A HIERARCHICAL APPROACH FOR METAL PARTS FABRICATION

When planning the design and operation of a manufacturing system in wh ich numerically controlled (NC) machine tools are used to produce a va riety of parts, a number of important factors must be taken into consi deration. This paper addresses certain of these design and operational planning problems and develops a supporting optimization framework. A methodology is proposed for machining batches of parts on groups of m achines in a way that accounts for machine loads and tool assignments. The models we develop consider the effects of variability and correla tion of the demands among the parts. This is done so that the manufact uring system could accommodate wide fluctuations in demand without the machines suffering from significant over- and under-capacity utilizat ion during the system's dynamic operation. The proposed approach is an integrative one, which recognizes the decisions that have to be made, the sequence in which they must be made, the computational complexity of the problem, and various operational constraints.