Ech 5511 ergonomic control

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Ech 5511 ergonomic control

  1. 1. INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLSSemester 2 2011/2012 Slide 1
  2. 2. ErgonomicsSemester 2 2011/2012 Slide 2
  3. 3. Ergonomics VARIOUS AUTHORS DEFINE ERGONOMICS AS:  The study of man’s relationship with his or her workplace.  Fitting the task to the person rather than forcing him/her to adapt to the work environment.  Designing the workplace to prevent occupational injury and illness.Semester 2 2011/2012 Slide 3
  4. 4. Ergonomics VARIOUS AUTHORS DEFINE ERGONOMICS AS:  Discovering the capabilities and limitations of the human body.  The art and science that addresses workers’ job performance and well-being in relation to their job tasks, tools, equipment and environment.  The study of the relationship between people and machines or between employees and their environment.Semester 2 2011/2012 Slide 4
  5. 5. Ergonomics VARIOUS AUTHORS DEFINE ERGONOMICS AS:  The study of the interaction between the worker and the process at the workplace. WHAT OTHER DEFINITIONS HAVE YOU HEARD?Semester 2 2011/2012 Slide 5
  6. 6. Ergonomics ERGONOMICS PLAYS A ROLE IN APPROXIMATELY 50% OF ALL WORKPLACE INJURIES. ERGONOMICS WILL HELP:  Improve quality.  Improve absenteeism.  Maintain a healthier work force.  Reduce injury and illness rates.  Acceptance of high-turnover jobs.  Workers feel good about their work.  Reduce workers’ compensation costs.  Elevate OSHA compliance to a higher level of awareness.Semester 2 2011/2012 Slide 6
  7. 7. Ergonomics “It is estimated that in the United States, 97% of the money spent for medical care is directed toward treatment of an illness, injury or disability. Only 3% is spent on prevention.” Self-help Manual for your Back H. Duane Saunders, MSPT by Educational OpportunitiesSemester 2 2011/2012 Slide 7
  8. 8. Historical progression of WMSDs (Work related Musculoskeletel disorders)Semester 2 2011/2012 Slide 8
  9. 9. Ergonomics A Multi-disciplinary Approach THINK ABOUT THE NUMBER OF WAYS ERGONOMICS IMPACTS OUR DAILY LIFE!Semester 2 2011/2012 Slide 9
  10. 10. Ergonomics A Multi-disciplinary Approach FOR EXAMPLE! The science of ergonomics is critically important in the continuing development of the AUTOMOBILE!Semester 2 2011/2012 Slide 10
  11. 11. Ergonomics A Multi-disciplinary Approach THE FOLLOWING DISCIPLINES HAVE PLAYED A ROLE IN DEVELOPMENT OF THE AUTOMOBILE:  Economics  Sociology  Physiology  Psychology  Biomechanics  Physical Sciences  Management Philosophies  Engineering, Industrial Design  Safety & Health, Human Factors EngineeringSemester 2 2011/2012 Slide 11
  12. 12. Program Implementation IMPLEMENTATION OF AN ERGONOMIC PROGRAM REQUIRES:  Personal Interest  Dedication  Management Commitment NOTE: UNDERSTANDING AND SUPPORT FROM THE WORK FORCE IS ESSENTIAL, WITHOUT IT THE PROGRAM WILL FAIL!Semester 2 2011/2012 Slide 12
  13. 13. Typical Applications APPLICATIONS  Work station design  Tool selection and design  Office safety improvement  Video display terminals (VDT’s) safety  Back injury reduction and prevention  Manual material handling improvement  Cumulative trauma disorder (CTD) reductionSemester 2 2011/2012 Slide 13
  14. 14. Industrial Hygiene And Ergonomic Controls ENGINEERING CONTROLS  1st CHOICE  Work Station Design  Tool Selection and Design  Process Modification  Mechanical Assist  ADMINISTRATIVE CONTROLS  2nd CHOICE  Training Programs  Job Rotation/Enlargement  Pacing  Policy and Procedures  PERSONNEL PROTECTIVE EQUIPMENT LAST CHOICE  Gloves  Wraps  Shields  Eye Protection  Non-Slip Shoes  ApronsSemester 2 2011/2012 Slide 14
  15. 15. Source of ergonomic hazards 1. The work itself 2. The workstation 3. Workpiece / tools 4. Working environmentSemester 2 2011/2012 Slide 15
  16. 16. Industrial Hygiene And Ergonomic Controls  OCCUPATIONAL RISK FACTORS: Occupational risk factors are defined as any attribute of a job or task that we know increases the probability of injury or illness.  INAPPROPRIATE 1. Force - Including- Internal or External 2. Posture - Such as - Extreme Twisting or Bending 3. Repetition - Including- Muscle Group Overexertion 4. Insufficient Rest - Including- Muscle Group OverexertionSemester 2 2011/2012 Slide 16
  17. 17. Industrial Hygiene And Ergonomic Controls  WORKSITE ANALYSIS IS DIVIDED INTO 4 MAIN PARTS: 1. Gathering information from available sources. 2. Conducting baseline screening surveys to determine which jobs need a closer analysis. 3. Performing ergonomic job hazard analyses of those work stations with identified risk factors. 4. After implementing control measures, conducting periodic surveys and follow-up to evaluate changes.Semester 2 2011/2012 Slide 17
  18. 18. Industrial Hygiene And Ergonomic Controls TANGIBLE INDICATORS:  Accident Records  Production Records  Personnel Records  Employee SurveysSemester 2 2011/2012 Slide 18
  19. 19. WORKSITE ANALYSIS Continued SYMPTOM SURVEY 1. Note areas of pain or discomfort! 2. What do you feel is the source? 3. What environmental changes would help? 4. What other feedback can be gathered? FRONT BACKSemester 2 2011/2012 Slide 19
  20. 20. INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS WHAT TANGIBLE INDICATORS WOULD BE MOST USEFUL TO YOU?Semester 2 2011/2012 Slide 20
  21. 21. INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS INCIDENCE RATES: incidence rates for upper extremity disorders and/or back injuries should be calculated by counting the incidences of CTDs and reporting the incidences per 100 full time workers per year per facility. INCIDENCE RATE (NUMBER OF NEW CASES (200,000 WORK HRS*) PER FACILITY NUMBER OF HOURS WORKED/FACILITY/YR  200,000 = approximate annual work hours for 100 workers.  The same method should be applied to departments, production lines, or job types within each facility.Semester 2 2011/2012 Slide 21
  22. 22. INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS • SAMPLE INCIDENCE RATE CALCULATION: (Number of new cases (200,000 work hrs*) per facility Number of hours worked/facility/yr If you experienced 2 carpal tunnel cases last year, in a population of 100 employees. What is the incidence rate? 2 X 200,000 IR = 100 X (50 X 40 hrs) 400,000 IR = 2 CASES OF CARPAL TUNNEL PER IR = 200,000 100 PERSON-YEARS OF EXPOSURE * 200,000 = approximate annual work hours for 100 workers. * The same method should be applied to departments, production lines, or job types within each facility.Semester 2 2011/2012 Slide 22
  23. 23. ANTHROPOMETRY ANTHROPOMETRY: The technology of measuring and quantifying various human physical traits such as size, weight, proportion, mobility and strength.Semester 2 2011/2012 Slide 23
  24. 24. Anthropometry Engineering Anthropometry: The application of anthropometric data to equipment, workplace and job design to enhance the efficiency, safety and comfort of the operator.Semester 2 2011/2012 Slide 24
  25. 25. Anthropometric Measurements • When designing products it is important to remember that people come in many sizes and shapes. • Anthropometric data varies considerably between regional populations. • For example, Scandinavian populations tend to be taller, while Asian and Italian populations tend to be shorter.Semester 2 2011/2012 Slide 25
  26. 26. Anthropometric Measurements The relative sizes of different percentile humans.Semester 2 2011/2012 Slide 26
  27. 27. Anthropometric Measurements • It is common practice to design for the 5th percentile (5th%) female to the 95th percentile (95th%) male. • The 5th% female value for a particular dimension (e.g. Sitting height) usually represents the smallest measurement for design in a population. • Conversely, a 95th% male value may represent the largest dimension for which one is designing. • The 5th% to 95th% range accommodates approximately 90% of the population. • To design for a larger portion of the population, one might use the range from the 1st% female to the 99th% male.Semester 2 2011/2012 Slide 27
  28. 28. Common Ranges Of Measurements (For Office Furniture Design.Semester 2 2011/2012 Slide 28
  29. 29. Semester 2 2011/2012 Slide 29
  30. 30. Common ranges of measurements used in office furniture design.Semester 2 2011/2012 Slide 30
  31. 31. Common Workplace Postures There are common postures found in the office environment that can be considered when designing workplace products or space. • Standing • Sitting • Reaching • MovingSemester 2 2011/2012 Slide 31
  32. 32. Standing Desk height for a standing operator can range from 28 - 43“ (Grandjean, 1997) depending on whether the desk is for precision, light, or heavy work.Semester 2 2011/2012 Slide 32
  33. 33. Sitting • Knowing what parameters to design for while the user is seated can help increase the comfort of the user. • Common seated anthropometric measurements can be seen in slide 17 • Spine and Lumbar – Maintaining the neutral, or standing shape of the lumbar, or lower spinal area, is important for comfort and posture. – Chairs can give appropriate and correct lumbar support. – This seated lumbar support will help the spine maintain an S- shaped curve similar to the spine’s shape when standing (as seen in Figure 5.)Semester 2 2011/2012 Slide 33
  34. 34. SittingSemester 2 2011/2012 Slide 34
  35. 35. Sitting • Posture – Correct seated posture is a continual debate with ergonomic professionals. – Some say that users need to have a 90-90-90 degree placement for the elbow, hip, and knee joints, respectively. – Others feel that a variation in this placement is better, as long as it does not lead to slouching or hunching over. – A good seated posture is one that is comfortable and does not put a lot of stress or strain on the user’s buttocks, back, or arm muscles, and allows the user’s feet to be on the floor.Semester 2 2011/2012 Slide 35
  36. 36. Reaching • The workstation, and parts that go with workstations (such as overhead storage and pedestals), should allow the majority of movement of the user’s body joints within healthy zones. • When designing products, consider how much individuals will have to reach in order to minimize awkward or unhealthy positions.Semester 2 2011/2012 Slide 36
  37. 37. Moving • Users will move around in their environment to file papers, answer a phone, or stretch. • An occasional break from sitting is encouraged because it helps to stimulate muscles, and increases blood flow, which decreases fatigue. • The space in a cubicle or desk area should allow the chair to move around easily. • Also, a wheelchair may need to turn around or move in the office space, requiring a 60" diameter turning radius and at least 36" of passage widthSemester 2 2011/2012 Slide 37
  38. 38. Moving • Chairs and other devices in the workspace can allow the user to easily get up and move around without having to move armrests, adjust other chair settings, or put undue stress on the body.Semester 2 2011/2012 Slide 38
  39. 39. Ranges of motion (ROM) for different joints. • Zone 0 (Green Zone) Preferred zone for most movements. Puts minimal stress on muscles and joints. • Zone 1 (Yellow Zone) Preferred zone for most movements. Puts minimal stress on muscles and joints. • Zone 2 (Red Zone) More extreme position for limbs. Puts greater strain on muscles and joints. • Zone 3 (Beyond Red Zone) Most extreme positions for limbs, should be avoided if possible, especially with heavy lifting or repetitive tasks.Semester 2 2011/2012 Slide 39
  40. 40. Repetitive Motions • If repetitive tasks are necessary, minimizing the number of continuous movements can help reduce the risk of injuries. • There is no specific number for minimum daily repetitions. • The factors affecting repetitive tasks include user’s muscle strength, amount of force required, and type of task. • Decreasing the amount of force required to perform a task will also lower the risk of pain and musculoskeletal disorders.Semester 2 2011/2012 Slide 40
  41. 41. Neutral and awkward wrist posturesSemester 2 2011/2012 Slide 41
  42. 42. Neutral and awkward elbow posturesSemester 2 2011/2012 Slide 42
  43. 43. Neutral and awkward shoulder posturesSemester 2 2011/2012 Slide 43
  44. 44. Neutral and awkward back posturesSemester 2 2011/2012 Slide 44
  45. 45. Wrist posture with the keyboard placed at different positions, including flat, positive, and negative tiltSemester 2 2011/2012 Slide 45
  46. 46. When body joints are in awkward postures, maximum force produced decreases. Muscle fatigue will occur earlier when working in an awkward posture instead of a neutral posture. Hand dynamometerSemester 2 2011/2012 Slide 46
  47. 47. Pinch grip & power grip  A power grip curls the fingers toward the palm; a pinch grip presses the thumb against the fingers of the hand or an object, and does not involve the palm.  The amount of force that can be generated depends on the type of grip and the width of the grip.Semester 2 2011/2012 Slide 47
  48. 48. Fatigue Failure Endplate fractures usually occur through repeated loading, by a process known as fatigue failure The vertebrae of the back can have multiple sub-failures that are not visible but can result in complete failure over time. The number of cycles that lead to failure of the vertebrae varies across the population.Semester 2 2011/2012 Slide 48
  49. 49. Moment Arms And Lifting Principles • Reduce the weight of the object being lifted. • Keep loads close to the body when lifting.Semester 2 2011/2012 Slide 49
  50. 50. Moment Arms And Lifting The length of the moment arm and weight of the object both affect the forces exerted by the lower-back muscles. The size and shape of the object lifted or carried, existence of barriers, and design of workstations are all factors that affect the moment arm of an object being lifted or carried.Semester 2 2011/2012 Slide 50
  51. 51. Ergonomic Risk Factors PERSONAL RISK FACTORS 1. Age 2. Gender 3. Attitude 4. Training 5. Strength 6. Work Method 7. AnthropometrySemester 2 2011/2012 Slide 51
  52. 52. Ergonomic Risk Factors JOB RISK FACTORS 1. Weight of load 2. Location/size of load 3. Frequency of the Task 4. Duration and pace of cycle 5. Stability of load 6. Coupling of load 7. Travel distances of worker 8. Reach distances of worker 9. Symmetry between worker and the object heldSemester 2 2011/2012 Slide 52
  53. 53. Ergonomic Risk Factors JOB RISK FACTORS 10. Static work posture a) Standing b) Sitting 11. Work platforms or stairs 12. Torso flexion (bending) a) Mild (up to 45 degrees) b) Severe (greater than 45 degrees) 13. Work heights (too high or too low) 14. Floor surfaces (wet, smooth, vibration)Semester 2 2011/2012 Slide 53
  54. 54. Ergonomic Risk Factors JOB RISK FACTORS 15. Environment a) Hot (sweat, reduced grip, fatigue) b) Cold (gloves reduce grip by as much as 30%) 16. Lighting a) posture problems (because of inability to see) 17. Noise/vibration a) Frequency very important b) Can amplify through the bodySemester 2 2011/2012 Slide 54
  55. 55. Ergonomic Risk Factors WHAT ARE THE PRIMARY RISK FACTORS ASSOCIATED WITH YOUR JOB?Semester 2 2011/2012 Slide 55
  56. 56. Job And Task Analysis UNIT LOADS: DEFINED AS: The unit to be moved or handled at any one time. THE CONTAINER, CARRIER, OR SUPPORT USED TO MOVE MATERIALS MUST BE INCLUDED AS PART OF THE UNIT LOAD.Semester 2 2011/2012 Slide 56
  57. 57. Job And Task Analysis FACTORS AFFECTING UNIT LOADS  The material to be utilized  The quantity of material to be handled  The susceptibility of the material to damage  The number of times the unit load is handled  The receiving, storing, shipping, and handling methods  The environmental conditions to which the load is exposedSemester 2 2011/2012 Slide 57
  58. 58. Job And Task Analysis DESIGNING THE UNIT LOAD  Optimize the weight of the load  Reduce the size of the load  Insure stability of the load  Optimize load coupling - HAND TO LOAD - FOOT TO FLOORSemester 2 2011/2012 Slide 58
  59. 59. Job And Task Analysis DEFINITION OF TERMS:  Fundamental Movements or acts “ELEMENT” - Search - Inspect - Select - Assemble - Grasp - Disassemble - Reach - Delay (unavoidable) - Move - Delay (avoidable) - Hold - Plan - Position - Rest (overcome fatigue)Semester 2 2011/2012 Slide 59
  60. 60. Job And Task Analysis DEFINITION OF TERMS:  The time required to complete one sequence of tasks sub- tasks, or elements. “CYCLE”  Example: 1. Assemble new box 2. Put bottles in box from conveyor 3. Stack boxes on pallet 4. Go to step 1Semester 2 2011/2012 Slide 60
  61. 61. Job And Task Analysis TASK ANALYSIS  Identify the job to study  Collect the data  Evaluate the data  Formulate control measuresSemester 2 2011/2012 Slide 61
  62. 62. Job And Task Analysis IDENTIFYING THE JOB TO STUDY  Accident investigations  Accident statistics  Complaints & operator feedback  Production bottlenecks, high errors  High employee turnover jobsSemester 2 2011/2012 Slide 62
  63. 63. Job And Task Analysis COLLECTING THE DATA  Direct observation  Video tape  Action photographs  Documentary accounts  Accident statisticsSemester 2 2011/2012 Slide 63
  64. 64. Job And Task Analysis EVALUATING THE DATA  Task description  Sub-task description  Element description  Risk factor/hazard identificationSemester 2 2011/2012 Slide 64
  65. 65. Job And Task Analysis FORMULATING CONTROL MEASURES  Application of ergonomic principles  Corrective action for non-compliance  Eliminate or reduce exposureSemester 2 2011/2012 Slide 65
  66. 66. Job And Task Analysis TASK ANALYSIS FORM  TASK DESCRIPTION - Action Being Performed  LEFT HAND - Usage  RIGHT HAND - Usage  FREQUENCY - Usually per minute  NOTES - Supporting information  POSTURE - Acceptable to extreme  FORCE - High, Medium, Low  DURATION - Length of StressorSemester 2 2011/2012 Slide 66
  67. 67. Job And Work Station Design GOOD JOB DESIGN REDUCES Discomfort, Fatigue, Aches & Pains Injuries & Illnesses, Work Restrictions AVOIDS Absenteeism, Turnover, Complaints, Poor Performance, Poor Vigilance ABATES Accidents, Production Problems, Poor Quality, Scrap/ReworkSemester 2 2011/2012 Slide 67
  68. 68. Job And Work Station Design GOOD JOB DESIGN EMPLOYEE: PREVENTS Economic Loss, Loss in Earning Power, Loss in Quality of Life, Pain & Suffering EMPLOYER: PREVENTS Economic Loss, Loss in Expertise, Compensation Costs, Damaged Goods & EquipmentSemester 2 2011/2012 Slide 68
  69. 69. Job And Work Station Design DESIGN CONSIDERATIONS  Design for the Range-of-Motion of the Worker  Design for the Field of Vision of the Worker  Design out Extreme Ranges-of-Motion  Reduce Force in Job Accomplishment  Reduce the Frequency of Motions Required  Reduce the Duration of a Specific Task  Design to Provide Adequate Support to Back, and LegsSemester 2 2011/2012 Slide 69
  70. 70. Job And Work Station Design DESIGN CONSIDERATIONS  Incorporate Adjustable Work Surfaces  Design Delivery Bins to Accommodate Various Heights  Design Delivery Bins to Accommodate Various Reaches  Design Work Platforms with Ranges-of-Movement  Incorporate the use of Mechanical or Powered Assists  Incorporate the use of Suspension Devices for Tools  Incorporate the use of Floor mats to Reduce Leg TraumaSemester 2 2011/2012 Slide 70
  71. 71. Job And Work Station Design THE BOTTOM LINE  Do not design for the average!  Do not design for yourself!  The large must be able to fit!  The small must be able to reach!  Design for a range!  Design for adjustability!Semester 2 2011/2012 Slide 71
  72. 72. Job And Work Station Design WHAT ADDITIONAL DESIGN CONSIDERATIONS CAN YOU THINK OF FOR WORK STATIONS?Semester 2 2011/2012 Slide 72
  73. 73. Job And Work Station Design DESIGN CONSIDERATIONS  Consider the Gender and Age of Users.  The Specific Use of the Tool Is Critical.  Contact Manufactures for Their Assistance.  Make Informed Decisions Before You Buy.  Don’t be Fooled by Misleading Advertising.  Any Other (than its intended) Use Negates Possibly All Benefits and May Prove to be Detrimental to an Ergonomic Program.Semester 2 2011/2012 Slide 73
  74. 74. Job And Work Station Design REMEMBER A TOOL WHICH IS CALLED AN “ERGONOMIC TOOL” IS ONLY AN ERGONOMIC TOOL WHEN IT IS USED FOR ITS INTENDED PURPOSESemester 2 2011/2012 Slide 74
  75. 75. Tool Design And Selection CONSIDERATIONS PINCHPOINTS STRAIGHT WRIST WEIGHT TORQUE VIBRATION SAFE BALANCE FIRM GRIPSemester 2 2011/2012 Slide 75
  76. 76. Tool Design And Selection  Tools come in endless variety, the next few slides provide some considerations to think about.Semester 2 2011/2012 Slide 76
  77. 77. Tool Design And Selection HANDLE CONSIDERATIONS Criteria consideration  Diameter - avoid one size fits all  Hand fit - avoid grooves and contours that cause pressure points  Handle - non-conductive Material - textured to avoid slip or twist - Consider thicknessSemester 2 2011/2012 Slide 77
  78. 78. Tools whose handles are sized and shaped to complement the hand, require less effort to use, thereby reducing the muscle fatigue that leads to discomfort.Semester 2 2011/2012 Slide 78
  79. 79. Tool Design And Selection HANDLE CONSIDERATIONS Criteria consideration  Orientation - accommodates straight wrist?  Span - not too large to grasp easily?  Grip strength - consider powered tools when operator has difficulty with forces or high repetition!Semester 2 2011/2012 Slide 79
  80. 80. Adjustability in tools, or multiple tool designs, is important because it allows for neutral postures to be adopted When selecting or purchasing a tool, consider the ability of the tool’s handle to be adjusted in multiple positions to keep the wrist in a neutral postureSemester 2 2011/2012 Slide 80
  81. 81. Tool Design And Selection GUARDING CONSIDERATIONS Criteria consideration  Pinch points - pinch and nip points covered? - Stopper to avoid closing fingers?  Exhaust - pointed away from hand and body?Semester 2 2011/2012 Slide 81
  82. 82. Tool Design And Selection FREE HAND CONSIDERATIONS Criteria consideration  Free hand use - jigs and fixtures to hold work - Fixtures can even hold toolSemester 2 2011/2012 Slide 82
  83. 83. When purchasing heavy power tools, consider features that allow the tool to be held with both hands. When operating heavy tools, take advantage of features that allow for greater control of the tool and less fatigue.Semester 2 2011/2012 Slide 83
  84. 84. Tool Design And Selection STORAGE OF TOOL BETWEEN CYCLES Criteria consideration  Between cycles - suspend if frequently grasped or released - Consider workstation or waist mounted holsterSemester 2 2011/2012 Slide 84
  85. 85. Tool Design And Selection POWER TOOLS Criteria consideration  Center of - should be near fist Gravity - avoid nose-heavy tools  Weight - support or counterbalance if over two poundsSemester 2 2011/2012 Slide 85
  86. 86. Tool Design And Selection POWER TOOLS Criteria consideration  Trigger location - placed with grip so digits don’t have to reach  Trigger tension - light enough to avoid fatigue, heavy enough to avoid accidental activation  Size - preferably large enough to span multiple fingersSemester 2 2011/2012 Slide 86
  87. 87. Tool Design And Selection POWER TOOLS Criteria consideration  Power - torque and speed should be adequate to match fastening requirements  Hose connection - swivel connection reduces “moment” created by dangling hoseSemester 2 2011/2012 Slide 87

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