Ech 5511 ergonomic control
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Transcript of Ech 5511 ergonomic control
Slide 1Semester 2 2011/2012
INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS
Slide 2Semester 2 2011/2012
Ergonomics
Slide 3Semester 2 2011/2012
Ergonomics
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.
VARIOUS AUTHORS DEFINE ERGONOMICS AS:
Slide 4Semester 2 2011/2012
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.
VARIOUS AUTHORS DEFINE ERGONOMICS AS:
Ergonomics
Slide 5Semester 2 2011/2012
The study of the interaction between the worker and the process at the workplace.
VARIOUS AUTHORS DEFINE ERGONOMICS AS:
WHAT OTHER DEFINITIONS HAVE YOU HEARD?
Ergonomics
Slide 6Semester 2 2011/2012
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.
ERGONOMICS PLAYS A ROLE IN APPROXIMATELY 50% OF ALL WORKPLACE INJURIES. ERGONOMICS WILL HELP:
Ergonomics
Slide 7Semester 2 2011/2012
“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 BackH. Duane Saunders, MSPTby Educational Opportunities
Ergonomics
Slide 8Semester 2 2011/2012
Historical progression of WMSDs (Work related Musculoskeletel disorders)
Slide 9Semester 2 2011/2012
Ergonomics A Multi-disciplinary Approach
THINK ABOUT THE NUMBER OF WAYS ERGONOMICS
IMPACTS OUR DAILY LIFE!
Slide 10Semester 2 2011/2012
The science of ergonomics is critically important in the
continuing development of the
AUTOMOBILE!
FOR EXAMPLE!
Ergonomics A Multi-disciplinary Approach
Slide 11Semester 2 2011/2012
Economics Sociology Physiology Psychology Biomechanics Physical Sciences Management Philosophies Engineering, Industrial Design Safety & Health, Human Factors Engineering
THE FOLLOWING DISCIPLINES HAVE PLAYED A ROLE IN DEVELOPMENT OF THE AUTOMOBILE:
Ergonomics A Multi-disciplinary Approach
Slide 12Semester 2 2011/2012
Program Implementation
Personal Interest Dedication Management Commitment
IMPLEMENTATION OF AN ERGONOMIC PROGRAM REQUIRES:
NOTE:UNDERSTANDING AND SUPPORT FROM THE WORK FORCE ISESSENTIAL, WITHOUT IT THE PROGRAM WILL FAIL!
Slide 13Semester 2 2011/2012
Typical 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) reduction
APPLICATIONS
Slide 14Semester 2 2011/2012
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 Aprons
Industrial Hygiene And Ergonomic Controls
Slide 15Semester 2 2011/2012
Source of ergonomic hazards
1. The work itself2. The workstation3. Workpiece / tools4. Working environment
Slide 16Semester 2 2011/2012
INAPPROPRIATE
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.
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 Overexertion
Industrial Hygiene And Ergonomic Controls
Slide 17Semester 2 2011/2012
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.
Industrial Hygiene And Ergonomic Controls
Slide 18Semester 2 2011/2012
TANGIBLE INDICATORS: Accident Records Production Records Personnel Records Employee Surveys
Industrial Hygiene And Ergonomic Controls
Slide 19Semester 2 2011/2012
WORKSITE ANALYSISContinued
FRONT BACK
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?
Slide 20Semester 2 2011/2012
WHAT TANGIBLE INDICATORS
WOULD BE MOST USEFUL TO YOU?
INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS
Slide 21Semester 2 2011/2012
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.
(NUMBER OF NEW CASES (200,000 WORK HRS*) PER FACILITY
NUMBER OF HOURS WORKED/FACILITY/YR
INCIDENCE RATE
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.
INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS
Slide 22Semester 2 2011/2012
• 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?
IR =2 X 200,000100 X (50 X 40 hrs)
IR =400,000200,000
IR = 2 CASES OF CARPAL TUNNEL PER 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.
INDUSTRIAL HYGIENE AND ERGONOMIC CONTROLS
Slide 23Semester 2 2011/2012
ANTHROPOMETRY
ANTHROPOMETRY:
The technology of measuring and quantifying various human physical traits such as size, weight, proportion, mobility and strength.
Slide 24Semester 2 2011/2012
Engineering Anthropometry:
The application of anthropometric data to equipment, workplace and job design to enhance the efficiency, safety and comfort of the operator.
Anthropometry
Slide 25Semester 2 2011/2012
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.
Slide 26Semester 2 2011/2012
The relative sizes of different percentile humans.
Anthropometric Measurements
Slide 27Semester 2 2011/2012
• 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.
Anthropometric Measurements
Slide 28Semester 2 2011/2012
Common Ranges Of Measurements (For Office
Furniture Design.
Slide 29Semester 2 2011/2012
Slide 30Semester 2 2011/2012
Common ranges of measurementsused in office furniture design.
Slide 31Semester 2 2011/2012
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• Moving
Slide 32Semester 2 2011/2012
StandingDesk height for a standing operator can range from 28 - 43“ (Grandjean, 1997) depending on whether the desk is for precision, light, or heavy work.
Slide 33Semester 2 2011/2012
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.)
Slide 34Semester 2 2011/2012
Sitting
Slide 35Semester 2 2011/2012
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.
Slide 36Semester 2 2011/2012
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.
Slide 37Semester 2 2011/2012
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 width
Slide 38Semester 2 2011/2012
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.
Slide 39Semester 2 2011/2012
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.
Slide 40Semester 2 2011/2012
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.
Slide 41Semester 2 2011/2012
Neutral and awkward wrist postures
Slide 42Semester 2 2011/2012
Neutral and awkward elbow postures
Slide 43Semester 2 2011/2012
Neutral and awkward shoulder postures
Slide 44Semester 2 2011/2012
Neutral and awkward back postures
Slide 45Semester 2 2011/2012
Wrist posture with the keyboard placed at different positions, including flat, positive, and negative tilt
Slide 46Semester 2 2011/2012
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 dynamometer
Slide 47Semester 2 2011/2012
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.
Slide 48Semester 2 2011/2012
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.
Endplate fractures usually occur through repeated loading, by a process known as fatigue failure
Slide 49Semester 2 2011/2012
Moment Arms And Lifting
Principles • Reduce the weight of the object being lifted. • Keep loads close to the body when lifting.
Slide 50Semester 2 2011/2012
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.
Moment Arms And Lifting
Slide 51Semester 2 2011/2012
Ergonomic Risk Factors
PERSONAL RISK FACTORS
1. Age2. Gender3. Attitude4. Training5. Strength6. Work Method7. Anthropometry
Slide 52Semester 2 2011/2012
Ergonomic Risk Factors
JOB RISK FACTORS
1. Weight of load2. Location/size of load3. Frequency of the Task4. Duration and pace of cycle5. Stability of load6. Coupling of load7. Travel distances of worker8. Reach distances of worker9. Symmetry between worker and the object
held
Slide 53Semester 2 2011/2012
10. Static work posture a) Standing b) Sitting
11. Work platforms or stairs12. 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)
JOB RISK FACTORS
Ergonomic Risk Factors
Slide 54Semester 2 2011/2012
15. Environmenta) 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/vibrationa) Frequency very importantb) Can amplify through the body
JOB RISK FACTORS
Ergonomic Risk Factors
Slide 55Semester 2 2011/2012
WHAT ARE THE PRIMARY RISK
FACTORS ASSOCIATED WITH
YOUR JOB?
Ergonomic Risk Factors
Slide 56Semester 2 2011/2012
Job And Task Analysis
UNIT LOADS:
DEFINED AS:The unit to be moved or handled at any one time.
THE CONTAINER, CARRIER, OR SUPPORT USEDTO MOVE MATERIALS MUST BE INCLUDED AS PART OF THE UNIT LOAD.
Slide 57Semester 2 2011/2012
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 exposed
Job And Task Analysis
Slide 58Semester 2 2011/2012
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 FLOOR
Job And Task Analysis
Slide 59Semester 2 2011/2012
DEFINITION OF TERMS:
Fundamental Movements or acts
- Search - Inspect- Select - Assemble- Grasp - Disassemble- Reach - Delay (unavoidable)- Move - Delay (avoidable)- Hold - Plan- Position - Rest (overcome fatigue)
“ELEMENT”
Job And Task Analysis
Slide 60Semester 2 2011/2012
“CYCLE” Example:
1. Assemble new box 2. Put bottles in box from conveyor 3. Stack boxes on pallet 4. Go to step 1
The time required to complete one sequence of tasks sub- tasks, or elements.
DEFINITION OF TERMS:
Job And Task Analysis
Slide 61Semester 2 2011/2012
TASK ANALYSIS
Identify the job to study
Collect the data
Evaluate the data
Formulate control measures
Job And Task Analysis
Slide 62Semester 2 2011/2012
IDENTIFYING THE JOB TO STUDY
Accident investigations
Accident statistics
Complaints & operator feedback
Production bottlenecks, high errors
High employee turnover jobs
Job And Task Analysis
Slide 63Semester 2 2011/2012
COLLECTING THE DATA
Direct observation
Video tape
Action photographs
Documentary accounts
Accident statistics
Job And Task Analysis
Slide 64Semester 2 2011/2012
EVALUATING THE DATA
Task description
Sub-task description
Element description
Risk factor/hazard identification
Job And Task Analysis
Slide 65Semester 2 2011/2012
FORMULATING CONTROL MEASURES
Application of ergonomic principles
Corrective action for non-compliance
Eliminate or reduce exposure
Job And Task Analysis
Slide 66Semester 2 2011/2012
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 Stressor
Job And Task Analysis
Slide 67Semester 2 2011/2012
Job And Work Station Design
GOOD JOB DESIGN
REDUCES Discomfort, Fatigue, Aches & PainsInjuries & Illnesses, Work Restrictions
AVOIDS Absenteeism, Turnover, Complaints,Poor Performance, Poor Vigilance
ABATES Accidents, Production Problems,Poor Quality, Scrap/Rework
Slide 68Semester 2 2011/2012
GOOD JOB DESIGN
PREVENTS Economic Loss, Loss in Earning Power,Loss in Quality of Life, Pain & Suffering
PREVENTS Economic Loss, Loss in Expertise,Compensation Costs, Damaged Goods& Equipment
EMPLOYEE:
EMPLOYER:
Job And Work Station Design
Slide 69Semester 2 2011/2012
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 Legs
DESIGN CONSIDERATIONS
Job And Work Station Design
Slide 70Semester 2 2011/2012
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 Trauma
DESIGN CONSIDERATIONS
Job And Work Station Design
Slide 71Semester 2 2011/2012
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!
THE BOTTOM LINE
Job And Work Station Design
Slide 72Semester 2 2011/2012
WHAT ADDITIONAL DESIGN
CONSIDERATIONS CAN YOU THINK OF
FOR WORK STATIONS?
Job And Work Station Design
Slide 73Semester 2 2011/2012
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.
DESIGN CONSIDERATIONS
Job And Work Station Design
Slide 74Semester 2 2011/2012
REMEMBER
A TOOL WHICH IS CALLED AN
“ERGONOMIC TOOL”IS ONLY AN ERGONOMIC TOOL
WHEN IT IS USED FOR ITS INTENDED PURPOSE
Job And Work Station Design
Slide 75Semester 2 2011/2012
Tool Design And Selection
CONSIDERATIONS
STRAIGHT WRIST
FIRM GRIP
WEIGHT
SAFE BALANCE
VIBRATION
TORQUE
PINCHPOINTS
Slide 76Semester 2 2011/2012
Tools come in endless variety, the next few slides provide some considerations to think about.
Tool Design And Selection
Slide 77Semester 2 2011/2012
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 thickness
Tool Design And Selection
Slide 78Semester 2 2011/2012
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.
Slide 79Semester 2 2011/2012
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!
Tool Design And Selection
Slide 80Semester 2 2011/2012
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 posture
Slide 81Semester 2 2011/2012
GUARDING CONSIDERATIONS
Criteria consideration
Pinch points - pinch and nip points covered?
- Stopper to avoid closing fingers?
Exhaust - pointed away from hand and body?
Tool Design And Selection
Slide 82Semester 2 2011/2012
FREE HAND CONSIDERATIONS
Criteria consideration
Free hand use - jigs and fixtures to hold work
- Fixtures can even hold tool
Tool Design And Selection
Slide 83Semester 2 2011/2012
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.
Slide 84Semester 2 2011/2012
STORAGE OF TOOL BETWEEN CYCLES
Criteria consideration
Between cycles - suspend if frequently grasped or released
- Consider workstation or waist mounted holster
Tool Design And Selection
Slide 85Semester 2 2011/2012
POWER TOOLS
Criteria consideration
Center of - should be near fist Gravity - avoid nose-heavy tools Weight - support or counterbalance
if over two pounds
Tool Design And Selection
Slide 86Semester 2 2011/2012
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 fingers
Tool Design And Selection
Slide 87Semester 2 2011/2012
POWER TOOLS
Criteria consideration
Power - torque and speed should be adequate to match fastening requirements
Hose connection - swivel connection reduces “moment” created by dangling hose
Tool Design And Selection