In this paper we analyze continuous- ow production lines consisting of a number of machines or servers in series and a finite buffer between each pair of machines. Each machine suffers from breakdowns, for instance because of failures, cleaning, changeover, etcetera. The resulting up- and downtime periods are generally distributed. Because of breakdowns and non-identical machine speeds, the machines are in uenced by each other, resulting in starvation, blocking, and speed adaption. We are interested in throughput and mean buffer content of this production line. The newly developed method relies on decomposition of the production line into two-stage, one-buffer subsystems. The parameters for each subsystem are determined iteratively. A crucial feature of the model is that we deal with generally distributed up- and downtimes. The use of aggregation techniques on the subsystem level is important to be able to analyze larger production lines of up to 16 machines. The proposed method performs very well on a large test set consisting of over 49,000 cases. Remarkably, the performance of the method does not deteriorate for cases with high variation in up-and downtimes, making this model suitable for highly unpredictable up- and downtimes as often seen in practice.
|Titel||Proceedings of the 8th International Conference on Stochastic Models of Manufacturing and Service Operations (SMMSO 2011, Kusadasi, Turkey, May 28-June 2, 2011)|
|Status||Gepubliceerd - 2011|