Scheduling with forbidden early shipments: Alternative performance criteria and conditions

This paper attempts to integrate some of the recent research on several different aspects of scheduling production systems where early shipments are forbidden. In particular, this paper focuses on scheduling-rule development, order-release policies, due-date-setting policies, and the use of overtime on a selective basis. In addition, multiple performance criteria, ranging from net present value to average tardiness, are included. The various policies are examined using a simulation model of a hypothetical job shop and statistical significance is reported. The ‘best’ policies are given and shown to be dependent on the environmental conditions being modelled, such as utilization and tightness of due dates. The findings on overtime are that the net present value measure is not affected, but time-based measures are improved. In addition, delayed release is shown to be beneficial whenever job earliness is penalized.