Determining the optimal number of sublots in a single-product, deterministic flow shop with overlapping operations

This paper describes a model for minimizing total costs in a single-product, deterministic flow shop with overlapping operations in terms of the sublot size used. Three types of costs are considered: the inventory holding costs, the transportation costs and the so-called “gap costs” which may result from the intermittent idling of machines between consecutive sublots. We provide explicit expressions for the gaps in terms of the system parameters, and discuss the impact of the transfer batch sizing policy on the average transfer batch lead time and the total gap time in the system. The proposed cost model is believed to be particularly relevant for manufacturing cell environments.