Factors affecting performance of period batch control systems in cellular manufacturing

This paper critically evaluates the design and operation of period batch control (PBC), a manufacturing planning and control (MPC) system recommended for cellular manufacturing (CM). A comprehensive conceptual analysis of PBC identifies important system attributes and leads to the proposal and testing of key PBC characteristics. Tests are conducted in a simulated CM flow shop based on an actual operating facility. Results show that maximum cell make-span, the easily observable highest make-span of jobs assigned to any cell for a period, is a key predictor of PBC performance. Results also show that demand variability, extent of unbalanced capacity between cells, and transfer batch size further influence performance. In particular, mean tardiness is found to increase as maximum cell make-span exceeds the period size and as the size of transfer batches increases. Both demand variability and cell capacity imbalance, particularly when the capacity constraint is later in the product flow, further reduce performance. As expected, period size is confirmed as a major determinant of customer service and inventory performance. Reducing period size increases capacity utilization, but reduces inventory and lead time. Finally, because of design similarities, it is shown that a firm currently using materials requirements planning (MRP) in a CM environment can readily convert to the similar, but potentially simpler and easier to use PBC systems. Trade-offs that managers can consider for more effectively using PBC in their own CM shops are also explicitly identified and discussed.