A Direct Machining System for Commercial CAD/CAM Packages

Although modern machine tools and controllers have evolved along with the personal computer over the years, the standard input (M&G code files) for CNC machines has not changed. A new method of control called Direct Machining And Control (DMAC) is being developed at Brigham Young University. DMAC is a revolutionary new paradigm for rapid prototyping and CNC control by directly connecting a CAD system with software based DMAC controller. DMAC technology completely eliminates all intermediate files (APT, M&G code, STEP-NC, etc) between the CAD model and the CNC controller by directly processing the geometric tool path entities that are sent from the CAD/CAM system to the motion buffer of the controller. Direct machining maintains the efficiency and accuracy improvements seen in NURBS tool path representation, and also retains associativity between the CAD model and the tool paths driving the CNC machine tool. This paper presents a Direct Machining system designed to directly connect a commercial CAD/CAM systems (Unigraphics, CATIA, CM² and Alias) with a software-based DMAC controller. In this paper, Direct Machining, with its requirements and implications, is explored. The overall DMAC architecture is presented. Parts from the Ford GT car were machined on a Tarus five-axis mill by the DMAC system, and were compared with traditional method which used M&G codes.