Tooling constraints and shop floor scheduling: A simulation study

Research into the problems of job shop scheduling has dealt with two of three major categories of shop floor resources: machine capacity and labour. Generally ignored has been the impact of tooling constraints, the third form of shop floor resource, on the scheduling process. The impact of tooling is the focus of this study. Using a simple simulation model of a shop operating under varying levels of tooling availability, it is shown that the level of tooling availability has a significant impact on shop floor performance as measured in terms of mean flow time, mean tardiness, number jobs tardy and number of tool changes. Four different tooling assignment rules are evaluated and their effect on system performance is described. The results indicate that tooling assignment rules should consider both job priorities and tooling availability in order to achieve good shop performance. The paper concludes with general recommendations for the management of shop orders facing limited tooling availability.