Analysis of the effects of group size and learning on manual assembly performance

On the basis of a prior experimental study, this paper performs a further analysis of the effects of group size (one to four workers) and learning (up to four repetitions per group) on manual assembly performance. More specifically, this paper aims to investigate the factors and the extent to which they affect reduced assembly time as a function of repetitions and reduced productivity per worker as a function of increasing group size. The ultimate aim of this study is to increase the understanding of how working in groups of different sizes develops through repetitions when workers are free to organize their work themselves. The results from the video-based analysis show that with a new, relatively complex product, instructions play a crucial role in learning and the losses caused by the inexperience of workers decrease rapidly through repetitions. Unequal temporal workloads between workers in larger groups increase idleness and cause a significant loss of productivity. The findings presented in this paper give insights for industrial managers when assigning workers to products in variable assembly production of highly customized products.