Producibility Models for the Class of Geometric Tolerance Controls
Abstract: This grant provides funding for the development of probabilistic models to perform the mapping of position tolerance constraints and process capability data into a quantitative measure of yield. The class of position tolerance controls addressed by this research represents the dominant class of specification constraints used worldwide in industrial production work spanning mechanical, electronic (printed circuit boards and related assemblies) and other products. A generic 3-dimensional manufacturing error model will be used as input to the formulation of producibility models for the two broad classes of position tolerance control and their variants. Exact or approximate numerical solutions to these models will be developed and an investigation of sensitivity analysis will be performed that will elucidate and quantify the effect of important design and manufacturing error variables on producibility of the class of position tolerance control. A technological implementation of these models will be demonstrated by way of an experimental evaluation of their predictive power.
If successful, the results of this research will lead to models and solution procedures that will provide, for the first time, a quantitative measure of the effect of position tolerance control scheme variables on producibility. The proposed work will also enable a rational comparative evaluation of competing position tolerance control schemes on the basis of producibility. Design engineers with access to basic manufacturing process capability data will be able to assess the producibility of feasible position tolerance control schemes upstream, at the design stage. Manufacturing engineers confronted with the realization of a given position tolerance control scheme will be able to evaluate the minimum accuracy and precision required to meet yield requirements. Demonstration of the technological implementation of these models and solutions in a production setting will provide a rational argument to promote adoption of producibility models as a valuable complementary document to present dimensioning and tolerancing standards.
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