ErgonomicsErgonomics

DR. SITI ZAWIAH MD. DAWALDR. SITI ZAWIAH MD. DAWALDEPT. OF ENGINEERING DESIGN DEPT. OF ENGINEERING DESIGN

AND MANUFACTUREAND MANUFACTUREUNIVERSITY OF MALAYAUNIVERSITY OF MALAYA

IntroductionIntroduction

Human hand is able to Human hand is able to perform a large variety of perform a large variety of activities ranging from those activities ranging from those that require fine control to that require fine control to others that demand large others that demand large forces.forces.

Hand tasksHand tasks can be divided: can be divided:

Fine manipulation of objects with little Fine manipulation of objects with little displacement and forces.displacement and forces.

Fast movements toward the object, Fast movements toward the object, requiring moderately accuracy to reach requiring moderately accuracy to reach the target but a fairly small exertion of the target but a fairly small exertion of force. force.

Forceful activities with little or moderate Forceful activities with little or moderate displacementdisplacement

Forceful activities with large Forceful activities with large displacementsdisplacements

Designing Hand Designing Hand ToolsTools

Fit the ToolFit the Tool

Hand tools need to fit the Hand tools need to fit the contours of handcontours of hand

Hand tools need to held securely Hand tools need to held securely with straight wrist and suitable with straight wrist and suitable arm posturesarm postures

Hand tools must utilize strength Hand tools must utilize strength and energy capabilities without and energy capabilities without overloading the body. overloading the body.

Many methods of grippingMany methods of gripping

Power GripPower Grip

Force parallel to forearmForce parallel to forearm Force at an angle of forearmForce at an angle of forearm Force acting on a moment armForce acting on a moment arm Grip is used for force or holding heavy Grip is used for force or holding heavy

product product

Pinch Grip Pinch Grip

Tools is held between the distal ends of Tools is held between the distal ends of one or more fingers one or more fingers

4 types:4 types:- Lateral pinchLateral pinch- Pulp pinchesPulp pinches- Palm pinchPalm pinch- Finger pressFinger press

Avoid Tissue CompressionAvoid Tissue Compression

Handle DesignHandle Design

Oblique thrust lineOblique thrust line

FormfittingFormfitting

Grip Strength CapabilityGrip Strength Capability

Pulp Pinch Strength Pulp Pinch Strength CapabilityCapability

Proper orientation of Proper orientation of power tools in workplacepower tools in workplace