COMPLETION TIMES IN MULTIPURPOSE BATCH PLANTS WITH SET-UP, TRANSFER AND CLEANUP TIMES

Once, the number of batches, batch sizes, and production paths have be en determined, and the tasks performed in the units have been sequence d, the determination of completion times is the last step in the sched uling of operations. In this paper, we deal with this problem consider ing that non permutation schedules may occur in multipurpose batch pla nts, once the task sequence in the units and the set-up, load, operati on, unload and clean-up times are given. Finite wait (FW) interstage p olicy is assumed, meaning that intermediates may wait temporarily in d iscontinuous units if the waiting time does not exceed the maximum sta bility time for the intermediate, and assuming that no intermediate st orage is available. A recursive procedure is presented to determine th e start times and the duration of the possible waiting times in the di scontinuous units. Then completion times are calculated adding the sub tasks duration to the start times.