There is an emerging consensus that existing layout configurations do not meet the needs of the multi-product enterprise and that there is a need for a new generation of factory layouts that are more flexible, modular, and more easily reconfigurable. In this article, we offer a review of state of the art in the area of design of factory layouts for dynamic environments. We report on emerging efforts in both academia and industry in developing alternative layout configurations, new performance metrics, and solution methods for designing the "next generation" of factory layouts. In particular, we focus on describing efforts by the Consortium on Next Generation Factory Layouts (NGFL) to address some of these challenges. The consortium, supported by the National Science Foundation, involves multiple universities and several manufacturing companies. The goal of the consortium is to explore alternative layout configurations and alternative performance metrics for designing flexible and reconfigurable factories.1

A tolerance chart is a graphical representation of a process plan and a manual procedure for controlling tolerance stackup when the machining of a component involves interdependent tolerance chains. This heuristic, experience-based method of allocating tolerances to individual cuts of a process plan can be embodied in a computer-based module. This paper introduces a graph theoretic representation for the tolerance chart. A special path tracing algorithm is used to identify tolerance chains from this graph. Optimal tolerance allocation among individual cuts is achieved using a linear goal programming model instead of existing heuristic methods. A 1D0re comprehensive mixed integer programming model is developed to incorporate' linear tolerance cost functions and alternative process selection.

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