Ergonomic design of hammer handle to reduce musculoskeletal disorders of carpenters

Abstract

The musculoskeletal disorders (MSDs) are the most common work-related health problems in Bangladesh, affecting thousands of carpenters. Typically, musculoskeletal disorders affect the elbow, neck, shoulders and wrist pain during wooden work. The aim of this paper is to focus on certain important aspects of hammer use in occupational work situations, with an emphasis on comfort or discomfort in using hammer according to users. The study concluded that it was necessary to redesign the hammer to reduce the musculoskeletal disorders. Anthropometric data of 300 male carpenters (age: 45.23±11.65 years) in SouthWestern districts of Bangladesh were measured. The ergonomically designed multipurpose hammer reduces the musculoskeletal disorders mainly wrist pain 87% to 72%.

Full text

International Journal of Research in Advanced Engineering and Technology
78
International Journal of Research in Advanced Engineering and Technology
ISSN: 2455-0876
Impact Factor: RJIF 5.44
www.newengineeringjournal.in
Volume 4; Issue 2; May 2018; Page No. 78-83
Ergonomic design of hammer handle to reduce musculoskeletal disorders of carpenters
MT Haque1
1 Department of Industrial and Production Engineering, Jessore University of Science and Technology, Bangladesh
Abstract
The musculoskeletal disorders (MSDs) are the most common work-related health problems in Bangladesh, affecting thousands of
carpenters. Typically, musculoskeletal disorders affect the elbow, neck, shoulders and wrist pain during wooden work. The aim of
this paper is to focus on certain important aspects of hammer use in occupational work situations, with an emphasis on comfort or
discomfort in using hammer according to users. The study concluded that it was necessary to redesign the hammer to reduce the
musculoskeletal disorders. Anthropometric data of 300 male carpenters (age: 45.23±11.65 years) in South-Western districts of
Bangladesh were measured. The ergonomically designed multipurpose hammer reduces the musculoskeletal disorders mainly wrist
pain 87% to 72%.
Keywords: hand tools, anthropomentry, musculoskeletal disorders, handle and power grip
1. Introduction
A hammer is a simple force amplifier that works by
converting mechanical work into kinetic energy and back [1].
Existing non-powered traditional hammer contains a head and
a handle, which can be fixed together by a special wedge or by
glue, or both. This construction is often used to combine a
compressed metallic striking head with a non-metallic shock
absorbing handle to reduce user fatigue from repeated strikes
[2-4]. Hammer is one kind of the best hand tool which todays
used for various function of household, machinery and
industrial works [5]. Hammer is one of the most important
hand tool used in carpentry. But an improper designed
hammer may cause significant musculoskeletal disorders
(MSDs) [6]. Musculoskeletal disorders (MSDs) are currently
most critical problems faced by the ergonomists in the
workplace [7]. Workplace injuries are extremely severe in
these types of industries. Poor working conditions and the
absence of workers have resulted in a very high incidence of
MSDs [8]. Ergonomically designed hand tools reduce the risk
of occupational disorders of the upper limbs. They also
provide comfortable work for the workers and give high
production rate [9]. Ergonomics is the scientific discipline
concerned with the understanding of interactions among
humans and other elements of a system, and the profession
that applies theory, Principles, data and methods to design in
order to optimize human well-being and overall system
performance [10]. Several researchers designed some non-
powered tools such as shovel, hammer, screw driver etc. In
that case they were focused on the comfort and discomfort
issues based on some parameter [11-17]. Grip size and diameter
is important parameter to design a hand tool. Proper gripping
improves the efficiency of the wooden work [18]. This study
was focused on hammer handle related injuries in traditional
carpentry or wooden work and controlling the rate of injury
through ergonomic study and designing new multi-purpose
hammer. In this study authors are trying to prevent the
ergonomic discomforts and injuries mainly wrist pain which
occurs most of the time using traditional hammer.
2. Methodology
A. Material and Methods
The study was conducted during 20th August 2017 to 20th
October 2017 in different areas of Bangladesh. In this study,
there were 300 carpenter’s respondents. All of them were
willing to participate in this study. A survey was conducted on
the types of hammers were used in Carpentry work. Following
figures-1 & 2 shows the design of hammers available in south-
western areas of Bangladesh [18-20].
Fig 1: (a) Carpenters hammer, (b) Bumping hammer, (c) Ball- peen
hammer
Carpenters hammer is a hammer with a cleft at one end for
pulling nails. Its broadly uses in carpenter industry. Bumping
hammer is a power-driven hammer with two broad flat faces
on a narrow head. It is used in bumping sheet metal. It is a
hammer have a rounded, hence “ball”, peen which used for
shaping metal closing rivets and rounding edges off metal pins
and fasteners. It is also used for hitting chisels and punches
during carpenter work.

International Journal of Research in Advanced Engineering and Technology
79
Fig 2: (d) Claw hammer, (e) Locksmiths hammer, (f) Masons
hammer
Claw hammer is a hammer with a heavy rigid head and a
handle. It is basically used to deliver an impulsive force by
striking. Locksmiths hammer is a German pattern hammer
with colored end of handle and basically handle made of
wood. Basically used to create high pressure & force.
Mansions hammer is a hammer with a moderately heavy head
sharpened at one end to a chisel edge. This types of hammer
specially used for removing pin from wood.
B. Measurement of existing hammers
The hammers are widely used in the carpentry and wooden
work in Bangladesh. Many existing hammers are not
ergonomically designed because they require a lot of wrist
bending and twisting during use. In this survey work
researchers took the measurement (Handle diameter, Grip
Size) of the different existing hammers shows in figure-3.
Fig 3: Measurements of hammers
C. Anthropometric measurements of hand
Hand length (HL): The length of the hand as measured
between the wrist crease and the tip of the longest finger on
the hand, usually thumb finger.
Hand breadth (HB): The length of the palm of the hand,
measured perpendicular to hand length.
Finger length (FL): The length of the thumb finger as
measured between the palmar digital and the tip of the middle
finger.
Hand breadth at metacarpal (HBM): The maximum breadth
across the hand where the fingers join the palm. The right
hand is extended straight and stiff with the fingers held
together.
Fig 4: Hand anthropometry
D. Determination of an optimal cylindrical handle
diameter for power grip
In this study researchers use following equations to determine
the general grip, power grip diameter and grip size [21-29]:
…….... [1]
= ..... [2]
…….……….. [3]
E. Skewness test
According to Fan and Gencay (1995) [30], Hamilton (1989) [30-
31] following equations is used to calculate the skewness:
……………….... [4]
If the skewness is between the -0.5 and 0.5, the data are
approximately symmetric.
 If the skewness is between -1 and -0.5 or between 0.5 and
1, the data are moderately skewed.
 If the skewness is less than -1 or greater than 1, the data
are highly skewed.
3. Results
A. Ergonomic selection of musculoskeletal disorders
The Figure-5 and Table-1 presents the prevalence of
musculoskeletal disorders in different body regions of
carpenters. As Figure-5 shows, the most commonly affected
parts are wrist, shoulder and elbow.
Table 1: Frequencies of ergonomic discomforts and injuries
Musculoskeletal
Disorders
No. of
Workers
Percentage of
Workers (%)
Headache
150
50
Shoulder pain
195
65
Wrist pain
260
87
Stiffness in finger
215
72
Soreness in elbow
183
61

International Journal of Research in Advanced Engineering and Technology
80
In this study the prevalence of musculoskeletal disorders
among carpenters were 87% for the wrist pain due to improper
ergonomically designed hammer. Other musculoskeletal
disorders among workers were 72% for the stiffness in finger
and 75% for shoulder pain [32, 33].
Fig 5: Frequencies vs. Musculoskeletal Disorders (After using existing hammer)
Survey results shows that 69% carpenters want to improve in
working conditions, other result shows that more than 55% of
carpenters do not satisfied with their working environments.
47% workers want to redesign the hammer because of they are
not comfortable with exiting hammer. Most of carpenters
suffer from various musculoskeletal disorders which are not
good for long time, so that they want to improve the design of
their hammer [34-38].
B. Overall dimensions of hammers available in different
areas of Bangladesh
The overall dimensions of existing hammers were recorded
from different areas of Bangladesh show in following table.
Table 2: Dimensions of existing hammers
Parameter
Handle length(cm)
Handle diameter(cm)
Average
32.35
2.95
SD
0.516
0.06
Max
33
3.1
Min
31
2.89
5th Percentile
31.6
2.896
50th Percentile
32.5
2.95
95th Percentile
33
3.04
C. Anthropometric measurements of the Carpenter
Table 3: Anthropometric measurements
Man
Age
MFL
TL
IGB
HBM
HB
HL
MFL
Average
45.2
7.87
3.01
4.16
7.63
8.48
18.69
7.87
SD
11.7
0.487
0.34
0.47
0.49
0.45
1.18
0.487
Max
75
9.7
3.9
5.1
8.9
9.6
23.4
9.7
Min
23
6
2.3
3.4
6.4
7
16.4
6
5th %le
26
7.2
2.5
3.5
6.9
7.8
17.1
7.2
50th %le
45
7.9
3
4.1
7.6
8.5
18.5
7.9
95th %le
65
8.695
3.69
4.8
8.495
9.2
21
8.695
D. Skewness test of existing hammer
Table 4: Skewness test
Statistic
Handle length (cm)
Handle diameter (cm)
Mean
32.35
2.95
SD
0.516
0.06
Median
32.28
2.98
Skewness
0.41
-1.5
Evaluation
Approximately symmetric
Highly Skewed
E. Proposed dimensions and design of ergonomically
designed hammer
Table 5: Proposed dimensions
Features
Dimensions (cm)
Used Equations
Optimal grip diameter
3.368
[1]
Power grip diameter
3.739
[2]
Grip size
11.747
[3]
Fig 6: CAD Design (Isometric View)

International Journal of Research in Advanced Engineering and Technology
81
Fig 7: CAD Design (2D Drawing)
Fig 8: CAD design of newly designed hammer
F. Flexibility Analysis
Table 6: Ergonomically designed hammer vs. Existing hammer
Comfort factors
Ergonomically
designed hammer
Existing
Hammer
Quality of the hammer handle
Good
Good
Surface Finish of hammer handle
Good
Good
Compatibility for the type of grip
Excellent
Normal
Overall Comfort at first look
Excellent
Normal
Fits the hand
Excellent
Bad
Effect of hammer use on hand/arm
Good
Worst
G. Experimentation for ergonomically designed hammer
handle
Table 7: Experimentation for optimal diameter
Evaluation
Description
Grip size is too
small
The two middle fingers are digging into the
heel portion of the operator palm.
Grip size is
correct
The two middle fingers are slightly gapped to
touching the heel portion of the operator palm.
Grip size is too
large
The two middle fingers have too much gap to
the heel portion of the operator palm.
The authors have found that the Grip size is correct and the
compatibility of grip is excellent. It fits with hand
comfortably.
I. Validation and Testing
The Figure-9 presents the prevalence of musculoskeletal
disorders in different body regions of workers after using new
designed multi-purpose hammer.
Fig 9: Frequencies vs. Musculoskeletal Disorders (After using new designed hammer)
4. Discussion
In this study, the authors survey different areas in Bangladesh.
Here the authors have found that the carpenters were facing
high level of wrist pain after carpentry or wooden work. For
this reason, the authors were recorded some significant
anthropometric measurements for purpose of designing
ergonomically correct hammer handle to prevent the wrist
pain.
5. Conclusion
The purpose of this study has been fulfilled; a hammer handle
for power grip operation has been developed and
implemented. However the workers found that their working
postures with new multipurpose hammer is good and reported
comfort. Results shows that wrist pain was the big of
musculoskeletal disorder of carpenters which have been
reduced to 72% from 87%.
6. Future Scope
In this study, anthropometric data were collected from 300
male carpenters of South-Western districts in Bangladesh. As
the scenario of wooden working condition in most of the
districts in Bangladesh is almost the same, the provided injury
and discomfort related data can be a great resource for the
administration and for social workers to understand the
working condition in carpentry industries of Bangladesh. In

International Journal of Research in Advanced Engineering and Technology
82
this study, research could not perform dynamic simulation of
hammer operation for lack of facility. It will be makes the
proposed hammer model more validate.
7. Acknowledgments
The authors are pleased to acknowledge Monir Ahmed,
Mahian Haque, Shamir Kumar, Shahinur Rahman and Nipen
Kar for their cooperation and assistance in conducting surveys
and collecting data in this study. The authors are also thankful
to Dr. Deepak Kumar Biswas (Assistant Surgeon, United
Health Complex, Jessore), Dr. Motiur Rahman (Assistant
Surgeon, Pirojpur Sadar Hospital, Pirojpur), and Dr. Siddharth
Kar (Assistant Registrar, Medicine, Jessore Medical College,
Jessore) for their help, support, and consultation through the
study.
8. Conflicts of Interest
The authors declare that they have no conflicts of interest.
9. Ethical Statement
The authors declare that they have followed ethical
responsibilities.
10. References
1. Dul J, Neumann WP. Ergonomics contributions to
company strategies Applied Ergonomics. 2009;
40(4):745-752.
2. Motamedzade M, Choobineh A, Mououdi MA, Arghami
S. Ergonomic design of carpet weaving hand tools,
International Journal of Industrial Ergonomics. 2007;
37(7):581-587.
3. Choobineh A, Hosseini M, Lahmi M, Khani R,
Shahnavaz H. Musculoskeletal problems in Iranian hand-
woven carpet industry: guidelines for workstation design,
Applied Ergonomics. 2007; 38(5):617-624.
4. Fraser TM. Ergonomics principles in the design of hand
tools, Occupational Safety and Health series, Geneva.
1980, 44.
5. Pheasant S, Neil OO. Performance in gripping and
turning: A study in hand/handle effectiveness, Applied
Ergonomics. 1975; 6(4):205-209.
6. Greenburg L, Chaffin DB. Workers and their tools: a
guide to the ergonomic design of hand tools and small
presses, Pendal Publication Company, Midland, 1977,
249-253.
7. Tichauer ER, Gage H. Ergonomic principles basic to hand
tool design, Am Ind Hyg Assoc Journal. 1977; 38:622-
634.
8. Hustan T, Sanghavi N, Mital A. Human torque exertion
capabilities on a fastener device with wrenches and
screwdrivers, in Trends in ergonomics/human factors I
North Holland, Amsterdam, 1984, 51-58.
9. Mital A. Effect on body posture and common hand tools
on peak torque exertion capabilities, Applied Ergonomics.
1986; 17:87-96.
10. Johnson SL, Childress LJ. Powered screwdriver design
and use tool, task and operator effects, International
Journal of Industrial Ergonomics. 1988; 2:183-191.
11. Mital A, Channaveeraiah C. Peak volitional torques for
wrenches and screwdrivers, International Journal of
Industrial Ergonomicsme. 1988; 3:41-64.
12. Radwin RG, VanBergeijk R, Armstrong TJ. Muscle
response to pneumatic hand tool torque reaction forces,
Ergonomics. 1989; 32(6):665-673.
13. Ulin SS, Ways CM, Armstrong TJ, Snook SH. Perceived
exertion and discomfort versus work height with a pistol-
shaped screwdriver, Am Ind Hyg Assoc Journal. 1990;
51:588-594.
14. Aghazadeh F, Mital A. Injuries due to hand tools; results
of a questionnaire, Applied Ergonomics. 1987; 18(4):273-
278.
15. Christensen AD, Bishu R. Hand tool design: are
biomechanical criteria the same as aesthetic criteria? A
preliminary study In: Proceedings of the IEA 2000/HFES,
Congress. 2000; 4-564-4-577.
16. Aptel M, Claudon L. Integeration of ergonomics into
hand tool design: principle and presentation of an
example, International Journal of Occupational Safety
and Ergonomics. 2002; 8(1):107-115.
17. Marsot J, Claudon L. Design and ergonomics Methods for
integrating ergonomics at hand tool design stage”,
International Journal of Occupational Safety and
Ergonomics. 2004; 10(1-2:7-21.
18. Vink P, Overbeeke CJ, Desmet PMA. Comfort and
design, principles and good practice, Comfort experience.
In: Vink. P. (Ed.), CRC Press, Boca Raton, 2005.
19. Kuijit-Evers LFM, Twisk JWR, Groenestejin L, de Looze
MP, Vink P. Association between objective and
subjective measurements of comfort and discomfort in
hand tools, Applied Ergonomics. 2007; 38:43-654.
20. Fellows GL, Freivalds A. Ergonomics evaluation of a
foam rubber grip for tool handles Applied Ergonomics.
1991; 22(4):225-230.
21. Chao A, Kumar AJ, Emery CTND, Nagarajarao K, You
H. An ergonomic evaluation of cleco pliers, Proceedings
of the IEA 2000/HFES Congress. 2000; 4-441-444-2.
22. Kuijit-Evers LFM, Groenesteijn L, Looze MP, Vink P.
Identifying factors of comfort in using hand tools,
Applied Ergonomics. 2004; 35:453-458.
23. Mano H, Oliver RL. Assessing the dimensionality and
structure of the consumption experience: evaluation,
feeling, and satisfaction, Journal of Consum. Res. RL.
1993, 451-466.
24. Helander MG, Zhang L. Field studies of comfort and
discomfort in sitting, Ergonomics. 1997; 40(9):895-915.
25. Liu WCV, Sanchez-Monroy D, Parga G. Anthropometry
of female maquiladora workers International Journal of
Industrial Ergonomics. 1999; 24:273-280.
26. Lin YC, Wang MJ Wang EM. The comparisons of
anthropometric characteristics among four peoples in East
Asia, Applied Ergonomics. 2004; 35:173-178.
27. Resnick M. Estimating the anthropometry of international
populations using the scaling ratio method, Proceedings
of the Human Factors and Ergonomics Society, 39th
Annual Meeting, 1995, 673-677.
28. Chandna P, Deswal S, Chandra A. An anthropometric
survey of industrial workers of the northern region of
India, International Journal of Industrial and Systems
Engineering. 2010; 6(1):110-128.
29. Chakrabarti D. Indian Anthropometric Dimensions for

International Journal of Research in Advanced Engineering and Technology
83
Ergonomic Design Practice, National Institute of Design.
Ahmedabad, India, 1997, 27.
30. Fan Y, Gencay R. A Consistent Nonparametric Test of
Symmetry in Linear Regression Models, Journal of the
American Statistical Association. 1995; 90:551–557.
31. Hamilton J. A New Approach to the Economic Analysis
of Non-Stationary Time Series and the Business Cycle,”
Econometrica. 1989; 57:357-384.
32. Jarque, C, Bera A. Efficient Tests for Normality,
Homoskedasticity and Serial Independence of Regression
Residuals, Economics Letters. 1980; 12:255-259.
33. Chandra A, Chandna P, Deswal S. Hand Anthropometric
Survey of Male Industrial Workers of Haryana State
(India), Industrial and Systems Engineering. 2011;
9(2):163-182.
34. Meena ML, Dangayach GS, Bhardwaj A. Measuring
Quality of Work Life Among Workers in Handicraft
Industries of Jaipur, International Journal of Industrial
and Systems Engineering. 2014; 17(3):376-390.
35. Meena ML, Dangayach GS, Bhardwaj A. Investigating
Ergonomic Issues among workers in Hand Block Textile
Printing Industries, International Journal Business and
Systems Research. 2014; 8(4):392-401.
36. Dewangan KN, Owary C, Datta RK. Anthropometry of
male agricultural workers of north-eastern India and its
use in design of agricultural tools and equipment,
International Journal of Industrial Ergonomics. 2010;
40(5):560-573.
37. Kumar GS, Das A. Analysis and ergonomic improvement
of working postures in cast house work station using
JACK modelling, International Journal of Human Factors
Modelling and Simulation. 2012; 3(1):16-31.
38. You M, Lyu G, Chen I. An ergonomic approach to oyster
knife design and evaluation a preliminary result, National
Yunlin University of Science and Technology,
Department of Industrial Design Yunlin, Taiwan. 2009,
2427-2435.