Scheduling batch processing machines in complex job shops

This paper considers a complex job shop problem with reentrant flow and batch processing machines. A modified shifting bottleneck heuristic (MSB) is considered for generating machine schedules to minimize the total weighted tardiness. We observe that the MSB could produce infeasible schedules where cyclic schedules are found. A cycle elimination procedure is proposed to remove the possibility of the MSB generating cyclic schedules in the solution.