Scheduling optimization of a real flexible job shop including side constraints regarding maintenance, fixtures, and night shifts

We present a generic iterative procedure for the scheduling of a real flexible job shop, the so-called multitask cell at GKN Aerospace Engine Systems in Sweden. A time-indexed formulation of the scheduling problem is presented—including side constraints regarding preventive maintenance, fixture availability, and unmanned night shifts. This paper continues the work in ”Scheduling optimization of a real flexible job shop including fixture availability and preventive maintenance” [Thörnblad et al., European Journal of Industrial Engineering, 2015], with an improvement of the iterative solution procedure, and the inclusion of constraints regarding night shifts during which only unmanned processing is allowed to be scheduled. Schedules resulting from our procedure and from the use of two priority dispatching rules are compared. The gain of including the night shifts constraints is significant. Despite the added complexity, our methodology produces near-optimal schedules for industrial data instances for the coming shift within an acceptable practical time frame