Modeling of Manufacturing Feature Interactions for Automated Process Planning

This paper analyzes manufacturing feature interactions and presents algorithms for handling feature interactions in manufacturing process planning. A feature precedence network, which specifies the constraints for the machining sequence, and an AND-OR graph, which describes alternative representations, are built. Application of required/optional volumes, the AND-OR graph, and the feature precedence network in manufacturing process sequencing is then explained. Required and optional volumes are defined and their use for analysis of interactions of various machining feature types is explained. Case studies are presented to explain volumetric interactions of holes, slots, and pockets with various dimensions, positions, and orientation in the part geometry. The analysis provides insight into which process-sequencing constraints may be resolved before actual process planning and which have to be postponed to be resolved in final process sequencing. A three-phase algorithm for incorporating of volumetric feature interactions into manufacturing process planning is proposed. The first phase is creation of an AND-OR graph of alternative feature representations. The second phase is building a feature precedence network for a given part as a set of machining sequence constraints. The third phase is analysis of feature interactions for performing geometric updates of machining features during the process sequencing stage.