Chapter 9: CRITERIA

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Chapter 9 CRITERIA

• Tradeoff of multiple criteria.
• Vague No tradeoff equations available

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CRITERIA

• Organizations
• Goals survival and growth
• Limits imposed by society, public opinion,
  religious
• moral values. Americans with
  Disabilities
• Act (ADA). Public influences, laws,
  EPA
• Employees organizational goals are affected by
• the employees goals Maslows Hierarchy
• Physiological Needs
• - Employees want to work with the least
  stress.
• - Salary pay for food, shelter and recreation.

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• Safety Needs Job Security, Peace of Mind,
• Supervisory
  Practices (Eq. Op. E)
• Seniority Rights
  
• Social Wants Job Status, Enjoyment of work,
• Social interactions, Group relations,
• Knowledge of group
  goals
• Ego Wants Reputation, Challenge, Recognition,
• Competence, Responsibility
• Self Actualization Personal fulfillment,
• Realization of potential, Liberalization
• of creativity, Maximum
  self confidence

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The 8 Foundations of W.D.
1 People vary 2 People are more educated 3
People want to say 4 The world is becoming
smaller 5 Machines are becoming more capable 6
Safety and health are more important 7 Job
specialization is increasing 8 Jobs are more
interrelated
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Foundations 6 Job Design Criteria
1 Safety is first 2 Make the machine
user-friendly 3 Reduce the percent excluded by
the design 4 Design jobs to be cognitive and
social 5 Emphasize communication 6 Use
machines to extend human performance
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Chapter 10 ANTHROPOMETRY
Anthropos (Man) Metrein (To measure)
Anthropometric data permit the designer
to design to fit the individual
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• Fit the Job to the Person
• Variability Initiative, Needs,
  Intelligence,
• Imagination, Age, Upper back
  strength
• Selection Versus Job Modification
• Example Selection
• Job Modification
• Exclude as few as possible

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POPULATION VALUES
1. Dimensions Ex. ltAmericansgt taller
ltChinese or Japanesegt 2. Strengths 1. The leg is
three times stronger than the arm 2. Direction
of force is very important 3. Right left leg 3.
Other Characteristics Weight Center of Mass can
be predicted from standard tables 4.
Anthropometric Sources
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STATISTICAL CALCULATIONS

• 1. Normal Distribution
• Predictor population mean
• Absolute variability of a population is given by
  the standard deviation
• Relative variability of a population is given by
  the coefficient of variation.
• 2. Designing for a Population / Person
• 1. Population or Person
• 2. Sizes (Shoe size example)

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Chapter 12 ERROR REDUCTION

• Error an action other than desired
• Goals Safety, Productivity, Operator
  Satisfaction
• Error Costs lost in production to death of
  employee
• Cost Reduction Pareto chart concept
• Types of Errors
• Slip, Mistakes Or Omission, Commission
• Type I Error alpha risk or producers risk)
• Type II Error beta risk or consumers risk)

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ERRORS ANALYSIS TECHNIQUES
Checklists - Decision structure tables Fish
Diagram - Fault trees Error Reduction
Guidelines Planning Guideline 1 Get enough
information Guideline 2 Ensure information is
understood Guideline 3 Proper equipment/
procedures/skill Guideline 4 Don't
forget Guideline 5 Simplify the task
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ERRORS ANALYSIS TECHNIQUES
Execution Guideline 6 Allow enough
time Guideline 7 Have sufficient motivation /
attention Allow for Errors Guideline 8 Give
immediate feedback on errors SPC Guideline 9
Improve error detectability Guideline 10
Minimize consequences of errors
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Ch-13 MACRO ERGONOMICS
Plan the Work ..then..Work the Plan
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Plan the Work, Then Work the Plan

Reward Results Carrots, Sticks, , Non , etc
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Optimize System Availability (of what ?)

• Meantime Between
  Failures (MTBF)
• Availability
• MTBF Time to Repair (MTR)
• Increase Reliability (MTBF)
• Consider Series vs Parallel Arrangements
• Rseries R1 R2 Rparallel 1 - U1 U2
• Unreliability U1 1 - R1 U1 1
  - R2
• Increase Maintainability Decrease MTR
  (downtime)
• Make Loss of Availability Less Costly

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Optimize System Availability (of what ?)

• MTR Fault detection time Fault location
  time
• Logistics time (parts) Repair
  time
• Make Loss of Availability Less Costly
• Minimize Idle Capacity
• Fixed Costs
• - Problem Annual Cost of many machines
• and personnel varies little with
  output
• - Solutions Operate more hr/yr, Use Pools
• Revise Schedules, Encourage
  Off-Peak Use

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Minimize Idle Capacity

• Variable Costs
• - Problem Keep some parts of the team busier
• Assoc. Costs
• - Solutions
• - Duplicate Components
• - Idle Low-Cost Components
• - Not On on One (man-machine)
• Use Filler Jobs or Filler People
• Adjust Workload Short Jobs, Scheduling
• Adjust Workforce Use filler labor to adjust
  W-Force

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Communicate Information

• Job Instruction Transfer the work method in
  the
• engineer mind into the
  operators mind
• Command and Control Short messages like those in
  
• computers - message
  decision - action

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Ch-14 TEMPORAL ERGONOMICS
Job Design
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OutlineFatigue - Shiftwork - GuidelinesFatigue

• Problem
• Fatigue Cardiovascular - Physiological
  -Mental
• Reduce it Maintain/increase productivity
• and Have OPTIMAL stress
• Work Hours full, part, etc, season, overtime,
  etc
• Rest Hours (Allowances)
• Body Parts
• - Cardiovascular System
• - Skeletal-Muscular System Work Rests

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Fatigue

• Body Parts The Brain
• - Stimulation
• - Concentration and Attention
• Sleep / Biological Clock
• Environmental Simulation Lights, AC, Music
• Shiftwork
• Extent Shits are economic
• Problems Economic, Social (Afternoon Events -
• weekends), Health / Safety
• Criteria Recommendations
• Plans 5 or 7 day

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Guidelines Problem is insufficient rest

1) Have a Work Scheduling Policy 2) Optimize
Stimulation During Work 3) Minimize the Fatigue
Dose 4) Use Work Breaks 5) Use Frequent Short
Breaks 6) Maximize the Recovery Rate 7)
Increase the Recovery / Work Ratio Problem
Insufficient time to recover Solution
Increase recovery time or
Decrease work time
WORTH OF RECOVERY
BREAK LENGTH
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Ch-16 WORKSTATION DESIGN
14 Guidelines
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I) Avoid Static Loads and Fixed Work Postures
Cardiovascular Effects

• Sitting
• Head / Neck
• Hands / Arms

• Standing
• Falls

II) Reduce Cumulative Trauma Disorders
III) Set Work Height 50mm Below Elbow

• Optimum Height
• Soluton Techniques( Adjustments)

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IV) Furnish Every Employee with an
Adjustable Chair

• Justification / Selection
• Chair Design Seats, Backrests, Armrests,
• Legs / Pedestal
• Non-Chair Alternatives
• Seating Posture Variability

V) Use the Feet as Well as the Hands
Power and Control
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VII) Conserve Momentum
VI) Use Gravity

Dont Oppose It
Body Work

• Stirring and Polishing Motions Baking,
  Polishing
• Disposal Motions Improve performance, minimize
• Acceleration/Deceleration deviations
• Grasping Motions Improve grasping can Min.
  Acel/Decel
• Transport Motions Extra time 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
• Two hands take more effort and time
• Holding A part with 1 hand Use a Clamp
  Saves time

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

• Arms Motions
• Eyes fixation As few close as possible MTM
• Bycicle has Max. Power if pedals are not 180

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XI) Pivot Motions About The Elbow
X) Use Rowing Motions for 2-Hand Mtns.

• Horizontal Moves Direction at a Hight
• TIME Elbow pivoting lt cross-body moves

XII) Use The Preferred Hand

• Dominant Hand vs Non
• 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
• X ECcos? CPcos(65 73/90) ?
• Y ECsin? CPsin(65 73/90) ?
• EC Elbow Shoulder Projection Distance
• CP Elbow-End of thumb Distance
• ? Forms arc DC At D ? 0 C ?
  0
• Reach at All Heights Sitting or Standing ?
• Arm pivoting Elbow vs Shoulder
• Examples Circuit Board, Car Door Assembly line

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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, Multiperson
  
• (WAFFLE House) Civilian vs Military
• All vs well fitted International Workers,
  etc.
• Percent to Exclude
• - Lower Percentiles (short or weak)
• - Upper Percentiles (tall)
• - Both Lower Upper (Low High IQ)

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CHAPTER 17 Cumulative Trauma
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Problem
Safety physical agents Toxicology Effect of
chemicals on body Cumulative Trauma Disorders
(CTD) effects on
nerves, muscles, joints, and ligaments Cumulati
ve Trauma Disorders (CTD) (or repetitive strain,
occupational overuse syndrome, work-related
musculoskeletal disorders) GOAL to get rid of
strain and pain 4 Steps (programs to reduce
CTD
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General Anatomy
Function of Muscles Tendons Ligaments
Nerves Injuries Strains (muscle or tendon
fibers) Sprains (ligaments)
General Risk Factors
Risk Factor Formula CTD A(RD)aB(JD)bC(FO)c Oc
cupational Factors RD Repetition/duration 6
factors (times) JD Joint deviation 2 factors
Goal minimize joints torque Force Observed
external   Goal reduce magnitude lever arm
of force length Vibration Disrupts blood
flow, Cause mech trauma
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• Non-occupational Factors
• Trauma outside of work (exercise)
• Non-perfect body
• Anatomical - Physiological -
  Injury
• Solutions
• Three levels prevent - catch minimize CTD
• Engineering Solutions
• Administrative Solutions
• Medical/Rehabilitation

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Hand/Wrist Problem
Problem Carpal Tunnel Syndrome (CTS) (Check
notes) Risk Factors Exposure Limit
k(a)F(b)RecD Solutions
Engineering Solutions -
Repetition/duration GOAL reduce lifetime joint
use - Joint Deviation GOAL keep wrist
in neutral position - Force
Reduce Administrative
Solutions same as the general
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Shoulder/Neck/Elbow Problem

• Problem Occupational Cerviobrachial Disorder
• Upper Limb Disorder)
• Hands working above the shoulders place stress in
  shoulder muscles and in neck to support backward
  tilt of the head
• Solutions
• Engineering Solutions
• Repetition/duration
• Joint Deviation Guideline Dont lift
  your elbow
• Force
• Administrative Solutions same as general

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Back Problem
Primarily from manual material handling -
Hierarchy of low-back pain Low-back pain -
impairment disability- compensation
Back Risk Factors

• Khalil risk factors for low-back pain
• Individual physical factors
• Psychological factors
• Task demand factors
• Environmental factors

Garg Moores risk factors Personal 10
issues11 Job risk factors 8 issues
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Back Solutions
- Underuse (disc problems) - Overuse (muscle
and ligament problems) Guideline Dont reach
behind your back Problem low CTDs for lower
leg (except knee) Solutions Reduce time
pressure (knees area)
Legs
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Chapter 18Manual Material Handling
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Ch-19 HANDTOOLS
8 Guidelines
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Hand Tool Requirements
Manual hand tools enable performance of tasks
that would be difficult or impossible to perform
without the tools. Power hand tools provide
additional benefit of replacing operators
strength.

• Should perform the function for which it is
  intended
• Should be properly proportioned to the operators
  body dimensions
• Should be adjusted to the strength and work
  capacity of the operator
• Should not cause premature fatigue
• Should be adapted to the operators sensory
  capacities
• Should be inexpensive to purchase and maintain

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Problems with Poorly Designed Hand Tools

• Pinching, crushing amputation of fingers
• Entry of foreign objects into eyes
• Straining or tearing of muscle tendons
• Inflammation of hand/wrist tendon sheaths
• Back pains
• Muscle or Mental fatigue
• Long operator learning times

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Tool Guidelines

• Use special-purpose tools
• Design tools to be used by either hand
• Power with motors rather than muscles
• Use the proper grip
• Make the grip the proper size
• Make the grip surface compressible, smooth
• Consider the usage angles
• Use the appropriate muscle group

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Tool Handles

• Design goal is to maximize forces produced while
  minimizing physical stress
• When the wrist deviates from neutral, the amount
  of stress on nerves and tissues increases
  significantly
• Premature fatigue can be minimized with the
  proper tools