Computer-aided design for rapid tooling: Methods for mold design and design-for-manufacture

Physical models and prototypes are fundamental to superior product development and production. Rapid Tooling techniques have the potential to dramatically reduce the time and cost in producing limited quantities of functional prototypes in final material. However, the current usage of Rapid Tooling has two problems: (1) mold design for parts with a wide variety of geometries may take a long time; (2) design iterations between designers and manufacturers may take a long time before different design requirements are achieved in the prototypes. They overshadow the time and cost benefits of Rapid Tooling. In this dissertation, these two problems are addressed by developing a Mold Design Method and a Design-for-Manufacturing Method respectively.; Based on Computation Geometry, a Multi-piece Mold Design Method is developed to automate several important mold design steps, including determining parting directions, parting lines, and parting surfaces, and constructing mold pieces for multi-piece molds. The method is employed to develop a Rapid Tooling Mold Design System, which has been used to design molds to fabricate prototype parts with widely varying complexities. Two test parts and five industrial parts are presented in the dissertation to illustrate the usage of the mold design system. The running time of the system is tested for each part. The mold design results are also verified by physical experiments.; Based on Decision-Based Design, a Design for Rapid Tooling System is developed to aid manufacturers to tailor a submitted part efficiently and effectively. A basic idea of this work is that for Rapid Tooling the burden of design-for-manufacture can be transferred to the manufacturer by geometric tailoring decision templates. Three testing examples illustrate that the design freedom given by the designer to the manufacturer is important for reducing the iterations between the designer and manufacturer. By synthesizing decisions of part design, rapid prototyping process, and injection molding process variables, a solution strategy and a three-stage solution process are proposed for the system. Two case studies, a robot arm and a camera roller, are used to test the system. Physical prototypes of the tailored part designs are produced for the validation of the DFM method.