On lot streaming in multistage production systems

Recently a model on processing a product in a multistage serial production system by overlapping production between stages is presented in the literature. For minimum in-process inventory the production flow is synchronized by shifting the lot, from a stage to the next in equal shipment sizes. An optimal solution procedure for obtaining the minimum cost of set up, transportation and inventory is also developed taking into account the non-negative set up and transportation times. In their paper, the authors ignored the recently published literature on the topic, where a model is developed to minimize the total cost by synchronizing the production flow in the system by shifting the lot from a stage to the next in equal and unequal shipment sizes, but without considering set up and transportation times. In this note, this model is extended to include the set up and transportation times. Two numerical examples are solved to illustrate the extended model.