Scheduling manufacturing systems with work-in-process inventory control: multiple-part-type systems

We have studied here the real-time production scheduling problem for multiple-part-type flow shops. The system under consideration consists of many machines and produces many product types. Each part goes through the system following a pre-defined routeing and may visit each machine at most once. We consider three classes of activities: operations, failures or repairs and starvation or blockage. The scheduling objectives are to keep the actual production close to the demand and to reduce the work-in-process inventory and cycle time. A three-level hierarchical production control model is developed to regulate production for the manufacturing systems. The control policy specifies how to react to machine failures. It also tells how to allocate limited system capacity among all the part types. It utilizes the material and the space in the storage buffers to alleviate the propagation of a failure to other machines in the system.