Abstract
Sheet metal forming process may yield unexpected defective products due to many uncontrollable factors such as irregular material properties, lubricants, and variations of other forming conditions. Traditional design methods based on deterministic optimization theory have limited capability of including such factors. In this paper, we propose a method in determining the optimal condition of a sheet metal forming process with conflicting failure modes. A robust design method is used with computer simulations and optimization techniques. A new SN ratio is proposed based on the operating window method, to improve the problems of traditional SN ratio. The robust design process is applied to a sheet metal forming process for an automobile component, and the effectiveness of the proposed method is verified.