An Economic Evaluation of Job Shop Dispatching Rules

Abstract

This paper attempts to provide an economic framework in which various job shop dispatching rules can be evaluated. It shows the relative advantage of shortest processing time rules in gaining increased utilization of the shop facilities and the relative advantage of minimum slack rules in meeting promise commitments. The paper graphs each of four kinds of costs (costs of long promises, costs of missed promises, costs of idle resources, and costs of carrying inventory) against two independent variables, the amount of work-in-process inventory and the tightness of the promises. It demonstrates the kind of cost structure which causes a minimum slack rule to be superior to a shortest processing time rule.