An Effective Method to Reduce Inventory in Job Shops

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 WIP levels while maintaining good ontime delivery performance.

• Type: Conference
• Year: 1999
• Where: ICRA
• Authors: Peter B. Luh, Xiaohui Zhou, Robert N. Tomastik
• Keywords: ICRA 1999, Job Shop Scheduling, Overall Manufacturing Costs, Robotics, WIP Inventory