Robustness analysis of Demand Driven Material Requirements Planning flowshops in the presence of rush orders

The execution phase has received limited attention in the Demand Driven Material Requirements Planning (DDMRP) literature. In particular, the presence of rush orders in DDMRP systems is an unaddressed issue that is a common barrier to the application of the method. This paper aims to establish flowshops able to handle rush orders in a DDMRP system while maintaining high service levels for non-rush orders. Using Discrete Event Simulation, we designed a non-preemptive DDMRP flowshop to evaluate how rush orders affect service levels under different scenarios of rush order ratios, lead time settings, and prioritization policies. The results show that the DDMRP flowshop remains robust when rush orders account for 20% of capacity and that limiting prioritization in the production line ensures effective rush order management without compromising performance. These findings provide practitioners with insights into how to effectively maintain the robustness of DDMRP systems when reconciling rush and non-rush orders.