SCHEDULING MANUFACTURING SYSTEMS WITH WORK-IN-PROCESS INVENTORY CONTROL - SINGLE-PART-TYPE SYSTEMS

A real-time algorithm is developed for scheduling single-part-type pro duction lines with work-in-process inventory buffers. We consider thre e classes of activities: operations, failures and repairs, and starvat ion and blockage. The scheduling objectives are to keep the actual pro duction close to the demand, the work-in-process (WIP) inventory level low, and the cycle time short. A three-level hierarchical controller is constructed to regulate the production. At the top level, we determ ine the desirable buffer sizes and the target production level for eac h operation. At the middle level is a production flow rate controller that recalculates the production rates whenever a machine fails or is starved or blocked. The loading times for individual parts are determi ned at the bottom level of the hierarchy. The production scheduling al gorithm is evaluated by using computer simulations for a variety of ca ses. Compared with a transfer line policy, a significant improvement i n system performance is observed.