Optimal transfer lots for batch manufacturing: A basic case and extensions

Abstract : One of the weaknesses of most MRP systems, is that they do not allow overlapping of activities on a batch by sequential machines. However, by letting the second machine start processing a batch before the first one has finished it yet--a well known idea utilized by many practitioners--we can often achieve considerable improvement in terms of shorter lead time. This requires the use of partial transfer lots. In this paper we address the problem from a theoretical point of view. We optimize the sizes of the transfer lots for overlapping processing on two machines to as to minimize the makespan under a constraint on the number of transfers. We also discuss the issue of several consecutive jobs (batches), and how to extend the solution to several machines in such a manner that all machines process the batch continuously.