An Investigation of Order Review/Release Policies and Dispatching Rules for Assembly Job Shops with Multi Objective Criteria

This work deals with the significant aspects of a simulation based experimental study of two shop floor control polices: order review/release (ORR) and dispatching rules for scheduling an assembly job shop in which multi-objective criteria is considered. A simulation of model of an assembly job shop which consists of one assembly work station with two machines and seven machining work stations with two machines in each work station is developed. Six dispatching rules and four ORR mechanisms identified from the literature are incorporated in the simulation model. Grey relational analysis is used for ranking the dispatching rule-ORR combinations. The performance measures considered in this study are mean flow time, mean tardiness and machine utilization. Simulation experiments have been conducted in an environment with products consisting of single level assembly structure, two level assembly structure and three level assembly job structures. The results indicate that Job Due Date rule with Interval Release policy performs better in comparison with the other dispatching rule- ORR combinations investigated in this study.