Replenishment planning and control in supply chain management

This research aims to gain insights into the effects of the supply chain factors on performance when using alternative replenishment strategies. The objectives include the development of guidelines to select appropriate strategies and to improve the performance when given a particular strategy. A simulation test bed has been developed to support this research. As well, a methodology based on the statistical analysis of inventory and delivery performance tradeoffs has been developed. This methodology allows main and interaction effects to be evaluated so that material and information flow behaviour can better be understood.; The first experiments compare three replenishment strategies, namely Distribution Requirements Planning (DRP), Reorder Point (ROP), and KANBAN, within distribution channels with no capacity constraints. The supply chain factors studied include: supply chain configuration, demand pattern, lot size, demand uncertainty and transit time uncertainty. A second study extends the research by analyzing the effects of capacity constraints, scrap and assembly processes within a network involving supply, manufacturing and distribution stages. Finally, a study to explore time-phased replenishment strategies (e.g. DRP/MRP) more fully is undertaken. In particular, the effectiveness of safety stock versus safety lead time to protect against variability and uncertainty under capacity constraints is examined.; The results from scenarios without capacity constraints show that DRP is the most robust strategy, followed by ROP and KANBAN. Under seasonal demand, DRP always dominates. KANBAN yields inferior performance, especially under seasonal demand. The relative performances are not generally affected much by capacity constraints, scrap and assembly process. The exception is that under some level demand conditions, KANBAN can provide superior performance due to more consistent material flow to capacity-constrained resources. In time-phased strategies with capacity constraints, high demand uncertainty, seasonal demand, and use of some lot-sizing rules can increase replenishment times and induce supply timing uncertainty. The use of safety lead time is found preferable when supply timing uncertainty dominates demand uncertainty.