Sequencing rules, progress milestones and product structure in a multistage job shop

This research examines the performance of fourteen due date oriented sequencing rules in a simulated ten machine multistage job shop having one assembly work centre. Each sequencing rule is tested using three methods of setting due date milestones to control the progression of a job toward completion. These methods are: (1) job due dates, (2) assembly due dates, and (3) operation due dates. Both the sequencing rules and progress milestones are evaluated with respect to the complexity of the product’s structure. The findings indicate that the practice of using component due dates to sequence jobs as done in many MRP environments may not be appropriate. In fact, the use of progress milestones worsened the performance of the fourteen dispatching rules for all performance criteria collected. Three of the fourteen dispatching rules tested were found to result in consistently poorer performance than the remaining eleven rules. Very little difference was found between the performance of these other eleven dispatching rules. Also, the sequencing rules were found to perform equally well in a shop characterized by tall BOMs as in a shop characterized by flat BOMs.