Assessment of a Complex Machine Mix Problem by Integrated Simulation and Ahp Modeling

The objective of this study is to introduce an integrated simulation AHP model for modeling, assessment and improvement of a machine mix problem with complex queue priorities and service times. Furthermore, there is no closed form expression for such situations, as previous studies show no mathematical models for machine mix with integrated service and queue priorities. The production lines of a powder coating manufacturing system with three parallel machines and queue and service time priorities was considered. The machines produce eight different spray coatings. Production operation starts as soon as an order is received. Spray coatings numbers 1 and 2 are handled by machine 1, spray coatings numbers 3 to 6 are handled by machine 2 and spray coatings numbers 7 and 8 are handled by machine 3. Priority is with the arriving entity (new order) which has identical number as the entity being serviced. Also, if the arriving entity has higher number than entity being serviced and there is no identical order as the entity being serviced in the queue, then the arriving entity occupies the first place in the queue. Service time priority means that a machine is only allowed to service identical products (spray coatings) up to a limited period that is defined as ta. For example, if machine 2 has been servicing product number 6 for the last two hours due to high demand, the remaining allotted time if required would be ta 2. In addition, the services turn over moves clockwise. A new operation is initiated according to queue priority after completion of the operation for product number 6, which would be greater than or equal to ta. The reader should note that closed form expression for such production systems is impossible due to effects of consolidated service time priority and queue priority. The unique feature of this study is integrated simulation AHP modeling of a production system with consolidated service time and queue priorities. The simulation approach of this study for such complex settings may be applied for other similar production systems.