMEA, OPDS or
SPC method.
Presented on figures 3 and 4 X-R cards show
that the process, despite small deviations, is stable.
There are no fluctuations, which could cause such
a level of rejects. As a consequence, it should be
considered what influences these costs.
The reasons for this state may be different. The
author suggests a necessity to analyse individual
elements of a control plan. The following factors
should be reconsidered: frequency of sample taking, quantity, the quality of a control tool. Attention
must paid to the fact that control is conducted by
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Quality control tools functioning in integrated management system in the automotive branch company. Case study
an operator very frequently, marking manually
measurement data on a control card. Although the
company aspires for a bigger involvement of all
employees, as it decides about quality improvement, not every worker has the same professional
competences or predispositions. Statistical techniques are not easy methods.
An individual training might be necessary –
fitted for a specific workstation, as well as verifying
methods of motivating employees. The questionnaire conducted by the author, among workers
filling in control cards, shows explicitly that data is
not marked with a proper care. The company’s
management ought to consider a necessity of
investing in a specific programme, which could
eliminate such a state of affairs. It is worth quoting
Y. Kondo “....in order to produce a product with
attracting quality that would increase the level of
a customer’s satisfaction, an employee should feel
satisfied with his work. And this is not possible
without the efforts made by the management staff
of a company...” [4].
ences significantly a strive to avoid situations in
which a final user’s safety could be in any way
endangered. Finding that a product is incompatible
with requirements may result in the cost of sorting
for rejects and work repair, if the incompatibility
will be detected inside a company. However, if
a faulty product leaves a company, the consequences are much more serious: a necessity to pay
a compensation to a customer, removing the results
of a failure in a recipient’s company, possible loss
of a company’s position on the market. In case of
a recipient being exposed to serious losses, a loss of
health or even a customer’s or other parties’ life the
result may mean being brought to justice. The presented situations can affect negatively a company’s
functioning, disturbing its financial stability, cause
the key customers’ withdrawal or ruin a company’s
image. As a result, a company may lose its economic basis of existence.
Therefore, the analysed company must aspire
after a maximum reduction of products’ defectiveness through the use of diverse methods and control
quality tools, and also by means of a detailed analysis of all potential causes that might influence the
production of faulty products.
Conclusions
Companies, which take into account both
a profit and a long lasting cooperation with a loyal
and faithful customer, have to meet the demand
of products’ quality in a much wider meaning.
Properly implemented and maintained Integrated
Management System is used as a result of a well
thought need to keep the optimal quality of products, to have a positive influence on the environment and to ensure the safety at work. It contributes
to the development of an organisation’s condition
and its image, both in the eyes of internal and
external customers.
The lack of any failures of a product, in other
words, providing a product in accordance with
a specificity and a customer’s requirements is
a desired state in all organisations, a state that gives
benefits and satisfaction not only for a producer,
but also for a recipient of a product.
A need for safety is very important from a customer’s point of view. The presented company produces components used in automotive industry.
They influence directly a user’s safety or even his
life. It is reflected in a recipient’s behaviour and
reactions in case of a lack of quality, which influ-
Zeszyty Naukowe 27(99) z. 1
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8. Internal documentation of the analyzed documentation.
Recenzent:
dr hab. inż. Zbigniew Matuszak, prof. AM
Akademia Morska w Szczecinie
97