Abstract
As an order release system for multi-stage production inventory systems, the Kanban system has been developed, and its alternative, the concurrent ordering system was also proposed. In the Kanban system, an order is released not immediately after a demand arrives, but after the production or transportation for the demand is available. On the other hand, in the concurrent ordering system, it is released immediately after a demand arrives. The order release process in the Kanban system leads to the delay between the two points in time as compared with that in the concurrent ordering system. The delay has advantages and disadvantages. Therefore, it is necessary to select an appropriate order release system responding to the conditions and to switch systems as the conditions change. Previously, reactive JIT systems, in which the buffer inventory level is controlled responding to unstable changes in demand, were proposed. In addition to these systems, in this paper, switching between the Kanban and concurrent ordering systems is proposed. In the proposed system, the time series data of demand is monitored, and switching the order release systems and controlling the buffer inventory level are considered when an unstable change in demand is detected with exponentially smoothed moving average charts. The effectiveness of the proposed system is clarified by simulation experiments. As a result of simulation experiments, it is clarified that the proposed system can react to unstable changes in demand by satisfying the required level for the mean waiting time of product demand. Also, for satisfying the required level, it is necessary that the proposed system possesses much less work-in-process inventories than previous systems which control only the buffer inventory level and do not switch order release systems.
