Transcript Workstation Design Ergonomic design considerations Product/equipment Job aids

Workstation Design
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Ergonomic design considerations
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Product/equipment
Job aids
User selection
Training the user
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Example 1
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Example 2
BEFORE
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Example 3
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Example 4
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G1: Avoid static loads and fixed work postures
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Static load increases systolic and diastolic
blood pressure.
Metabolic wastes accumulate in the muscles.
Consider increasing recovery time.
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Static loading
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Standing
 Shoes
affect center of gravity and forward bending
moment.
 Hard floors cause standing fatigue and increase
heart rate.
 Have hips parallel to the floor.
 Provide bar rail to vary work posture.
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Static loading
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Falls
 Slips
and falls are a major cause
of unintentional injury deaths and
have annual direct cost/capita of
$50–400.
 Causes of falls:
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Slips: unexpected horizontal foot
movement
Trips: restriction of foot movement
Stepping-on-air: unexpected vertical
foot movement
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Static loading
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Solutions for Falls
 Prevent
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Use well-designed ladders, scaffolds, and ramps
properly.
Provide safe steps.
Use the three-contact rule.
Provide good friction and reduce lubricants.
 Reduce
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the fall:
the consequences of the fall:
Interrupt the fall.
Soften the impact.
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Static loading
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Head Weight
 The
head weighs about the same as a bowling
ball.
 Keep the line of sight below the horizontal.
 Maintain forward head tilt of 10º-15º
 Avoid backward and sideward tilts.
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Source: Boeing Company, http://www.boeing.com/aboutus/environment/lead_ergo.htm
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Static loading
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Hands/Arms
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arm weighs about 4.4 kg.
 Avoid using the hand to hold up a tool or work
piece.
 Avoid working with elevated hands.
 Support the arms on the work surface or chair
arms.
 Consider using magnification.
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G2: Reduce musculoskeletal disorders
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Set the work height at 50 mm below the
elbow.
Don’t bend your wrist.
Don’t lift your elbow.
Don’t reach behind your back.
Follow guidelines for hand and arm motions.
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Source: Boeing Company, http://www.boeing.com/aboutus/environment/lead_ergo.htm
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G3: Set the work height at 50 mm below
the elbow
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Work height is defined in terms of
elbow height.
Optimum height is slightly below
the elbow.
Optimum height from the elbow is
the same for sitting and standing.
Work height is not table height.
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VDT workstations
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Key items: screen, keyboard, document, eyes,
hands
Workstation furniture must be adjustable.
Locate the primary visual element first: ahead of
the eye, perpendicular to the line of sight.
Train the operator in adjusting the equipment.
Provide a wrist rest.
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VDT workstations
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G4: Furnish every employee with an
adjustable chair
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The cost of an adjustable chair is very low compared
to labor cost.
Allow users to try chairs in their specific jobs.
Buy chairs that are easily adjustable.
Train people in proper adjustment.
Chair Design
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Seats
Backrests
Armrests
Legs/pedestals
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Examples
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G5:Use the feet as well as the hands
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The leg is slower and less dexterous than the
hands.
The legs can provide 3 times the power of the
arms.
Use pedals for power and control.
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G6: Use gravity; don’t oppose it
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Make movements horizontal or downward;
avoid lifting.
Consider using the weight of the body to
increase mechanical force.
Use gravity to move material to the work.
Use gravity as a fixture.
Use gravity in feeding and disposal.
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G7:Conserve momentum
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Avoid unnecessary acceleration and
deceleration.
Use circular motion for stirring and polishing.
Follow through in disposal motions.
Eliminate grasping motions by providing lips,
rolled edges, and holes.
Avoid transporting weight in the hand.
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G8:Use 2-hand motions rather than
1-hand motions
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Cranking with 2 arms is 25% more efficient
than with one.
Using 2 hands is more productive despite
taking more time and effort.
Don’t use the hand as a fixture.
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G9: Use parallel motions for eye control
of 2-hand motions
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Minimize the degree of spread rather than worry about
symmetry.
Estimate the cost of eye control with predetermined time
systems.
Parallel vs symmetrical motions
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Parallel motions
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• Shoulder moves
• Easy eye travel
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Symmetrical motions
• Shoulder steady
• Difficult eye control
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G10:Use rowing motions for 2-hand
motions
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Alternation causes movement of the shoulder
and twisting of the torso.
Alternation causes higher heart rates.
Rowing motions are more efficient and provide
greater power.
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G11:Pivot motions about the elbow
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Motion time is minimized with motion about
the elbow.
Cross-body movements are more accurate
than those about the elbow.
Physiological cost is lower for movements
about the elbow.
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G12:Use the preferred hand
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The dominant hand is:
 10%
faster for reach-type motions
 More accurate than the non-dominant
 More exposed to cumulative trauma
 5% to 10% stronger
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Work should arrive from the operator’s
preferred side and leave from the nonpreferred side.
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G13: Keep arm motions in the normal
work area
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Avoid long benches.
Use swingarms and lazy Susans.
For high use, keep it close.
Remember the arm pivots on the shoulder,
not the nose.
The shoulder is very sensitive to small
changes in workplace layout.
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“Windshield Wiper” Pattern
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G14: Let the small person reach; let the
large person fit
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Design so most of the user population can use the
design.
Jobs must be designed for both sexes.
Multiperson use of equipment and stations is
becoming more common.
Civilian industrial population data are not the same as
military data.
International populations be a consideration.
The proportion to exclude depends on the seriousness
of designing people out and the cost of including more
people.
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Ways to exclude few
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One size fits all
Multiple sizes
Adjustability
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