Improving coordination in assembly job shops: redesigning order release and dispatching

Assembly job shops form an important part of make-to-order companies. These high-variety production environments are generally characterized by high shop loads and tight delivery dates. Coordinating the completion times of parts to guarantee a timely start of the assembly operations is complex. Most prior studies on coordination in assembly job shops mainly focus on priority dispatching rules, thereby neglecting the coordinating potential of order release decisions. While release and dispatching methods have been extensively studied in the literature, they lack the refined dynamic mechanisms that are needed to effectively coordinate assembly parts. This study refines order pool sequencing rules for order release by utilizing progress, urgency and load-related status information for coordination purposes. A new selection mechanism focusing on the timely release of critical parts is embedded in the release decision. Furthermore, a newly developed dynamic dispatching rule carefully coordinates parts to be assembled, once they are released to the shop floor. Simulation results show that the newly developed methods for dynamic coordination significantly outperform their static versions.