Layered Drum-Buffer-Rope-Based Scheduling of Reentrant Manufacturing Systems

Reentrant flow is a phenomenon in which a product revisits several machines multiple times on its production route. A manufacturing system with reentrant flow is well recognized as a highly complex system. Its reentrance feature challenges the scheduling researchers. To cope with this problem, a kind of drum-buffer-rope (DBR) technique proves to be a viable robust method for complex manufacturing system scheduling. This paper investigates DBR-based scheduling for reentrant manufacturing with a novel strategy. First, the multiple reentrant production flow is transferred into nonreentrant layer production lines. Then, the DBR-based scheduling algorithm is studied, and a layered scheduling algorithm (LSA) and the extended LSA are proposed. The proposed layered DBR-based scheduling strategy and the algorithms are demonstrated via a case study. They significantly outperform some commonly used policies in terms of such performance measures as mean cycle time, work-in-process, and equipment utilization ratios.