Processing in a multi-machine batch manufacturing system with sequence dependent cost

Many workcells in batch manufacturing systems are populated with multiple, nonidentical machines that perform similar tasks. Because of the size of a batch when a job arrives, it may be uneconomical to set up two or more machines to process the same job simultaneously. An economic decision has to be made as regards which machine in the cell to assign the job. Likewise, many multi-operation jobs can be processed using one of several feasible operation sequences that may lead to different total manufacturing costs. The cost differences are the result of several factors, among which are processing time and cost dependencies between operations, fixturing require- ments, and material handling requirements. When the workcell machine selection decision is considered along with the oper- ation sequencing decision, determination of the best machine in a cell and the best operation sequence for the batch is a non- trivial task. In this paper, we address the problem of selecting the best machine within a cell and the best operation sequence for a batch when operation cost is machine and sequence depen- dent. The problem is modeled mathematically and solved using a heuristic algorithm. The performance of the algorithm is com-pared with that of an exact solution procedure.