MANUAL MATERIAL HANDLING (MMH)

Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
MANUAL MATERIAL HANDLING (MMH)
Figure 2.1 Manual Material Handling
Image source from NIOSH
A. DESCRIPTION
Definition of Manual Material Handling (MMH), according to the American Material
Handling Society is a knowledge that includes handling, displacement (moving), packaging,
storing, and controlling of material with all its forms (Wignjosoebroto & Sritomo, 1996). The
manual material handling activity should not harmful and cause pain, so it can increase the
productivity of the workers.
B. PRACTICUM OBJECTIVES
The objectives of this manual material handling practical are as follows:
a. Able to measure work in the case of manual material handling.
b. Knowing large workload during work.
c. Able to understand human limitations of the workload imposed on members of the human
body.
d. Being able to provide recommendations based on the results of the analysis.
C. INPUT AND OUTPUT
Input:
1. Operator’s data and design of appointment
2. Video appointment process
3. Screencapture of videos to be process in the determination of multiplier variables.
1
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
Output:
1. Recommended Weight Limit Analysis.
2. Lifting Index of prefix and proposal layout.
3. Repair work design recommendation.
D. BIBLIOGRAPHY
Chaffin, D. B., & Andersson, G. B. (1991). Occupational Biomechanics Second Edition.
Canada: John Wiley & Sons, Inc.
Cour, M. (n.d.). Le Campus. Retrieved Maret 29, 2015, from
http://www.lecampus.com/en/formation/manutention-manuelle-des-charges
Grandjean, E. (1986). Fiitting the Task to the Man An Ergonomic Approach. London &
Philadelphia: Taylor & Francis.
Kroemer, K., Kroemer, H., & Kroemer-ELbert, K. (1994). Ergonomics How to Design for
Ease and Efficiency. Englewood Cliffs, New Jersey: Simon & Schuster Company.
Marras, W. S., & Karwowski, W. (2006). Fundamental and Assessment Tools for
Occupational Ergonomics. London New York: Taylor & Francis.
Nurmianto, E. (2004). Ergonomi Konsep Dasar dan Aplikasinya. Surabaya: Guna Widya.
Safety, C. C. (2013, Maret 28). CCOHS. (Canadian Center for Occupational Health and
Safety) Retrieved Maret 29, 2015, from
http://www.ccohs.ca/oshanswers/ergonomics/mmh/hlth_haz.html
Tayyari, F., & Smith, J. (1997). Occupational Ergonomics : Principles and Applications.
Chapman & Hall.
Waters, T. (1994). Applications Manual for the Revised NIOSH Lifting Equation. DHSS
(NIOSH) Publication NO. 94-110,32.
Wignjosoebroto, & Sritomo. (1996). Tata Letak Pabrik dan Pemindahan. Surabaya: Institut
Teknologi Sepuluh November.
2
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
E. TEORITICAL BASED
E.1. Manual Material Handling
Manual handling is an activity that included in the category of heavy work. Lifting and
lowering is one example of in manual material handling tasks. Risk factors that may occur
when the appointment is wrong will affect too heavy burden on the muscles, tearing of the
intervertebral discs and interference on the backs of workers (Grandjean, 1986).
According Nurmianto (2004), the removal of material manually if not done
ergonomically will lead to accidents in the industry. Industrial accidents are referred to as
"overexertion of lifting and carrying" IE tissue damage caused by the excessive lifting load.
Besides the issue of the appointment, one of the factors that also must be considered is the load
that lifted. Since the removal of manual handling widely applied in the workplace, such as
lifting and pushing tasks has become a common thing in the industry nowadays. Examples of
work manually appointment is like pulling or pushing a trolley, transport box, using tools,
hygiene and move using tools like hydraulic lifts. As a result of the manual removal itself, the
potential for increased risk of injury to the spine may occur depending on the height, position
and weight of the object. (Resnick and Chaffin, 1996).
The heavier the load that lifted, the greater the risk of injury faced by workers, so there
must be a limit load raised by the workers. Therefore, NIOSH devises a formula that can be
used to determine the limits of the lifted load at a removal activity called the Recommended
Weight Limit (Kroemer, Kroemer, & Kroemer-Elbert, 1994).
E.2. Lifting Restrictions of Manual Material Handling
Human performance in making the appointments have many limitations. Experts of the ILO
(International Labor Organization) in Chaffin and Andersson (1991) found the manual
handling would affect the impact on:
1. The potential for injury to the back of the spine, knees, shoulders and hips.
2. Potential wound infection in the elbow the hands and feet.
According to Chaffin (1991), some types of work can be considered and are divided into several
groups simultaneously by a factor of the type which is intended to minimize disruption
3
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
musculoskeletal separately related to the use and removal of material. These factors can be
grouped into:
1. Characteristics of workers
2. Materials and characteristics of the tools and materials
3. Work practice
E.3. RWL (Recommended Weight Limit)
NIOSH (National Institute of Occupational Safety and Health) as an agency that deals with the
health and safety of workers in America conducted a research related to human strength in
lifting or moving a load. The recommendation aims to suppose that humans can raise the load
limit without causing injury, even though the job is done repeatedly in a considerable period.
In 1991, NIOSH recommends equation formulation of loading or lifting equation. The result
refreshes to the Recommended Weight Limit (RWL) formula, which is the loading conditions
without incurring the risk of injury, especially back pain injury.
Recommended Weight Limit is a recommendation that humans can raise the load limit
without causing injury, even though the work is done in a repetitive and long periods. The
RWL is set by NIOSH in 1991 in the United States. NIOSH equation applies in the
circumstances:
1. The load that given is a static load, no increase or reduction in load the middle of the
job.
2. The load lifted with both hands.
3. Appointment or decrease objects made within a maximum of 8 hours.
4. Appointment or decrease objects should not be done while sitting or kneeling.
5. The workplace is not cramped.
6. The appointment should not be too fast and not the position of the feet propped up on
a narrow and slippery surfaces.
4
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
Figure 2.2 Position Apporintment of Recommended Weight Limit
The equation to determine the recommended load to be lifted a worker under certain
conditions according to NIOSH are as follows:
RWL = LC x HM x VM x DM x AM x FM x CM
Description:
LC = Load constant
= 23 kg
HM = Horizontal Multiplier
= 25 / H
FM = Frequency Multiplier *see tabel 2.1
CM = Coupling Multiplier (handle) *see tabel 2.2
5
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
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: 6th
:2
: 21-23 April 2015
VM = Vertical Multiplier
VM = 1 – 0,00326 |𝑉 − 75|
DM = Distance Multiplier
DM = 0,82 +
4,5
𝐷
AM = Asimetric Multiplier
AM = 1 – 0,0032 . A
Note (see figure 2.2 for description of each multiplier)
To get the value of the multiplier obtained from each of the variables, with the following
details:
H = The distance of the load that lifted towards the center point of the body (cm)
V = The distance of the load that lifted towards the floor (cm)
D = Difference in load displacement distance vertically (cm)
A = Angle of rotation symmetry formed body (0)
For Frequency Multiplier is determined by using the FM table below in table 2.1. By
knowing the frequency of force per minute and also the value of V in inches.
Table 2.1 Table of Frequency Multiplier
Working duration
Lifting frequency/mnt

1 hours  t  2 hours
1 hours
2 hours  t  8 hours
V < 30
V  30
V < 30
V  30
V < 30
V  30
 0.2
1.00
1.00
0.95
0.95
0.85
0.85
0.5
0.97
0.97
0.92
0.92
0.81
0.81
1
0.94
0.94
0.88
0.88
0.75
0.75
2
0.91
0.91
0.84
0.84
0.65
0.65
3
0.88
0.88
0.79
0.79
0.55
0.55
4
0.84
0.84
0.72
0.72
0.45
0.45
5
0.80
0.80
0.60
0.60
0.35
0.35
6
0.75
0.75
0.50
0.50
0.27
0.27
7
0.70
0.70
0.42
0.42
0.22
0.22
8
0.60
0.60
0.35
0.35
0.18
0.18
9
0.52
0.52
0.30
0.30
0.00
0.15
10
0.45
0.45
0.26
0.26
0.00
0.13
(F)
6
Faculty
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: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
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:2
: 21-23 April 2015
Working duration
Lifting frequency/mnt

1 hours  t  2 hours
1 hours
2 hours  t  8 hours
11
0.41
0.41
0.00
0.23
0.00
0.00
12
0.37
0.37
0.00
0.21
0.00
0.00
13
0.00
0.34
0.00
0.00
0.00
0.00
14
0.00
0.31
0.00
0.00
0.00
0.00
15
0.00
0.28
0.00
0.00
0.00
0.00
>15
0.00
0.00
0.00
0.00
0.00
0.00
Description: for the removal frequency less or only one time in 5 minute set F = 0.2 lifts /
min.
For coupling Multiplier Factor (handle) can be specified in Table 2.2 below:
Table 2. 2 Coupling Multiplier
Coupling Multiplier
Coupling
V < 30 inches
V > 30 inches
Type
(75 cm)
(75 cm)
Good
1.00
1.00
Fair
0.95
1.00
Poor
0.90
0.95
An explanation of the classification of the clutch can be seen in Table 2.3 below (Tayyari &
Smith, 1997)
Table 2.3 Coupling classification
Good
Fair
Poor
Good coupling has a good grip
Fair coupling is defined as
A container that has a less
between the hand and the
a handle with a design that
than optimal design or
object is defined as a good
lacks the optimal design
loose parts or large objects
container coupling
(see note 4).
uneven, difficult to handle
classification or have the
or pick the sharp edges
optimal design. (See notes 1-3).
(see note 5).
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Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
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: 6th
:2
: 21-23 April 2015
For the seperated components /
For a container that has an
Lifting the surface is not
loose or uneven objects, which
optimal design, but do not
hard (eg rice sacks)
are usually not placed in a
have a handle or to an
container, such as printed
object that is not flat, fair
material and storage, good
coupling is defined as a
coupling is defined as a
handle, which can be bent
comfortable pair, which are
hands around 90º (see note
easily able to hold hands
4).
around the object (see note 6 ).
Note:
1. A draft optimal grip has a diameter of 1.9 to 3.8 cm, length ≥ 11.5 cm, tolerance ≥ 5
cm, cylindrical shape, and the surfaces are smooth and do not slip.
2. A hand grip or less have the following characteristics; 3.8 cm high, 11.5 cm long, semioval shape, tolerance ≥ 5 cm, smooth surface and does not slip, and ≥ 0.6 cm thick
container. (Eg thick cardboard).
3. A container has an optimal design, when the front length ≥ 40 cm, height ≥ 30 cm, and
the surface is smooth and does not slip.
4. Workers should be able to bend his fingers around 90º below the container. As required
when lifting a box from the floor.
5. A container is considered less than optimal if it has both front length ≥ 40 cm, height ≥
40 cm, rough surface and skid, sharp tip, the asymmetric center of mass, the contents
of which are unstable, or require the use of gloves.
6. Workers must be able to cover the object with his hands around without causing
excessive wrist deviation or unusual posture and grip does not require excessive force.
For more details, coupling classification can be seen in Figure 2.3 below (Tayyari and
Smith, 1997):
8
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
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:2
: 21-23 April 2015
Object Lifted
Container
(Keranjang)
Container
(Keranjang)
Optimal?
Loose Object
(Benda Bebas)
NO
YES
Bulky Object?
(Benda Besar)?
NO
YES
POOR
Tungkai (Handle)
Optimal?
Genggaman (Grid)
Optimal?
NO
NO
Jari - Jari
memebentuk
sudut 90 derajat
NO
YES
FAIR
YES
YES
Good
Figure 2.3 Flowchart Decision Tree coupling classification
After RWL score is known, then do the calculations of Lifting Index. To know the rapture
index which does not contain the risk of spinal injury can be sought by this following
equation:
LI 
Load Weight
L

Recommende d Weight Limit
RWL
9
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
Description:
If LI  1, then the activity does not contain the risk of spinal cord injury. Otherwise, if LI
> 1, then the activity is the risk of spinal cord injury.
10
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
RWL Study Case
A worker took the box with a weight of 5 kg over the conveyor 15 cm and raised to a table with
a height of 125 cm from the floor. Distance to the center point of the body load is 35 cm. Angle
of rotation symmetry of the body formed 45o. If during the 80 minutes of the workers making
the appointments as much as 224 times, with a duration of 2 hours. How much the
recommended load limit will gain? Whether the work is considered safe or not? (note Handle
Coupling in the category Fair)
Completion:
L= 5 kg
LC = 23 kg
V = 15 cm
Handle Fair = 0, 95
D = 110 cm
H = 35 cm
A = 45o
Calculation,
25
25
HM
=
VM
= 1- 0, 00326 |𝑣 − 75| = 1- 0, 00326 |15 − 75| = 0, 8044
DM
= 0, 82 +
FM
=
AM
= 1-0,0032A = 1-(0,0032x45) = 0,856
CM
= 0, 95 (see CM table)
LC
= 23
𝐻
=35= 0,714
224 𝑙𝑖𝑓𝑡
80 𝑚𝑛𝑡
4,5
4,5
𝐷
110
= 0.82 +
= 0.861
= 2.8 = 3 (see FM table) the score is 0, 79
So,
RWL = LC
*
HM
*
VM
*
DM
*
AM
*
FM
*
CM
RWL = (23) (0.714) (0, 8044) (0.861) (0.856) (0.79) (0.95)
= 7,306
Then calculate the Lifting Index (LI) with following equation,
LoadWeight
L
5


Re commended _ Weight _ Limit RWL 7,306
LI  0,68
LI 
11
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
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Date
: 6th
:2
: 21-23 April 2015
Conclusion:
Recommended work load is equal to 7.306, while the removal is done only by 5 kg, then the
given workload can be increased (preferably no more than 7.306 kg) in order to work more
productively.
Becasuse LI ≤ 1, then the activity does not contain the risk of spinal cord injuries to workers
and working methods should be retained and the data can be used for comparison in the
recruitment of new workers.
Implementation of practical study
1. Task
Make an observations of Manual Materials Handling (according to the provisions that
have been announced in the laboratory) and try to analysis using Recommended Weight
Limit (RWL) approach. Calculate Lifting Index observations removal activities. If the LI
is the risk of injury, make recommendations and count back LI based layout proposals.
2. Equipment and Materials
1. Ruler or gauges
2. Bows
3. Camera
4. Scales weight
5. Worksheets
3. Practical Implementation Procedures
1. Measure the mass of the object is lifted.
2. Position your operator in the field of appointment.
3. Record the operator’s variable.
4. Operator workload lift origin-destination for 2 minutes.
5. After recording, the practitioner make a screen capture of the video removal done.\
6. Perform processing and analysis RWL.
7.
Perform processing and analysis Lifting Index.
8. Interpretation LI categories including whether secured or not, explain the causes of
unsafe Lifting index of the variable of the operator.
12
Faculty
Major
Practicum
: Industrial Technology
: Industrial Engineering
: Work System Design & Ergonomics
Meeting
Modul
Date
: 6th
:2
: 21-23 April 2015
9. Provide recommendations or proposals repair.
10. Calculate Lifting Index of the recommendation.
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