Appreciation of the zone of convenient reach by naive operators performing an assembly task

Abstract Little research has been done relating the layout of an assembly workplace in terms of the ‘zone of convenient reach’ (ZCR) to occupational health risks to the operators. Four groups of ten subjects were asked to assemble hacksaws under four experimental conditions. In three conditions subjects were free to arrange their own workplace, with each condition representing an improvement in terms of using a jig for assembly and being given instructions on proper use of the jig. The fourth condition used an ergonomically designed workplace where all parts were kept within the ZCR. Subjects had no practical experience in assembly work and were from non-engineering backgrounds. A video recording system was used to record the performance times, hand movements, body posture and strategies in assembling the hacksaw. Results showed significant learning between the first trial and the rest of the 20 trials for all the experimental conditions. The results also showed that an improved layout of the workplace would potentially produce the following benefits: (i) Reduced occupational health risks to the operator from back injury problems through safer use of hand movements and body posture. (ii) Increased productivity for the employer through more economical use of hand movements. Relevance to industry An improved workplace design, achieved through use of an assembly jig, instructions on proper use of the jig and layout of components within the zone of convenient reach, can reduce work times and also reduce occupational health risks. Occupational health risks may be reduced by the operator having less contralateral movements and less use of two hands to pick single parts. Time is reduced through use of more simultaneous motions.