The use of value-based rules to avoid shop disruption

This article models and evaluates the common practice found in many job shops of revising job priorities at the end of accounting periods to achieve specified goals, e.g. monthly dollars shipped. Fourth-week rules are modelled which utilize time priorities the first three weeks and value (cost/profit) priorities the last week for jobs near completion. The performance of these rules is compared to that of rules which use value information throughout the month for both randomly routed and flow routed job shops. These value-based rules are shown to out perform the fourth-week rules at several utilization levels of the shop. In addition, these value-based rules eliminate the shop disruption which often results when fourth week rules are used.