Transients in flexible manufacturing systems with setups and batch operations: Modeling, analysis, and design

Significant research and practice efforts have been devoted to flexible manufacturing systems. Many of them focus on performance analysis, production and inventory control, planning, and scheduling. Steady state analysis is prevalent in these studies. The transient behavior of flexible lines is less investigated. However, the dynamic changes in customer demands and the uncertain nature in production make the transient performance critical for system control, scheduling, and improvement. Due to non-negligible setups during product change, batch operation is typically carried out in many flexible lines. How to design the system to allocate multiple products, determine batch size, and schedule part sequence is of significant importance to system performance during transients. In this article, an analytical method is developed to evaluate the system throughput, work-in-process, and other performance measures in transient periods for multi-product lines with Bernoulli reliability machines, finite buffers, non-negligible setups, and batch productions. System properties, such as monotonicity, are discussed. Moreover, optimal order assignment and part scheduling in systems with multiple flexible lines are studied. Both centralized and decentralized optimization policies are investigated.