PARES: A prototyping and reverse engineering system for mechanical parts-on-demand on the national network

Abstract We describe a system in which a mechanical designer, working at a CAD station in one geographic location, communicates with a CAM facility in another geographic location to obtain a fabricated part with rapid turnaround. Simple mechanical components such as flat plates with holes in them have been designed and manufactured in this way. To rapidly fixture and measure components, new techniques have been developed that drive a touch trigger probe around the component and its holding clamps. At present, this implementation is in 2 1 2 - D . In the future, components will exhibit greater complexity and include 3-D parts with features on all sides and curved surfaces. The probing techniques will be extended to such 3-D cases and will also allow for measurement of unknown parts and reverse engineerin, e.g., the machining of a repair part from probe measurements rather than from a CAD specification. For this reason, we call our system PARES, which stands for prototyping and reverse engineering system. In our initial experiment, components were designed using commercial CAD systems. Completed CAD files were converted into the IGES standard format before mailing over Internet. After a CAM facility received them, machine tool commands and setup plans were generated. Component fabrication was then demonstrated on a machine tool, open system, advanced intelligent controller (MOSAIC). This is currently based on a Sun/VMEbus/real-time Unix/C architecture. The various phases of this networked CAD/CAM activity were timed and analyzed. Graphical timelines for components reveal which of the individual phases are the most time consuming and require skilled human intervention. For example, it is shown that the setup planning for the CNC machine tool still requires the experienced judgement of a human machinist with possible inputs from the original designer on such aspects as critical tolerances and design subtleties. These findings point out the directions for future research on current engineering, rapid prototyping, quality assurance in manufacturing, and reverse engineering techniques. The research also represents a first step in the direction of a mechanical MOSIS system, for acquiring mechanical components on Internet.