Effects of rejects on in-process inventories in serial production lines

This paper reports the results of a simulation study that determines the effects of rejects on in-process inventory levels. The production line is made up of several stations or stages organised in series, and rejects can occur at any stage along the line. The long-term average reject proportion at each stage is specified, and rejects occur according to the binomial statistical distribution. The results indicate that in-process inventories will be higher in the early stages of the line and will also depend on the average reject proportions at the various stages. The results of the paper will help management determine just where on the production line its quality management efforts should be directed to reduce in-process inventories and hence improve efficiency.