Comparison of production-line control mechanisms

We study the performance of the kanban, minimal blocking, basestock, CONWIP, and hybrid kanban-CONWIP control policies in a four-machine tandem production line making parts for an automobile assembly line. Cases with both constant and changing demand rates are studied. The main performance measures are the service level and the amount of work-in-progress. We also consider other performance measures such as variability amplification along the line. The results are obtained by extensive simulations. We find that the best parameter choices for the hybrid policy decrease inventories by 10% to 20% over the best kanban policy while maintaining the same service levels. The inventory difference grows as the demands on service level increase. The performance of basestock and CONWIP policies falls between those of the kanban and hybrid policies. The CONWIP and hybrid policies also give significantly better response to changes in the demand rate.