Application of simulation for order sequencing in flow-shop production systems

In many cases the functionality and performance of flow-shop production systems depends heavily on the selection of a suitable sequence of orders. The main objectives of order sequencing in production systems are minimization of set-up times, continuous and optimal use of capacities, reliability of delivery, minimization of stock and throughput time as well as avoidance of undue system states. The complexity of the task of order sequencing usually requires the employment of heuristic methods rather than analytical approaches. In this context computer simulation can be used for 1. testing and evaluation of rules for heuristic order sequencing applied to a given production system, 2. iterative optimization of partial order sequences and 3. realization of a closed-loop control system, in which the decision of the next job to be placed is made every time dependent on the actual state of the production system and its change tendencies. Integration of simulation programs within production control stations dealing with order sequencing problems thus allows to increase the performance of the production system as well as to make forecasts of future system states according to a chosen order sequence. In the following article the possibilities and limits of simulation employed to create optimal order sequences for flow-shop production systems will be outlined and discussed and some examples will be given.