Acquiring Manufacturing Processes Knowledge for Design

SUMMARY

Much of the work done in concurrent design assumes that manufacturing process knowledge has been codified and that manufacturing process models exist. However, for new solid free-form manufacturing processes, such as the shape deposition process being developed at Carnegie Mellon, these assumptions are not valid. In the shape deposition fabrication process, a part is built by successively depositing materials in thin layers. Each layer can contain several materials and creating each layer requires several manufacturing subprocesses which include micro-casting, thermal spraying, shot peening and machining. Some of these manufacturing subprocesses are only partially understood; their use in combination to form a single multi-material layer is not well understood; and the process of creating a mechanical part or assembly from thin multi-material layers is also not well understood. One of the salient features of shape deposition, as well as most solid free-form manufacturing processes, is that it requires minimal fixturing and set-up. Once the geometry and materials for a part have been specified, the part can be run through an automated planner and sent directly to the manufacturing cell. Thus, the designer can work more closely with the manufacturing process than is possible in traditional manufacturing systems. This paper describes our work to create a link between design and manufacturing to enable designers to acquire knowledge about the manufacturing process and to develop models of the manufacturing system. Because the shape deposition process is still being developed, design and manufacturing are tightly coupled. We need to design parts to learn the capabilities of the manufacturing process. We need to manufacture parts to refine and adapt the process so that new parts can be designed.