Flow shop scheduling problem with maintenance coordination: A new approach

This study investigates the coordination of production scheduling and maintenance planning in the flow shop scheduling environment. The problem is considered in a bi-objective form, minimizing the makespan as the production scheduling criterion and minimizing the system unavailability as the maintenance planning criterion. The time interval between consecutive maintenance activities as well as the number of maintenance activities on each machine is assumed to be non-fixed. A mixed integer programming formulation of the problem is presented. A special case of the problem, named as single server maintenance is also studied. A bi-objective ant colony system algorithm is presented to solve the problem in focus. Computational experiments are provided in two directions. Firstly, two scenarios are defined for the heuristic information part of the algorithm, using CDS and NEH heuristics. Experiments are provided to select the better scenario. Moreover, a local search is incorporated into the proposed algorithm and two scenarios are defined for this purpose. Some experiments are also provided to select the appropriate local search algorithm.