Form feature and tolerance transfer from a three-dimensional solid model to a setup planning system
Process planning, like most other computer-aided engineering applications, requires the definition of product geometry as input (Shah and Mantyla, 1996). But the geometric information alone is insufficient. Process planning needs additional data on the shapes, such as their dimensions, locations, tolerances, and surface finish. The information should also cover more specialized factors including tool accessibility, fixturing possibihties, and inspectability. Therefore, product data transfer is important and necessary in automated process planning.
However, most CAD systems, even the feature-based design systems which was developed as the need of CAPP, cannot provide exact information, such as dimensions and tolerances, of an object. Until now, most CAD modelers care more about the geometry of a part than other product information, but in fact, the product data, including tolerance information, is absolutely cmcial to CAPP. To realize product data transfer, feature-based design is very instmmental although it has not fulfiUed its promises yet One of objectives in this research is to modify a product data file, which is an exported file of a feature-based CAD system, in order to obtain exact product information which can be used by a CAPP system.