Integrating CAD and CAM through automated process planning

Abstract

Computer-aided process planning is an important function in the integration of CAD and CAM. There are two approaches in computer-aided process planning— variant and generative. The generative is more suitable to CAD/CAM integration because it can synthesize a process plan. The success of developing a generative process planning system is dependent on the CAD interface and process capability analysis, The direct interface with CAD eliminates the tedious data preparation for a process planning system (i.e., it eliminates coding). The process capability analysis provides an information base for process and sequence selection. This paper presents a generative process planning system—TTPPS (Totally Integrated Process Planning System). TIPPS uses a boundary representation from a CAD database for a part. A user applies the crosshair cursor on a graphics terminal and a menu display to specify surfaces to be machined. The system then utilizes the information stored in a process knowledge base to determine manufacturing processes, sequence, cutting parameters and time estimation. The geometric modelling, process modelling, decision mechanism and a planning example are discussed.