Period batch control in group technology

Group technology (GT) offers many advantages to firms engaged in batch manufacturing, including lower setup times, reduced lot sizes, lower lead times, and easier production planning and control. Period Batch Control (PBC) has been proposed in the literature as a simple production planning and control system for a GT environment, based on the choice of a cycle length. Unfortunately, there are no published studies providing guidelines for the choice of an optimal cycle length. In this paper the authors develop a cost minimization model for examining the choice of cycle length, and demonstrate its use by applying it to four published data sets. The analysis shows that the cell design itself directly affects total inventory and overtime costs and the choice of cycle length; that demand increases can be very expensive for a given cell design; and that the degree of demand uncertainty is an important factor in PBC design. The key managerial consideration is the amount of slack capacity to build into the cell designs to handle demand uncertainty. Finally, the authors studied the effect of safety stocks on costs and cycle lengths. Results indicate that safety stocks can reduce both total cost and cycle length.