Scheduling duplicate serial stations in transfer lines

To support the production rate, some transfer line stations with long cycle times must be duplicated. A job is processed in only one of the duplicate stations. If laid out in parallel, this duplication essentially doubles the capacity, but, for practical reasons, these duplicate stations are often laid out in a series. The serial layout has a capacity less than the parallel’s, and also raises some operational questions. The authors enunciated and analysed this actual problem of operating duplicate stations in series. They simulated an existing closed-loop transfer-line with duplicate stations in series using the actual failure and repair characteristics of the automated stations, and compared a new heuristic with three simple policies.