Manufacturing Ergonomics Newsletter

Manufacturing Ergonomics Newsletter
Look for different Ergonomic articles every other month
Articles in February 2005
- Handtool Checklist - Ergonomics & Behavior - What is Epicondylitis?

Handtool Checklist
If the answer is "yes" to any of the following questions
Does the use of handtool require ?	Cycle time
1) bending of the wrist	< 10 sec.
2) raising elbows on the side	< 30 sec.
3) forward extended reach	< 30 sec.
4) lifting handtools 1 lb. or heavier	< 30 sec.
5) excessive grip force.	< 30 sec.
6) pressure at palm of the hand	< 30 sec.
7) rotation of the wrist	< 10 sec.
8) trigger action using one finger	< 10 sec
9) pinch grip action	< 30 sec.
10) vibration in the hand	< 30 sec.
11) force with bulky gloves	< 30 sec.
12) large grip span	< 30 sec.
13) opening/closing handtool jaws	< 10 sec.
14) holding hot or cold tool handles	< 30 sec.
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Ergonomics & Behavior
Employee attitude and behavior is affected by :
1) Human nervous system: the employee's efficiency & productivity is constantly governed by the nervous system of the employee. It takes place in three steps Step 1: The employees receive information through their sensory organs, (for example eyes, ears, nose and skin) which is then transmitted to their brain. Step 2: The brain processes this information based on individual employee's previous knowledge and experiences Step 3: The information is then transmitted to the muscles which helps the employee to continue doing the physical work or stop the work
2) Pain-pleasure principle: Human beings always move away from pain and move towards pleasure. Muscle fatigue and musculoskeletal stresses in the body are interpreted as pain by the nervous system.
Poor ergonomic design of manufacturing processes can increase muscle fatigue and musculoskeletal stresses. The nervous system causes the employee to stop the work and neutralize muscle fatigue and musculoskeletal stresses ; in other words "waste time".
This is in direct conflict with the supervisor's objective to meet production goals. The result is constant negative interactions between the supervisor and their employees, leading to deterioration of employee behavior & morale.
Conclusion: Increases and decreases of muscle fatigue and musculoskeletal stresses are the key to employee productivity, attitude, morale and most of all BEHAVIOR.
Recommendations: Reduce muscle fatigue & musculo-skeletal stresses by using ergonomic solutions on :
a) Workstation design b) Handtool application c) Method of operation d) Awkward postures
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What is Epicondylitis?
Tendons connect arm muscles to bones at the elbow joint. Twisting of the wrist causes fatigue of these muscles & stress on the tendons. Over time, the tendons develop inflammation causing elbow pain. The elbow joint is known as Epicondyle and therefore this CTD is called Epicondylitis.
Root causes of Epicondylitis
1) Repetitive bending and twisting of the wrist every 10 seconds or less
2) Rotation of the forearm during handling of heavy parts with one hand
Recommended solutions
1) Improve workstation design to prevent bending wrist
2) If the job requires repetitive twisting of the wrist (every 10 seconds or less) then use power tools.
3) Avoid rotation of the forearm by changing the method of gripping and handling heavy parts.
4) If above solutions are not possible then do stretching exercise for arm muscles every half hour for 15 seconds.
Forearm stretch flexion: Firmly hold the wrist flexed with arm fully extended. Hold it for 4-5 seconds, repeat it 4 times.		Forearm stretch extension: Firmly hold the wrist back with arm fully extended. Hold it for 4-5 seconds, repeat it 4 times.
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