A generalization of the ‘bowl phenomenon’ in series production systems

Abstract ‘ Bowl phenomenon ’ refers to the increase in production rate obtained by unbalancing a series production system such that the service time increases progressively on either side of the central stage(s). While such a result is valid for production systems with otherwise identical stages, earlier studies have suggested that a different effect may come into play when the stages of the system differ in their variability. In the simplest case of n two-stage system, production rate could be improved by shifting a part of the work load from the more variable stage to the less variable one. From an analysis of three-stage systems with all possible combinations of exponential and deterministic stages, it is shown in the present paper that optimum unbalancing results from a superposition of these two effects. This loads in some cases to a large improvement in the production rate. For the large differences in coefficients of variation considered in this paper, the ‘ variability imbalance ’ clearly plays a ...