A simulation study on periodical priority dispatching of WIP for product-mix fabrication

This paper proposes a new dynamic priority dispatching algorithm for the product-mix of work-in-progress (WIP) at a processing station with multiple machines. The algorithm is used to evaluate dispatching priority when each quantum starts. The priority is defined considering both the number of WIP and the decreasing rate of WIP in the incoming buffer. When the priority is high, a single sort of WIP is assigned to a machine for a given period, or quantum. This algorithm, named Pseudo Periodical Priority Dispatching (P3D), P3D was examined through Monte Carlo simulation. In a product-mix, a machine must be adjusted when the WIP is changed. The adjustment frequency and the degradation of the machine utilization due to the adjustment are discussed. The algorithm is able to achieve fair dispatching both at a bottlenecked processing step and a non-bottlenecked processing step.