Design for Reliability: Case Studies in Manufacturing Process Synthesis

The task of manufacturing process design is to determine a set of process parameters for a manufacturing task. The design is normally carried out to optimize process performance, such as, to minimize discrepancy from a prescribed shape or to maximize production efficiency. An optimal design, however, is often not the most robust or reliable design because inevitable uncertainties in input variables may cause unacceptable deviations from the optimal point. Robust design is therefore needed to achieve compromise between optimization and robustness. Such a methodology is illustrated in case studies involving process design of laser forming of sheet metal, in which a set of parameters including laser scanning paths, laser power, and scanning speed is determined for a prescribed shape. Response surface methodology is used as an optimization tool. The propagation of error technique is built into the design process as an additional response to be optimized via desirability function and hence make the design robust. The results are also validated experimentally.