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Ergonomics lesson 4


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Production & materials management

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Ergonomics lesson 4

  1. 1. Ergonomics (Human Factors in Job Design) Prof .P.T.SRINIVASAN
  2. 2. DEFINITION <ul><li>The term “ergonomics” is derived from two Greek words: “ergon”, meaning work and “nomoi”, meaning natural laws. Ergonomists study human capabilities in relationship to work demands. </li></ul><ul><li>Ergonomics is the science of designing the job, equipment, and workplace to fit the worker. Proper ergonomic design is necessary to prevent repetitive strain injuries, which can develop over time and can lead to long-term disability. </li></ul>
  3. 3. The International Ergonomics Association defines ergonomics <ul><li>Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance. </li></ul>
  4. 4. <ul><li>Ergonomics is employed to fulfill the two goals of health and productivity. It is relevant in the design of such things as safe furniture and easy-to-use interfaces to machines. </li></ul>
  5. 5. <ul><li>Ergonomics is described as the study of relationship between Man and his working environment. It also deals with man-machine relationship. </li></ul>ERGONOMICS OR BIOMECHANICS
  6. 6. <ul><li>People cant apply large amount of physical force. </li></ul><ul><li>People cant perform rapidly simple and repetitive movements without fatigue and mistakes. </li></ul><ul><li>People cant perform complex calculations rapidly. </li></ul><ul><li>People cant do several different tasks simultaneously. </li></ul><ul><li>People cant respond rapidly to frequently changing control signals. </li></ul><ul><li>People cant store and recall large unrelated data. </li></ul><ul><li>People cant function satisfactorily in working environment where heart is beyond the normal limit. </li></ul>LIMITATIONS OF PEOPLE AS PRODUCTIVE ELEMENTS
  7. 7. <ul><li>Machines cant respond to wide range stimuli beyond predetermined limits. </li></ul><ul><li>Machines cant respond to unpredictable events. </li></ul><ul><li>Machines cant think inductively. </li></ul><ul><li>Machines cant act with flexibility. </li></ul><ul><li>Machines cant function beyond normal limits of capacity. </li></ul>LIMITATIONS OF MACHINE
  9. 9. <ul><li>MANUAL SYSTEM </li></ul><ul><li>SEMI AUTOMATIC SYSTEM </li></ul><ul><li>AUTOMATIC SYSTEM </li></ul>TYPES OF MACHINE SYSTEM
  10. 10. EXAMPLE FOR MAN-M/C SYSTEMS WASHING M/C <ul><li>MANUAL WASHING M/C(FIG(1) </li></ul><ul><li>SEMI-AUTOMATIC M/C </li></ul><ul><li>FIG(2) </li></ul><ul><li>FULLY AUTOMATIC M/C FIG(3) </li></ul>FIG(1) FIG(2) FIG(3)
  11. 11. <ul><li>Design of physical devices-Display panels, controls i.e. user friendly </li></ul><ul><li>Work environment. </li></ul><ul><li>1)Temperature and Humidity </li></ul><ul><li>2)Noise </li></ul><ul><li>3)light or illumination </li></ul><ul><li>4)color </li></ul><ul><li>5)vibration </li></ul><ul><li>Ability and motivation of operator. </li></ul>EFFICIENCY OF MAN MACHINE SYSTEM IS AFFECTED BY THE FOLLOWING
  12. 12. <ul><li>For man or women </li></ul><ul><li>Can operator sit or stand </li></ul><ul><li>Will his posture in work be satisfactorily </li></ul><ul><li>What are the controls needed? </li></ul><ul><li>What physical work will the operator do? </li></ul><ul><li>Will he need mechanical assistance. </li></ul><ul><li>What will be the ambient conditions? </li></ul><ul><li>What are the maintance requirements? </li></ul><ul><li>Will the design promote worker participation. </li></ul>QUESTIONS ASKED BY M/C DESIGNER
  13. 13. Principles of Motion Economy (a check list for motion economy and fatigue reduction) <ul><li>There are twenty-two rules </li></ul><ul><li>These can be applied to shop and office work </li></ul><ul><li>All rules are not applicable to every operation </li></ul><ul><li>But, they form the basis for improving efficiency and reducing fatigue in manual work </li></ul>
  14. 14. Principles of Motion Economy (Use of the Human Body) <ul><li>The two hands should begin and also complete their motion at the same time </li></ul><ul><li>Hands should not be idle at the same time </li></ul><ul><li>Motions of the arms should be in opposite and symmetrical directions and be made simultaneously </li></ul><ul><li>Hand motions should be confined to the lowest classification to perform the work satisfactorily </li></ul>
  15. 15. Principles of Motion Economy (Use of the Human Body) <ul><li>Momentum should be employed to assist the worker; it should be minimum to overcome muscular effort </li></ul><ul><li>Smooth continuous motions of the hands are preferable to zigzag motions </li></ul><ul><li>Ballistic movements are faster, easier, and accurate than controlled movements </li></ul>
  16. 16. Principles of Motion Economy (Use of the Human Body) <ul><li>Rhythm is essential for smooth and automatic performance of an operation; work should be arranged to permit easy and natural rhythm </li></ul>
  17. 17. Principles of Motion Economy (Arrangement of the Work Place) <ul><li>Have a definite and fixed place for all tools and materials </li></ul><ul><li>Tools, materials, and controls should be located close to and in front of the operator </li></ul><ul><li>Gravity feedbins and containers should be used to deliver materials close to the point of use </li></ul>
  18. 18. Principles of Motion Economy (Arrangement of the Work Place) <ul><li>Drop deliveries should be used whenever possible </li></ul><ul><li>Materials and tools to be located to permit the best sequence of motions </li></ul><ul><li>Provisions for adequate seeing; good illumination for visual perception </li></ul>
  19. 19. Principles of Motion Economy (Arrangement of the Work Place) <ul><li>Height of the work place and the chair should be should be arranged so that sitting and standing are easily possible </li></ul><ul><li>A chair of the type and height to permit good posture should be provided for every worker </li></ul>
  20. 20. Principles of Motion Economy (Design of Tools and Equipment) <ul><li>Hands to be relieved of all work that could be done easily by a jig, fixture, or a foot-operated device </li></ul><ul><li>Two or more tools should be combined where ever possible </li></ul><ul><li>Tools and materials should be pre-positioned where ever possible </li></ul>
  21. 21. Principles of Motion Economy (Design of Tools and Equipment) <ul><li>Where each finger performs specific movement (computer key board) the load should be distributed in accordance with the inherent capabilities of the fingers </li></ul><ul><li>Handles of screwdrivers, cranks should have sufficient hand space ; for light assembly work, screwdriver handle to be shaped such that it is smaller at the bottom then at the top </li></ul>
  22. 22. Principles of Motion Economy (Design of Tools and Equipment) <ul><li>Levers, crossbars, and hand wheels to be located such that the operator can manipulate them with least change in body position and with greatest mechanical advantage </li></ul>
  23. 23. <ul><li>Body Segment Classes </li></ul><ul><li>Use motions with the lowest feasible class </li></ul>class Pivot point Body members Five Trunk torso Upper/fore arm, wrist & fingers Four Shoulder Upper/fore arm, wrist & fingers Three Elbow Forearm, wrist & fingers Two Wrist Hand & fingers One Knuckle fingers
  24. 24. BODY MECHANICS <ul><li>Use the largest joints & muscles to do the job </li></ul><ul><li>Use 2 hands to lift rather than one, even with light objects and tasks. </li></ul><ul><li>Avoid lifting with the forearm in full pronation (palm down) or supination (palm up) </li></ul><ul><li>Slide or push & pull objects instead of lifting </li></ul><ul><li>Keep reaching to a minimum </li></ul><ul><li>Carry objects close to body at waist level </li></ul>
  25. 25. Correct & Incorrect Techniques
  26. 26.
  27. 27. Working Environment <ul><li>The following factors should be considered: </li></ul><ul><li>Temperature &Humidity </li></ul><ul><li>Noise </li></ul><ul><li>Illumination </li></ul><ul><li>Colour </li></ul><ul><li>Vibration </li></ul>
  28. 28. Temperature & Humidity <ul><li>Efficiency of employees performing physical works decreases when temperature increases beyond 80 degree fahernheit </li></ul><ul><li>Workers not performing physical works tend to become less efficient at temperatures above 90 degrees fahrenheit </li></ul>
  29. 29. <ul><li>During cold season, the work environment should have heating facility </li></ul><ul><li>Air conditioning office environment reduces fatigue and errors </li></ul>Temperature & Humidity
  30. 30. <ul><li>High humidity level also affects the performance of the workers </li></ul><ul><li>If humidity is very high, then temperature above 90 degrees fahrenheit can be stifling </li></ul><ul><li>In less humid conditions workers can endure more heat </li></ul>Temperature & Humidity
  31. 31. <ul><li>A cold dry environment is much more comfortable than under conditions of high humidity </li></ul><ul><li>In production areas it is difficult to control humidity but not so in office areas </li></ul>Temperature & Humidity
  32. 32. Noise <ul><li>Is the result of variations in air pressure </li></ul><ul><li>May result from human speech, machine operation, vibrations, and reverberation </li></ul><ul><li>Employees have the ability to adapt to noisy environment within reasonable limits </li></ul><ul><li>Higher noise levels are annoying and painful </li></ul>
  33. 33. Noise <ul><li>Exposing employees to higher noise levels may impair their power of hearing </li></ul><ul><li>Could be reduced by replacing or adjusting moving parts, frequent lubrication, maintenance, installing special devises – carpets, curtains </li></ul><ul><li>Better to isolate noisy machines in separate buildings </li></ul>
  34. 34. <ul><li>1.NOISE - noise is unwanted sound. It is a pollutant and a hazard to human health and hearing. Noise in our environment affects physical heath. Noise also has psychological and social implications and affects our well being and quality of life.Noise can be reduced by lubrication of m/c, Drapes and ceiling tiles are used to absorb unwanted sound and eliminate echoes and mufflers are used to reduce noise. </li></ul><ul><li>Painful </li></ul><ul><li>150 dB = rock music peak </li></ul><ul><li>140 dB = firearms, air raid siren, jet engine </li></ul><ul><li>130 dB = jackhammer </li></ul><ul><li>120 dB = jet plane take-off, amplified rock music at 4-6 ft., car stereo, band practice </li></ul><ul><li>Extremely Loud </li></ul><ul><li>110 dB = rock music, model airplane </li></ul><ul><li>106 dB = timpani and bass drum rolls </li></ul><ul><li>100 dB = snowmobile, chain saw, pneumatic drill </li></ul><ul><li>90 dB = lawnmower, shop tools, truck traffic, subway </li></ul><ul><li>Very Loud </li></ul><ul><li>80 dB = alarm clock, busy street </li></ul><ul><li>70 dB = busy traffic, vacuum cleaner </li></ul><ul><li>60 dB = conversation, dishwasher </li></ul><ul><li>Moderate </li></ul><ul><li>50 dB = moderate rainfall </li></ul><ul><li>40 dB = quiet room </li></ul><ul><li>Faint </li></ul><ul><li>30 dB = whisper, quiet library </li></ul>
  35. 35. Noise <ul><li>Excessive noise may increase staff stress and fatigue. General noise may be reduced by floor carpeting and by locating office areas away from sources of external noise. The recommended decibel range for office work is 55 to 65 dBA. </li></ul><ul><li>Hard surfaces such as glass walls or white boards will act to increase the reflection of noise. </li></ul><ul><li>Telephone or other conversations can be distracting in open plan offices. Sound absorbing barriers may be considered if such noise is a problem. </li></ul><ul><li>Some office groups follow their own &quot;low noise rules&quot;. </li></ul><ul><li>Some office machines have high noise levels. Supervisors should ensure their location, patterns and vicinity to staff are such as to prevent problems. </li></ul>
  36. 36. Illumination <ul><li>Provide adequate light to perform </li></ul><ul><li>Various lighting intensities have been recommended for different types of jobs </li></ul><ul><li>Lower illumination levels cause fatigue and error </li></ul><ul><li>Over illumination is a strain to the eyes and leads to errors </li></ul><ul><li>Glare is another problem </li></ul>
  37. 37. <ul><li>ILLUMINATION </li></ul><ul><li>GENERAL REQUIREMENTS OF ARTIFICIAL LIGHTING .- </li></ul><ul><li>1 . Sufficient illumination should be provided for each workman irrespective of his position on the working space. </li></ul><ul><li>2. The lamps should be properly selected and so installed as to avoid or minimize strain on the eyes of the workmen. The type and size of lamp should be adapted to the particular ceiling height and class of work in question. </li></ul><ul><li>3. The lamps should be operated from sources of supply which will insure continuity of service and steadiness of light. </li></ul><ul><li>4. Adequate illumination should be provided from overhead lamps so that sharp shadows may be prevented as much as possible, and in such measure that individual lamps close to the work may be unnecessary except in special cases. </li></ul><ul><li>5. In addition to the illumination provided by overhead lamps, individual lamps should be placed close to the work if they are absolutely necessary, and in such cases the lamps should be provided with suitable opaque reflectors. </li></ul>
  38. 38. SOURCE: American journal of public health
  39. 39. GENERAL OFFICE ENVIRONMENT <ul><li>Lighting </li></ul><ul><li>In all working environments the lighting situation needs to be considered. </li></ul><ul><li>Illumination is measured in units of LUX - lumens per square metre </li></ul><ul><li>&quot;Ordinary&quot; visual tasks should be in range 300 to 400 lux [320 lux (task) and 160 lux (Background)]. </li></ul><ul><li>Options for adjusting lighting include(eg: computer) </li></ul><ul><li>Positioning of the monitor to the side of window light and/or in between overhead light sources. </li></ul><ul><li>&quot;Anti-glare&quot; Screen Filters- Where all other efforts to correct lighting have not succeeded, use of a screen filter may be necessary. </li></ul>
  40. 40. Colours <ul><li>Colours used in working environment affect the performance </li></ul><ul><li>Light colours are advisable for walls and ceiling </li></ul><ul><li>Colours have a remarkable effect on human behaviour </li></ul><ul><li>Green and Blue are cool colours </li></ul><ul><li>Red and Orange are warm colours </li></ul>
  41. 41. Colours <ul><li>Dull colours are used in machines to reduce glare </li></ul><ul><li>Light green is the favourite colour for machine manufacturers as it is attractive and relaxing </li></ul><ul><li>Colour is also used for plant safety and coding </li></ul>
  42. 42. Colours <ul><li>Fire extinguishers are painted red </li></ul><ul><li>Potential danger areas are outlined in yellow </li></ul><ul><li>Colour coding helps to distinguish between similar deices – hot water value is painted red, cold water valve is painted blue </li></ul>
  43. 43. <ul><li>Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road. </li></ul><ul><li>vibration is undesirable, wasting energy and creating unwanted sound – noise. For example, the vibration motions of engines, electric motors, or any mechanical device in operation are typically unwanted. Such vibrations can be caused by imbalances in the rotating parts, uneven friction, the meshing of gear teeth, etc. Careful designs usually minimize unwanted vibrations. </li></ul><ul><li>Vibrations can be reduced by machine balancing, machine over hauling and material selection. </li></ul><ul><li>Machine casing, ear plugs, absorption materials and dampers have to be provided to reduce vibration. </li></ul><ul><li>Vibration can be source of fatigue. </li></ul><ul><li>The most serious effect of vibration, especially in the case of machinery, is that sufficiently high alternating stresses can produce fatigue failure in machine and structural parts. Less serious effects include increased wear of parts, general malfunctioning of apparatus, and the propagation of vibration through foundations and buildings to locations where the vibration of its acoustic realization is intolerable either for human comfort or for the successful operation of sensitive measuring equipment. </li></ul>dampers VIBRATIONS
  44. 44. <ul><li>Give workers an optimum level of variety of tasks with the job. </li></ul><ul><li>Arrange diverse but interdependent tasks into one meaningful pattern. </li></ul><ul><li>Give workers an optimum length of work cycle. </li></ul><ul><li>If feasible give workers responsibility in setting quality standards along with feedback of performance. </li></ul>MAN AND TASK RELATIONSHIP FROM A SOCIOTECHNICAL PERSPECTIVE OF MAN M/C SYSTEM
  45. 45. <ul><li>Includes of auxiliary and preparatory tasks that extends scope of the job and work involvement in it. </li></ul><ul><li>Make the job tasks required sufficient skill from knowledge or effort to generate respect within the community. </li></ul><ul><li>Make the job show contribution of value to overall product or service being produced. </li></ul>CONTD
  46. 46.
  47. 47. B ASIC P RINCIPLES OF A CCIDENT P REVENTION <ul><li>I ndustrial Safety means freedom from accidents happening in an industry. </li></ul><ul><li>Accident means an unplanned, unexpected event, which may or may not result into an injury. </li></ul>
  52. 52. CHAIN OF EVENTS <ul><li>Injury </li></ul>Accident Unsafe acts Unsafe condition HUMAN FAILURE
  53. 53. CAUSES OF AN ACCIDENT <ul><li>Unsafe conditions </li></ul><ul><li>The major unsafe conditions are as below </li></ul><ul><li>Improper guarding ,un-guarded </li></ul><ul><li>Defective tools </li></ul><ul><li>Slippery floors, work places </li></ul><ul><li>Improper house keeping. </li></ul><ul><li>Maintenance </li></ul><ul><li>Material handling equipment-over head cranes, forklift </li></ul><ul><li>Layout, blind turnings, crowding of machines </li></ul>
  54. 54. <ul><li>Recklessness </li></ul><ul><li>Stubbornness </li></ul><ul><li>Slow learners </li></ul><ul><li>Shyness </li></ul><ul><li>Physical condition </li></ul><ul><li>Personal troubles </li></ul>HUMAN CHARACTERISTICS
  55. 55. THE MAJOR UNSAFE ACT ARE <ul><li>Operating without authority </li></ul><ul><li>Failure to secure or warn </li></ul><ul><li>Operating or working at unsafe speed </li></ul><ul><li>Making safety devices inoperative </li></ul><ul><li>Using unsafe equipment ,hands instead of equipment or equipments unsafely </li></ul><ul><li>Taking unsafe position or posture </li></ul><ul><li>Failure to use personal protective equipment </li></ul><ul><li>Ignoring rules </li></ul><ul><li>Teasing </li></ul><ul><li>Improper handling equipments </li></ul>
  56. 56. <ul><li>NATIONAL INDUSTRIAL SAFETY DAY: </li></ul><ul><li>MARCH 4 TH </li></ul><ul><li>Gujarat is one of the leading state of the nation and has the highest number of chemical factories. </li></ul><ul><li>There Every year, a safety week is celebrated starting from 4th March being a National Safety Day, throughout the state. During these days many safety programs are arranged in different industrial estates and in large industries too. </li></ul><ul><li>All these safety programs consist of popular method of sending message of safety by displaying banners, slogans, posters and arranging competition for safety essays, safety poems and safety slogans etc. </li></ul>
  57. 57. INDUSTRIAL SAFETY DAY <ul><li>INTERNATIONAL INDUSTRIAL SAFETY DAY: APRIL 28 TH </li></ul><ul><li>Four years back on April 28 th, a national seminar on industrial safety & health vision 2020 was organized by directorate general (DG), Factory Advice and Labour Institutes (DGFASLI) Mumbai, an apex body of the ministry of labour and employment. </li></ul><ul><li>While addressing the national seminar on ’Industrial Safety and Health-Vision 2020: Challenges and Strategies’, minister for labour and employment, Oscar Fernandes announced that the year 2008 has been declared as the ’ Year of Industrial Safety and Health,’ by the government of India . </li></ul>
  58. 58. <ul><li>The occasion was special because 60 years of announcement and enforcement of the Factories Act, 1948 was observed on that day. </li></ul><ul><li>The minister suggested that lifestyle management interventions like physical exercises, yoga classes, meditation techniques and sports related activities should be carried out on a regular basis as a part of stress management. He said that these facilities should be made available in the premises of the industries as well as the colonies of the workers to ensure that all the workers can utilize them. </li></ul>
  59. 59. Thank You