| Tolerance synthesis is a major task of product and process design and is in a period of extensive study due both to increased demands for quality products and to increasing automation of machining and assembly. Optimum tolerance design and synthesis ensures high quality products at low cost.;In practice, design and manufacturing tolerances are usually specified and tolerance analysis and synthesis for these two kinds of tolerances are required. The tolerance design tasks are traditionally performed separately by the designer and the process engineer. Unfortunately, in such separate efforts, designers generating the product design are often not aware of the constraints and limited resources, such as available machining machine tools and their capabilities. This may be due to either lack of communications between the designer and the process engineer, or the designer's lack of knowledge of the manufacturing processes. Such a design often results in a process plan that cannot be effectively executed or that can only be executed at unnecessarily high cost. Therefore, in order to enhance product manufacturability, quality and cost effectiveness, design and manufacturing tolerance design should be optimized concurrently.;The research presented in this dissertation has dual central themes: (1) formulation of analytical models for integrated design/manufacturing tolerance analysis and synthesis, and (2) development of a solution procedure for the optimization models of tolerance synthesis.;The integrated design/manufacturing tolerance analysis provides a prediction of product quality level based on the given manufacturing conditions and a quantitative measure for identifying the most critical process(es) to improve for achieving a higher product quality level. The results from the tolerance synthesis can be used as a guideline for selecting equipment and determining the level of process control for component fabrication. The tolerance allocation can be performed based on two criteria: least manufacturing cost and the maximum robustness of tolerance allocation.;In summary, the research ties together dissociated efforts that tend to treat design tolerancing and manufacturing tolerancing as separate problems. The goal is to achieve the most economical and robust manufacturing through tolerance optimization. This is the vision underlying this research. |
