Designing the optimal process target levels for multiple quality characteristics

The selection of the optimal process target has become an important research area in which the focus is to increase productivity and improve product quality. Although the quality engineering literature related to this issue contains a vast collection of work, some questions still remain unanswered. First, most previous studies have viewed this issue from a manufacturer's perspective. When designing the optimal process target in the early stage, the customer's perception of product quality needs to be incorporated. Secondly, many researchers have carried out their studies based on a single quality characteristic. From the customer's viewpoint, however, products are often judged based on more than one characteristic. To address these questions, this paper first studies a multivariate quality loss function to capture customer dissatisfaction with product quality, and then proposes an optimization scheme to determine the most economical process target levels for multiple quality characteristics. The optimization procedures are demonstrated in a numerical example, and the effects of process parameters are examined by conducting a sensitivity analysis.