Influence of material handling devices on the physical load during the endassembly of cars

The effect of using a mechanical device on physical load was analysed durin g the end assembly of cars. Five tasks, further sub-divided into lifting an d positioning, were performed by someone experienced in working with and wi thout the mechanical tool. A practical methodology was used: the subjective walk and talk through method, the NIOSH equation (1991), a three-dimension al goniometer (Back Tracker) and surface electromyography (EMG) of the rele vant muscle groups. According to the NIOSH equation, 8 out of 10 of the tas ks should only be performed by trained workers and preferably with tools. T he Back Tracker revealed that the mechanical tools reduced posture angles s ignificantly (p less than or equal to 0.05) for installing the windows, but not for left lateroflexion during pre-assembly of windows. It was dear fro m the EMG analysis that using tools did not always decrease muscular activi ty significantly. In general, the appropriateness of each tool needs to be evaluated separately taking the subjective criteria into account. Relevance to industry In this study, the relevance of using a mechanical device to reduce the phy sical load during car assembly, is evaluated. As the tools are expensive, i t is important to the industry whether they are being used and how efficien t they are. (C) 1999 Elsevier Science B.V. All rights reserved.