The impact of priority rule combinations on lateness and tardiness

Several recent studies have explored the concurrent deployment of different priority rules at different processing stages of a manufacturing system. This study investigates the same issue by combining three popular simple priority rules with a combinatorial rule. In a three-stage flow shop, these rules are combined into 64 combination schemes and their performance compared under two shop load levels with two due date setting methods. The performance criteria considered are: mean lateness; mean tardiness; maximum tardiness; and per cent of tardy jobs. The results indicate that the rule combinations are a better strategy than their pure forms when various performance measures are jointly evaluated. Particularly, selected combinations of the Modified Shortest Processing Time, Shortest Processing Time, and the Earliest Due Date rules appear to be very effective. While the extent of shop load level shows little impact on the relative performance of the schemes, the endogenous method of due date setting consistently yields better results than the exogenous method.