Ergonomics - Atlas Copco

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HanDle DeSiGn Most screwdrivers are provided with either a straight or a pistol grip. The surface of the handle has a rough texture to prevent it from rotating in the hand due to the reaction torque when tightening. This increases the friction between the handle and the hand. When push force is required (for certain screws), a handle end- stop is recommended if a straight machine is used. However, the best choice for high push forces is the pistol grip. Straight screwdrivers usually have a lever trigger or a push-to-start function. If the tool has a reverse function, it is often controlled by a thumb-operated button. By gripping a pistol grip tool with the entire hand, the operator can cope with higher torque levels than when using straight machines. The finger-operated trigger and thumb-operated reverse function are common designs. external loaD Straight machines must be grasped tightly to counteract the reaction torque. This problem can be solved by a torque reaction arm. Self-drilling and self-tapping screws require high push force. When using screws of this type, the repetitiveness of the task must be considered. Screwdrivers are often used for assembly tasks at sitting workstations. In the sitting position, the neck and shoulder muscles can easily be overloaded, particularly when performing highly repetitive tasks. WeiGHt Screwdrivers are relatively light, low- powered tools. At a typical assembly station they are hung from balancers. These must be adjusted so that the operator does not need to use excessive force to pull the tool down. When performing highly repetitive tasks the weight of the tool may place an additional external load on the operator, but repetition should be avoided wherever possible. teMPeratUre Screwdrivers consume energy for limited periods only. Therefore low or high tempera- tures are not a problem in most applications. SHoCK reaCtion A short period of increased torque when tightening a screw will cause a straight tool to start rotating and a pistol grip tool to turn. The magnitude of the motion depends on the impulse. The fastest machine capable of generating the torque needed for the joint should always be used in order to minimize the impulse. The motion of the tool also 47
48 depends on its inertia. The same impulse will have a greater turning effect on a straight tool than on a pistol grip tool. ViBration There are two types of screwdriver. The shut-off type and the slip clutch type. Shut-off tools have very short operating cycles. The pulse from tightening with a shut-off tool cannot be regarded as a vibration. Slip clutch tools, on the other hand, continue to run until the operator releases the trigger. Operators tend to run the tools with the clutch slipping for a few seconds on each joint. This behavior will expose the operator to unnecessary vibration. noiSe These tools are often used in low noise assembly areas. Therefore, low machine noise is important to avoid disturbing workers’ conversation or enjoyment of radio broadcasts. Another reason for keeping noise levels to a minimum is the fact that an operator performing a precision task often works with his head close to the tool. A muffler is used for noise control on pneumatic tools and the exhaust air is often piped away from the machine in an exhaust hose. Electric screwdrivers normally have very low noise emissions. DUSt anD oil Dust is not created in the process and the tool is lubrication free. Electric screwdrivers can be programmed to tighten the joint to the correct torque with a minimum of reaction torque to the operator.
Page 1 and 2: Power Tool Ergonomics E V A L U A T
Page 3 and 4: Acknowledgements While doing resear
Page 5 and 6: How to get the best out of this boo
Page 7 and 8: Work with international standards I
Page 9 and 10: Good ergonomics is good economics W
Page 11 and 12: 10 SOCIOLOGY INDUSTRIAL SOCIOLOGY S
Page 13 and 14: 12 Work organization No organizatio
Page 15 and 16: 1 outside the production system, an
Page 17 and 18: 1 A seated operator usually has goo
Page 19 and 20: 1 without stretching the trunk. The
Page 21 and 22: 20 The arm sling as a preventive me
Page 23 and 24: 22 Extreme working postures in real
Page 25 and 26: 2 Working with high feed forces req
Page 27 and 28: 2 Working areas of a standing works
Page 29 and 30: 2 body is lifted or tilted, or the
Page 31 and 32: 30 The team is an important factor
Page 33 and 34: 32 Grinders Grinders and sanders ar
Page 35 and 36: 34 HanDle DeSiGn The hand grips on
Page 37 and 38: 36 DUSt anD oil Although the machin
Page 39 and 40: 38 Working environment In general,
Page 41 and 42: 40 SHoCK reaCtion Sudden changes in
Page 43 and 44: 42 practice. Sometimes the chisel h
Page 45 and 46: 44 SHoCK reaCtion These tools do no
Page 47: 46 heavy, assembly work is often hi
Page 51 and 52: 50 bolts. Unfortunately there are a
Page 53 and 54: 52 The low reaction torque in impul
Page 55 and 56: 54 the working environment A typica
Page 57 and 58: 56 Today, the angle nutrunner can b
Page 59 and 60: 58 High torque nutrunners for use w
Page 61 and 62: 60 Wheel nuts on trucks and buses a
Page 63 and 64: 62 Introduction A basic ergonomic p
Page 65 and 66: 64 Handle design The handle of a ha
Page 67 and 68: 66 Arteries Veins (superficial) Vei
Page 69 and 70: 68 Handle size Since a tool handle
Page 71 and 72: 70 However, if the texture is too c
Page 73 and 74: 72 Bibliography Chaffin, D.B. and A
Page 75 and 76: 74 Fig. 3.3 The same feed force app
Page 77 and 78: 76 Pushing and pulling Pushing a to
Page 79 and 80: 78 the object, the shape of the obj
Page 81 and 82: 80 Safety factor a 2 Frequency of t
Page 83 and 84: 82 Comments for different tool type
Page 85 and 86: 84 The trigger is either operated b
Page 87 and 88: 86 used in one handed operations. T
Page 89 and 90: 88 Weight The weight of a hand-held
Page 91 and 92: 90 stability of grip, the center of
Page 93 and 94: 92 Temperature Hand-held power tool
Page 95 and 96: 94 To ensure physical comfort durin
Page 97 and 98: 96 Score 40 30 20 10 0 Bibliography
Page 99 and 100:
98 the dynamic properties of the ma
Page 101 and 102:
100 High motor power and fast clutc
Page 103 and 104:
102 Score 40 30 20 10 0 shock react
Page 105 and 106:
104 piezo-electric crystal. When th
Page 107 and 108:
106 EN 50144 and EN 60745. Both ISO
Page 109 and 110:
108 hole of the wheel are wider tha
Page 111 and 112:
110 In the GTG 40 grinding machine,
Page 113 and 114:
112 RRH machines serves two functio
Page 115 and 116:
114 be noted that declared values b
Page 117 and 118:
116 Noise Noise was the first envir
Page 119 and 120:
118 value for 8 hours’ exposure t
Page 121 and 122:
120 We can start by looking at the
Page 123 and 124:
122 This is done with a minimum inc
Page 125 and 126:
124 microphones at a distance of 1
Page 127 and 128:
126 coated with dust or damaged by
Page 129 and 130:
128 This method has not been used b
Page 131 and 132:
130 tool cabinet. Many workplaces h
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132 lubrication. Made from a compos
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134 Grinder GTG 40 F085 The relevan
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136 were simulated by fitting a whe
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138 Drill LBB 26 EPX-060 The releva
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140 applied to the center of the dr
Page 143 and 144:
142 Chipping hammer RRF 31 The rele
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144 SHOCK REACTION There are no sho
Page 147 and 148:
146 Riveting hammer RRH 06 The rele
Page 149 and 150:
148 WEIGHT The weight is 1.3 kg, sc
Page 151 and 152:
150 Screwdriver LUM 22 PR4 The rele
Page 153 and 154:
152 This gives a score of 9. In pra
Page 155 and 156:
154 Impulse nutrunner EP9 PTX80-HR1
Page 157 and 158:
156 Due to friction in the hydrauli
Page 159 and 160:
158 Electric nutrunner ETP ST32-05-
Page 161 and 162:
160 WEIGHT The electric nutrunner i
Page 163 and 164:
162 Angle nutrunner LTV 29 R30-10 T
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164 operator equal to installed tor
Page 167 and 168:
166 Electric angle nutrunner Tensor
Page 169 and 170:
168 WEIGHT The electric nutrunner i
Page 171 and 172:
170 High torque nutrunner LTP 51 Th
Page 173 and 174:
172 Score 40 30 20 10 0 NOISE The d
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Ergonomics - Atlas Copco

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