An optimization approach to the integration of computer-aided fixture design with macro process planning for three-dimensional prismatic workpieces manufactured on CNC machining centers

OFDS (Optimized Fixture Design System) is a computerized fixture design system which employs both an optimization method and fixture design rules to automatically design a progressive fixture for prismatic workpieces manufactured on CNC machining centers.; A linear integer programming model together with fixture design rules are developed to integrate fixture design with macro process planning. The MPSX (Mathematical Programming System Extended/370) is used to solve for an optimal solution. The optimal design is dependent upon part specifications and the user's design strategy. The user can emphasize the following four different design weights namely, a stability value, a machining sequence, a previously machined area use, and the number of fixtures. A number of fixture set ups, an orientation of the workpiece in each set up, and a support pattern are obtained as a result of the optimal solution. Given this information, a bill of materials of all fixture components (i.e., supports, locators, and clamps) is then generated. OFDS is tested on several manufactured workpieces. The results are compared with existing fixtures and scrutinized by tool design experts. It can be concluded that the design layouts are acceptable and practically sound.; With the advent of OFDS, the computerized fixture design system is a more systematic and numerical approach. The progressive fixture for the whole workpiece is simultaneously designed and an integration of fixture design with process plan is successfully accomplished.