An Effective Method to Reduce Inventory in Job Shops
نویسندگان
چکیده
Inventory plays a major role in deciding the overall manufacturing costs, and a good scheduling system should balance the on-time delivery of products versus low work-in-process (WIP) inventory. In this paper, the “CONstant Work-In-Process” (CONWIP) concept is applied to job shop scheduling to effectively control WIP inventory. A new mathematical formulation of CONWIP-based job shop scheduling with a separable structure is presented. By using a synergistic combination of Lagrangian relaxation, dynamic programming, and heuristic methods, good schedules are obtained in a reasonable amount of computation time. Results show that the new method can directly control the maximum WIP levels while maintaining good on-time delivery performance. Index Terms Manufacturing scheduling, Job shop, Lagrangian relaxation, Work-in-process inventory.
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