Bi objective artificial immune algorithms to the joint production scheduling and maintenance planning

This paper deals with the joint consideration of production scheduling and maintenance planning in manufacturing systems. Most studies on production scheduling deals with this problem by optimizing one criterion related to production but requirements of maintenance aspect are taken as constraints of the problem. This approach is commonly called “scheduling with availability constraints” in the literature [11][12]. In that approach, a few unavailability periods of machines are known and fixed in advance then the production jobs are scheduled according to these periods. However, maintenance and production´s objectives should be considered with the same level of importance. However, performance criteria of production and maintenance are generally antagonist. Hence a solution of the joint production and maintenance problem should be a trade-off between their conflicting objectives. In this paper, a new bi objective methods based on artificial immune system is proposed where production jobs and maintenance activities are flexible and not fixed in advance.