RELEASE POLICIES FOR ASSEMBLY SYSTEMS

We consider a production system consisting of several fabrication line s feeding an assembly machine. The machines in the fabrication lines a nd at assembly are assumed to have general processing time distributio ns. Releases to the system are governed by the kanban release mechanis m. We first derive a heuristic for the throughput of this system by re placing the assembly system under kanban release by an equivalent syst em under CONWIP release and by making use of an approximation for the throughput of a CONWIP assembly system (Duenyas, 1992). Comparisons wi th simulation show that this heuristic is robust over a wide range of conditions. We also address the issue of which release mechanism is mo re effective in obtaining a desired throughput level. with the minimum possible work-in-process inventory level in the system. We present bo th analytical and simulation results to demonstrate that the CONWIP re lease policy seems to be a more effective release policy for assembly systems.