Essays on scheduling with controllable processing times in flexible manufacturing systems

In this study, we consider FMS loading, scheduling and tool management problems simultaneously. Our aim is to determine the machining conditions, to load and schedule parts on the nonidentical parallel CNC machines and to determine tool allocation and replacement decisions. We consider due date and cost based objectives. The due date related objectives are minimization of weighted tardiness, and weighted earliness/tardiness. The cost related objective is the minimization of the manufacturing cost, which is the sum of machining, tooling and nonmachining costs. An important issue in flexible manufacturing systems is that the processing times can be controlled by changing the machining conditions. In this study, we consider controllable processing times because of the flexibility they provide for finding alternative solutions in predictive and reactive scheduling.