Scheduling algorithms for flexible manufacturing systems with partially grouped machines

This paper focuses on a scheduling problem in a flexible manufacturing system. Unlike most previous studies, this paper deals with the scheduling problem resulting from a loading plan obtained for the configuration of the partial machine grouping, where machines are tooled differently, but multiple machines can be assigned to each operation. The planned workload of each machine specified by the loading plan may or may not be maintained when scheduling and controlling part flows. In this paper, two solution algorithms in which a given planned workload is maintained are suggested based on decomposition of the entire problem into route selection and job shop scheduling problems. In one algorithm, the two subproblems are solved simultaneously by employing rules for part selection and machine selection, while in the other they are solved using a simulated annealing algorithm and dispatching rules. Performance of the suggested algorithms is tested on randomly generated test problems, and results show that the latter algorithms give better solutions and solve the problems in a reasonable amount of computation time. Also, it is shown from computational experiments that it is better to maintain planned workloads.