WORK SCHEDULING IN FMS UNDER TOOL AVAILABILITY CONSTRAINTS

Various planning problems in FMS are introduced and the impact of tooling considerations observed. The effect of tool variety, product variety and product similarity on the frequency of two types of tool change, due to product variety and due to tool wear, are identified. The problem area is illustrated with reference to an example FMS, for which it is shown that tool capacity constrains scheduling decisions. The possibility of developing some part launch sequence which would minimize the need for tool changes is considered but found ineffective. Dynamically selecting jobs from queues so as to minimize tool change is also found ineffective. A linear programming mode, due to Menon and O'Gradey (1984), is described, but found to require further evaluation. A tooling post-processor for a simulation model is presented which computes the number of tool changes in any work schedule.