Each discipline optimizes its task to the best of its ability. Each manufacturing discipline has its own objectives and criteria of optimization according to its function. For example: the designer main objective is meeting product specifications: the process planner?s main objective is that the items will meet drawing specifications: the production planner?s main objectives are meeting the due date, and minimizing work-in-process. The profit objective is not on top of the list of any manufacturing discipline. Even if each discipline functions optimally, this does not necessarily guarantee overall optimum success with respect to management?s prime objectives. The traditional manufacturing cycle is a one-way chain of activities, where each link has a specific task to perform and the previous link is regarded as a constraint. Thus, for example, master production schedules accept the routing and bill of material as fixed (as well as quantities and delivery dates): it does not question these data and its planning must comply with them. Process planners accept the product design without question: in fact, they do not even consider the product as a whole, but rather, the processing of each item is regarded as a separate task. The capacity planner accepts the routing as given, and employs sophisticated algorithms to arrive at an optimum capacity plan.