Comparing Steady-state Performance of Dispatching Rule-pairs in Open Shops

Unlike implemented in other production systems, dispatching in an open shop not only takes into account the job priority at each machine but also the selection of the next machine for any jobs leaving the current machine. The control mechanism for scheduling in an open shop can be utilized by a dispatching rule-pair that consists of a machine-selection rule and a job-dispatching rule. This study conducts a steady-state simulation comparison on the performance of 39 dispatching rule-pairs in open shops. We find that using NINQ as the machine- selection rule can minimize the mean flowtime of jobs while using LINQ as the machine- selection rule can minimize mean tardiness of jobs for most cases. The choice of the best dispatching rule-pair depends on the selected performance criterion as well as the system’s configurations such as utilization factor, number of machines, and processing time distribution of jobs. Finally, under similar system configurations, the best job-dispatching rule in an open shop is different from that of a job shop.