The use of value-based priorities when early shipments are forbidden

SUMMARY In this paper we examine the direct use of cost/profit information in random and flow shops where early shipments are forbidden. The ‘forbidden early shipment’ environment is typical of many JIT situations, since vendors must deliver parts on their due dates, not before. Hence an order finishing early must be held in a finished-goods inventory until its shipment date. Therefore managerial policies are needed which finish jobs right on time, neither early nor late. This paper looks at value-based and time-based priority scheduling rules and examines the performance of these rules in money terms, as well as by earliness and tardiness measures. Overall, the results show that forbidding early shipments has a major impact on the performance of the value rules proposed in our earlier research.