PARES - A PROTOTYPING AND REVERSE ENGINEERING SYSTEM FOR MECHANICAL PARTS-ON-DEMAND ON THE NATIONAL NETWORK

We describe a system in which a mechanical designer, working at a CAD station in one geographic location, communicates with a CAM facility i n another geographic location to obtain a fabricated part with rapid t urnaround. Simple mechanical components such as flat plates with holes in them have been designed and manufactured in this way. To rapidly f ixture and measure components, new techniques have been developed that drive a touch trigger probe around the component and its holding clam ps. At present, this implementation is in 2 1/2-D. In the future, comp onents will exhibit greater complexity and include 3-D parts with feat ures on all sides and curved surfaces. The probing techniques will be extended to such 3-D cases and will also allow for measurement of unkn own parts and reverse engineering, e.g., the machining of a repair par t from probe measurements rather than from a CAD Specification. For th is 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 conve rted into the IGES standard format before mailing over Internet. After a CAM facility received them, machine tool commands and setup plans w ere generated. Component fabrication was then demonstrated on a machin e tool, open system, advanced intelligent controller (MOSAIC). This is currently based on a Sun/VMEbus/real-time Unix/C architecture. The va rious phases of this networked CAD/CAM activity were timed and analyze d. Graphical timelines for components reveal which of the individual p hases are the most time consuming and require skilled human interventi on. For example, it is shown that the setup planning for the CNC machi ne tool still requires the experienced judgement of a human machinist with possible inputs from the original designer on such aspects as cri tical tolerances and design subtleties. These findings point out the d irections for future research on concurrent engineering, rapid prototy ping, quality assurance in manufacturing, and reverse engineering tech niques. The research also represents a first step in the direction of a mechanical MOSIS system, for acquiring mechanical components on Inte rnet.