Operation sequencing in a FMS

SUMMARY In simulation studies of an FMS serious congestion problems were observed. Since they had not occurred in earlier FM systems built by the same manufacturer comprising similar machines and control software, it was concluded that they must be caused by the nature of the operation sequences and times of the parts to be produced. This paper reports the results of experiments to assess the dependence of the system's performance on the sequence in which jobs are launched, the relative times of successive operations, machine groupings and product mix. The principal performance measures were the production achieved within a certain time period and the ratio for each part of its processing time to its time in the system. The results are presented, and, contrary to expectation, in most cases there were no statistically significant effects. The possible reasons for and implications of the results are discussed.