2026 Volume 76 Issue 4 Pages 125-137
The diverse needs of customers have led to a demand for production systems capable of handling both make-to-stock (MTS) and make-to-order (MTO) products. A dynamic hybrid MTS/MTO production system addresses this demand. This system includes hybrid machines for MTS and MTO operations, as well as dedicated MTS machines for MTS products. A hybrid machine can produce both MTS and MTO products by adjusting its setup accordingly. By dynamically controlling the setup of each hybrid machine based on current conditions, the system can achieve high utilization with fewer machines. However, frequent switching of machines might occur due to the switching decisions based on only the MTS inventory level and stepwise switching. This study proposes a partial switch-restriction model for hybrid machines in a dynamic hybrid MTS/MTO production system in order to suppress excessive switching. The numerical experiments clarified that the proposed model can suppress the frequency of machine switches, and that the system operating costs can also be reduced when MTS demand arrives more than MTO demand. For the cost minimization problem, a relation was found between the number of hybrid machines and the number of switch-restricted machines so as to obtain a lower cost. Based on this result, a heuristic search method is also proposed in order to quickly achieve effective operation rules. Then, it was shown that the proposed search heuristic could find approximately optimal solutions with less errors at fewer searches by comparing the exhaustive search.
