A production planning framework for flexible manufacturing systems

The authors present a hierarchical production planning framework for modeling flexible manufacturing systems. Based upon an empirical investigation of 155 flexible manufacturing systems in operation worldwide, this framework consists of three linked levels: determining the quantities of products to be made in any given period, grouping the products to increase machine utilization, and sequencing each of the discrete units in real time. Mathematical programming models are used to describe the decision problems qualitatively at each level in the hierarchy. The purpose of the formulations is to illustrate the approach and the tradeoffs and not to provide a definitive solution. In considering robustness and optimality, the authors show that currently available scheduling theory and algorithms are quite sufficient to provide both. Finally, they describe an application of the framework to a very successful generation of turnkey systems from Hitachi-Seiki.