Polynomial transfer lot sizing techniques for batch processing on consecutive machines

Abstract

Using transfer lots, we can overlap the processing of a batch on several consecutive machines, and thus reduce the makespan considerably. This in turn promotes work-in-process reduction. In this paper we investigate the transfer lots sizing problem for a given batch size under two operating procedures. Our objective is to minimize the makespan subject to a transferring budget. An important part of the solution involves partitioning the problem to subsets of machines without losing optimality. For each part (subset), the first and the last machines operate continuously while intermediate machines may idle intermittently. The first operating procedure we consider calls for the lots to be identical across all machines in each subset. The second operating procedure allows sub-lots for some of the machines or for some of the lots. Through more elaborate, the second operating procedure yields demonstrably superior results. The techniques provide satisfying feasible solutions, which can also serve as efficient bounds for an exact branch and bound inter linear programming model. (KR)