During the process of concurrent design, a designer must focus on meeting the changing requirements of customers and reacting to the rapid decrease of the life-cycle of the product in a dynamic market. However, the cost induced by the quality delinquent and aftermarket service is a critical factor in the enterprise profit. This research proposes a product design methodology that integrates the grey relation approach to quality function deployment (QFD) and quality engineering (QE) to solve the problem. It is noted that the process increases customer satisfaction and enhances product quality in response to global competition. Based on the results of systematic market research performed on customer requirements (CRs), the hierarchical clustering technique and grey theory have been applied to identify, categorize, and evaluate CRs to rank their grey relational importance. The critical design characteristics (DCs) have been identified using QFD, which applies the semantic differential method on the relationship matrix cell to evaluate their relationship with CRs. The selected DCs are then evaluated to determine noise and possible loss of quality using the orthogonal experiment of the Taguchi method. The objective of the optimization process is to integrate QFD and QE into the development process and to optimize the quality of product development. With support from a timer manufacturer, six existing products have been selected to demonstrate the applicability of the approach described above. This robust product design process provides encouraging evidence for a new approach that can improve quality, reduce variation, and increase customer satisfaction and enterprise profit.
