Ph.D. Thesis Defense by Yong Chen
Friday, July 27, 2001

(Dr. David W. Rosen, advisor)

"Computer-Aided Design for Rapid Tooling: Methods on 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.  Five industrial parts are presented in the dissertation to illustrate the usage of the system.

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 manufacturers by geometric tailoring decision templates.  By synthesizing decisions of part design, rapid prototyping process, and injection molding process, a better decision order of design variables is identified for the geometric tailoring of parts.  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 validation.