A graph-matrix approach to setup planning in computer-aided process planning (CAPP)

An innovative approach was developed to solve the problem of setup planning, which is the most critical problem in process planning for discrete metal parts. Setup planning is the act of preparing detailed work instructions for setting up a part. It is the first and the most important step in process planning. The purpose of setting up a part is to ensure its stability during machining and, more importantly, the precision of the machining processes. Therefore, tolerance control can be achieved proactively via setup planning. This fact has been somewhat overlooked in the computer-aided process planning (CAPP) research community. While many researchers focused their attention on tolerance chart analysis, the issue of tolerance analysis for setup planning was relatively unexplored.

The major objective of this research is to improve the performance of CAPP systems by developing a systematic approach to generate practical setup plans based on tolerance analysis. A comprehensive literature review on tolerance control in CAPP was conducted. It was found that tolerance chart analysis, a traditional tolerance control technique, is reactive in nature and can be greatly improved by solving the problem of setup planning. In order to develop a theoretically sound foundation for tolerance analysis-based setup planning, the problem of tolerance stackup in NC machining was analyzed in terms of manufacturing error analysis. Guidelines for setup planning were then developed based on the analysis. To systematically solve the setup planning problem, a graph theoretical approach is proposed. The design specification of a part is represented as a graph. The problem of identifying the optimal setup plan is transformed into a graph search problem. A setup planning algorithm for rotational parts was then developed and its efficiency and effectiveness evaluated. The result is promising. The same principle was then applied to prismatic parts and resulted in a setup planning algorithm for prismatic parts. The algorithms were then computerized. A setup planning program was developed under the Microsoft Windows environment using C++.