Geometry-based machining precedence reasoning for feature-based process planning

Abstract

This paper presents a method to generate machining precedence relations systematically based on the geometric information of the part. The feature recognition method using Alternating Sum of Volumes with Partitioning (ASVP) Decomposition is applied to obtain a Form Feature Decomposition (FFD) of a part model. Form features are classified into a taxonomy of atomic machining features to which machining process information has been associated. Geometry-based precedence relations between features are systematically generated using the face dependency information obtained by ASVP Decomposition and the features' associated machining process information. Multiple sets of precedence relations are generated as alternative precedence trees based on the feature types and machining process considerations. These precedence trees can be further enhanced with precedence relations from tolerance specifications and machining expertise. Machining sequence planning can be performed for each of these precedence trees while minimizing the number of tool changes. The precedence trees may then be evaluated based on machining cost and other criteria. The precedence-reasoning module is currently being implemented within a comprehensive computer-aided process planning system.