Tolerance Analysis for Validating Manufacturing Process Plans

In manufacturing process planning, it is critical to ensure that the part generated from a process plan complies with tolerances specified by designers to meet engineering constraints. Manufacturing errors are stochastic in nature and are introduced at almost every stage of executing a plan, for example due to inaccuracy of tooling, misalignment of location, distortion of clamping etc. Furthermore, these errors accumulate or ‘stack-up’ as the manufacturing process progresses to inevitably produce a part that varies from the designed model. The resultant variation should be within prescribed design tolerances. In this work, we present a novel approach for validating process plans using 3D tolerance stack-up analysis by representing variations of nominal features in terms of extents of their degrees of freedom within design and manufacturing tolerance zones. We will show how the manufacturing error stack-up can be effectively represented by composition and intersection of these transformations. We demonstrate several examples with different tolerance specifications to show the applicability of our approach for process planning.