Scheduling with setups on a two-machine FMS

The types of automated operations a flexible manufacturing machine can perform depend on the tools available in its tool magazine. Since magazine setups are usually non-automated, the time and effort cost for such setups is not negligible for scheduling purposes. This paper considers the scheduling problem of minimizing the completion time of a joblist, where each job requires two operations with the same precedence order, on two machines each capable of performing both operation types but requiring a magazine setup if one operation type is to be followed by the other. The paper shows that in an optimal schedule, at most one setup is required on each of the two machines. Heuristics are developed for scheduling a joblist on this two-machine flexible manufacturing system (FMS). For an empirical evaluation, randomly generated joblists are scheduled using these heuristics. As would be expected, schedules with zero setups are better when the setup time is large; for small setup times schedules with one and two setups become competitive.