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Poultry Processing Industry eTool

Ergonomics - Force - Hand Force
 


Most poultry processing jobs and tasks involve intensive hand activities that may expose employees to high hand forces; for example, gripping hand tools and squeezing scissors. This is especially true where employees are not provided with proper hand tools. Using improper hand tools usually requires employees to exert greater force to control and operate them. Applying high hand force repeatedly for prolonged periods can cause muscle fatigue, tendon inflammation, and contact trauma.

Factors that can increase the amount of hand force employees must exert to perform a task include:
  • Weight of hand tool — Employees must use more force to hold and operate heavy hand tools.
     
  • Size of hand tool — Employees must use more force to operate tools that do not have good weight distribution because they cannot hold the tool at the center of gravity.
     
  • Handle or grip size — Tool handles that are too small or too big reduce the employee’s grip efficiency. Improperly sized handles force employees to exert more finger force just to hold it. Continual or prolonged exertion of finger force can lead to tendon inflammation and injury, especially if the wrist is bent.
     
  • Tool activation — The way tools are activated can also increase the amount of hand force employees must exert.

    • Manual knives generally require employees to use more hand force to cut through meat than electric knives.
       
    • Tools with squeeze triggers, such as scissors and staple guns, may require employees to apply a lot of muscle contraction in the hand and fingers, especially if the object to be cut is thick or dense.
       
    • If the trigger of a tool is too small the employee may only be able to use one finger to activate it. Where all the force to squeeze the activation trigger must be generated by one finger, the tendons may be overused to the point where fluid builds up, making it difficult to bend the finger to squeeze the tool.
  • Vibration — Employees may have to use increased grip force to maintain control when operating vibrating power tools. Vibration can also desensitize the hand, requiring increased grip force to achieve the same feel of control.
     
  • Tool maintenance — Improper maintenance of tools can increase the amount of force employees must use when operating hand tools.

    • Dull knives require exertion of more force to cut through meat than properly sharpened knives.
       
    • Poorly-maintained power tools may expose employees to more vibration.
  • Cold — Working in cold temperatures or with cold air blowing across the hands reduces the blood flow to the hands and fingers, making the fingers stiff and less dexterous. When this occurs, employees must apply more force in order to maintain the same feel of control over tools and product.
     
  • Gloves — Using gloves can make grasping a hand tool or object more difficult because they may change the friction, decrease dexterity or interfere with sensory feedback. Gloves can reduce grip strength by as much as 20%.
     
  • In poultry processing, employees usually wear at least one glove on the knife hand and two on the non-knife hand.
General controls to reduce excess hand force:
  • Provide electric and power scissors and knives.
     
  • Provide tools with power grip rather than pinch grip.
     
  • Provide tools with appropriate size handle/grip–longer handles and wider grips.
     
  • Implement knife sharpening and maintenance program.


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