Chapter 6: Value Engineering

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Ch-16 WORKSTATION DESIGN
14 Guidelines
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Outline

• Avoid Static Loads and Fixed Work Postures
• Reduce Cumulative Trauma Disorders (CTD)
• Set Work Height at 50mm Below the Elbow
• Furnish Employees with Adjustable Chair
• Use the Feet as well as the Hands
• Dont Oppose Gravity Use it.
• Conserve Momentum

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Outline (cont.)

• Use Two-Hand not One-Hand Motions
• Use Parallel Motions for Eye Control of 2-Hand
• Use Rowing Motions for Two-Hand Motions
• Pivot Motions About the Elbow
• Use the Preferred Hand
• Keep Arms in the Normal Work Area
• Let the Small Woman Reach the Large Man Fit

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I) Avoid Static Loads and Fixed Work Postures
Cardiovascular Effects

• Standing
• - Anatomy
• - Physiology
• - Shoes
• - Floors
• Falls
• - Problem
• - Causes
• - Solutions

• Sitting
• Head / Neck
• Hands / Arms

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Avoid Static Postures

• Employees should be encouraged to wear proper
  shoes for work req. lots of standing
• Workstations should be equipped with mats
• Jobs need to be designed to allow the
  three-contact rule for climbing stairs, or better
  yet, use a ramp
• Make sure walking surfaces prevent slips falls
• Keep the line of sight below horizontal
• Keep arm position low

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II) Reduce Cumulative Trauma Disorders

See Table 16.4
III) Set Work Height 50mm Below Elbow

• Optimum Height
• - Manipulative Work 50mm below elbow
• - Applies when sitting or standing
• Solution Techniques
• - Change Machine Height
• - Adjust Elbow Height
• - Adjust Work Height on Machine

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IV) Furnish Every Employee with an
Adjustable Chair

• Justification / Selection
• Chair Design
• Non-Chair Alternatives
• Seating Posture Variability

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Chair Design Considerations

• seat height from floor
• seat length
• seat width
• slope of seat
• seat shape
• position of backrest
• molded chair back position curvature
• clearance of feet and calves under chair

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V) Use the Feet as Well as the Hands

• Power
• Control

VI) Use Gravity
Dont Oppose It

• Body
• Work

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Use the Foot when Possible

• Consider adding foot control pedals instead of
  only hand controls, but only on seated jobs
• Legs have more strength
• Feet move slower than hands
• Gravity can help here too

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VII) Conserve Momentum

• Stirring and Polishing Motions
• Baking, Flour Making, Polishing
• Disposal Motions
• Improve performance, minimize
• Acceleration/Deceleration deviations
• Grasping Motions
• Improve grasping can Min. Accel/Decel
• Transport Motions
• Extra time extra effort to transport weight

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VIII) Use 2-Hand Motion Not 1-Hand

• Human Power
• How much can you pull?
• Manipulative Work
• Use guides for precise locations A Hand is NOT
• a fixture. Two hands take more effort and time
• Holding
• A part with 1 hand high static load reduce
• productivity
  Use a Clamp
• Saves time SPP 4 months

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IX) Use // Motions for Eye Control of
2-Hand Motions

• Arms Motions in Opposite Symmetrical Dirs.
• should be Symmetrical
• Eyes fixation As few close as possible
• // vs symmetrical motion the MTM case

X) Use Rowing Motions for 2-Hand Mtns.

• Rather than alternating motions

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XI) Pivot Motions About The Elbow

• Horizontal Moves Direction at a Height
• Movement Speed - Accuracy - Psychological Cost
• TIME Elbow pivoting lt cross-body moves

XII) Use The Preferred Hand

• Dominant Hand 10 faster and more accurate
• Dominant Eye Your shooting Eye
• Work Flow to W.Station From Ops. Preferred
• side leaving through non-preferred
  side

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XIII) Keep Arm Motions In Work Area

• Elbow Height see Figure 16.28
• Use reaching aids or workstation cutouts to
  increase range
• Normal Work Areas see Figures 16.29 and 16.30
• Reach at All Heights see Figure 16.28
• Sitting or Standing ? Depends
• Arm pivoting Elbow vs Shoulder
• Examples Circuit Board, Car Door Assembly
  line
• Also Dont forget to leave Toe Space in
• work area design

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XIV) Let The Small Woman Reach
and the Large Mean Fit

• Design to allow most users to use the design 50
  
• In your Design Exclude as Few as Possible
• User Population
• - Women or Men Small vs Large Welding
• - Multiperson workstation WAFFLE House
• - Civilian vs Military All vs well fitted
• - International Workers
• Percent to Exclude
• - Lower Percentiles (short or weak)
• - Upper Percentiles (tall) see Figure
  16.35
• - Both Lower Upper (Low High IQ)

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