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CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
This chapters contains the literature review of the study relates to the scope of the study. Design aspect very important for develop ergonomic sheet metal cutters tools. Using
hand tools must be comfort to workers for the job satisfaction. Design of comfortable sheet metal cutters can be reduce the risk of occupational injury.
Basic ergonomic principles of hand tools design have been known for several decades, limited attention has been paid these principles in designed widely used industrial tools.
Guidelines has been general, lacking specify and frequently conflicting. Using hand tools relate with musculoskeletal disorder problem especially repetitive
motion injuries of the upper limb symptom. This symptom occurs when used the hand tools for the longer time period and involving repetitive work. Basic ergonomic principle
can be reducing for this problem from the design of ergonomic hand tools. Design of ergonomic related with comfortable using and prevent for repetitive motion injuries
problem.
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2.2 Repetitive Motion Injuries of the Upper Limb
The concept repetitive work refers to similar tasks performed again and again. Repetitive work of the upper extremity implies motor component, which can defined in terms of
time and force. Repetitive work of the upper extremity is considered one of several physical work load factor, associated with symptoms and injuries of the musculoskeletal
system. Other important factors are static loads, posture, and exertion of external forces. Static load occurs when muscles are kept motionless for a long time and this is
undesirable in any work situation, especially while using hand tools. The muscles become more vulnerable to fatigue and future injury.
Body posture is an effect of posture on torque exertion capability was studied in detail Mital 1986 and Mital and Channaveeriah 1988. Body posture influence using the
hand tools because prevention from the awkward posture, wrist posture and effected to the musculoskeletal injuries and repetitive motion injuries.
Exertion of external forces related with type of material or working material for the tools whether give the high strength to the musculoskeletal and give the repetitive motion
injuries of the upper limb.
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2.3 Hand Tools Ergonomics