Ergonomics - Atlas Copco

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EXTERNAL LOAD For evaluation purposes, it is assumed that the tool is being used for line assembly in the motor vehicle industry at a workstation where the tool is used on horizontal surfaces. The height is adjusted to allow a comfortable posture for counteracting the horizontal pull force from the torque reaction. The tool is used on a 50 Nm soft joint. It is operated with two hands. The tool is suspended in a balancer. The balancer is assumed to be correctly adjusted, therefore the pulldown force can be discounted. It is assumed that both male and female operators use the workstation. Therefore two evaluations of external load have been Male operators made, one for male operators and one for female operators. Two-handed operation means there will be no palmar flexion torque. Since the tool is suspended in a balancer, supination and radial flexion torque can be discounted. Real loads can be calculated as follows: Trigger force is measured to 3 N. The trigger can be operated using one or two fingers. On soft joints the installed torque will give a reaction force (pull back) on the operator equal to the installed torque divided by the distance from the spindle to the center of the handle. In this case: 50/0.370 = 135 N. Force/Torque MVC Safety factors Reduced Real load Real / Score N/Nm Speed Frequency Duration MVC N/Nm Reduced Trigger 80 N a1=0.8 a2=0.6 a3=0.8 31 N 3 N 0.1 1 Pull back 400 N 154 N 135 N 0.9 14 Female operators Table 4.18 Evaluation of external load for the Electric Angle Nutrunner Tensor ST61-50-10. Evaluations are given for both male and female operators. Total score: 15 Force/Torque MVC Safety factors Reduced Real load Real / Score N/Nm Speed Frequency Duration MVC N/Nm Reduced Trigger 50 N a1=0.8 a2=0.6 a3=0.8 19 N 3 N 0.2 2 Pull back 300 N 115 N 135 N 1.2 33 Total score: 35 167
168 WEIGHT The electric nutrunner is a typical assembly tool, and it weighs 1.5 kg. Thus, the score is 12. TEMPERATURE A typical tightening cycle lasts 2 seconds. In an 8-hour working day, the average tool running time is normally 2 hours, resulting in a work-cycle time of 8 seconds. The temperature in the handle, measured with the tool running on a soft joint with the maximum torque setting, is 40ºC, thus scoring 13. SHOCK REACTION This electric tool presents two options regarding shock reaction. The joint itself influences the choice. If the joint is a hard joint, the Power Focus can be programmed for a minimum tightening time. This gives a low impulse into the machine, resulting in a very low shock reaction. A medium-soft joint can be tightened in a double sequence, starting with a pre-tightening sequence up to a torque that is lower than the final torque. The pre-torque is calculated to get an acceptable impulse. Final tightening then takes place at low speed, with the speed gradually increasing to pre-set final torque and then gradually decreasing to zero. Final tightening takes longer than 300 ms and is not regarded as a shock. For very soft joints, tightening can be carried out in one sequence, with a smooth ramp up and down. The parameters can be set in a way that achieves the best subjective response from the operator. Different parameter settings for different operators can be stored in Power Focus, and each operator starts the shift by entering a personal code. For a hard joint at a presetting of 50 Nm, the impulse is 4 Ns and the score is 4. VIBRATION The declared vibration value is
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Power Tool Ergonomics E V A L U A T
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Acknowledgements While doing resear
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How to get the best out of this boo
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Work with international standards I
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Good ergonomics is good economics W
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10 SOCIOLOGY INDUSTRIAL SOCIOLOGY S
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12 Work organization No organizatio
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1 outside the production system, an
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1 A seated operator usually has goo
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1 without stretching the trunk. The
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20 The arm sling as a preventive me
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22 Extreme working postures in real
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2 Working with high feed forces req
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2 Working areas of a standing works
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2 body is lifted or tilted, or the
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30 The team is an important factor
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32 Grinders Grinders and sanders ar
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34 HanDle DeSiGn The hand grips on
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36 DUSt anD oil Although the machin
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38 Working environment In general,
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40 SHoCK reaCtion Sudden changes in
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42 practice. Sometimes the chisel h
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44 SHoCK reaCtion These tools do no
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46 heavy, assembly work is often hi
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48 depends on its inertia. The same
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50 bolts. Unfortunately there are a
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52 The low reaction torque in impul
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54 the working environment A typica
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56 Today, the angle nutrunner can b
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58 High torque nutrunners for use w
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60 Wheel nuts on trucks and buses a
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62 Introduction A basic ergonomic p
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64 Handle design The handle of a ha
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66 Arteries Veins (superficial) Vei
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68 Handle size Since a tool handle
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70 However, if the texture is too c
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72 Bibliography Chaffin, D.B. and A
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74 Fig. 3.3 The same feed force app
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76 Pushing and pulling Pushing a to
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78 the object, the shape of the obj
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80 Safety factor a 2 Frequency of t
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82 Comments for different tool type
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84 The trigger is either operated b
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86 used in one handed operations. T
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88 Weight The weight of a hand-held
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90 stability of grip, the center of
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92 Temperature Hand-held power tool
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94 To ensure physical comfort durin
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96 Score 40 30 20 10 0 Bibliography
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98 the dynamic properties of the ma
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100 High motor power and fast clutc
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102 Score 40 30 20 10 0 shock react
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104 piezo-electric crystal. When th
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106 EN 50144 and EN 60745. Both ISO
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108 hole of the wheel are wider tha
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110 In the GTG 40 grinding machine,
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112 RRH machines serves two functio
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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
Page 133 and 134: 132 lubrication. Made from a compos
Page 135 and 136: 134 Grinder GTG 40 F085 The relevan
Page 137 and 138: 136 were simulated by fitting a whe
Page 139 and 140: 138 Drill LBB 26 EPX-060 The releva
Page 141 and 142: 140 applied to the center of the dr
Page 143 and 144: 142 Chipping hammer RRF 31 The rele
Page 145 and 146: 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
Page 165 and 166: 164 operator equal to installed tor
Page 167: 166 Electric angle nutrunner Tensor
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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