Throughput of a constant work in process manufacturing line subject to failures

The authors consider a production line consisting of several machines in tandem operating under a constant work in process (CONWIP) control strategy. They assume that processing times are deterministic but machines are subject to exponential failures and repairs. The authors model this system as a closed queueing network and develop an approximate regenerative model (ARM) for estimating throughput and average cycle time as a function of WIP level. They compare ARM with mean value analysis (MVA) and develop readily computable tests of the suitability of the two approaches to a given production system. Through comparison with simulations, the authors show that ARM gives better predictions than MVA in a range of realistic situations.