Scheduling with Controllable Processing Times

In today's industrial world, demand nature is changing where the customers are looking for a high variety of products. In order to meet varying customer demands, the firms should be flexible enough to produce parts in an efficient way. The flexible manufacturing systems have emerged with the progress in manufacturing technology. A flexible manufacturing system (FMS) is a computer-controlled production system consisting of numerically controlled machines and an automated material handling system. In an earlier study, we showed that the required processing times on a CNC machining center can be determined by adjusting the operational parameters of cutting speed and feed rate for a given performance measure [1]. We know that scheduling decisions are quite sensitive to the processing times, hence we can optimize the scheduling and machining related measures simultaneously by considering the interrelated subproblems of processing time control, cutting tool allocation and machining conditions optimization [2]. For example, advances in cutting tool materials and designs will increase the cutting speeds at which the machining is carried out, consequently reducing machining cost at the expense of higher initial tooling cost and higher nonmachining cost due to more frequent tool changes.