摘要：This paper clarifies the mechanisms and conditions for improving product development performance in overlapping development processes. The (1) product design (upstream) process and (2) mass production preparation (downstream) process are interdependent. Yet, the results of case studies of Company X revealed insufficient robustness against noise that affected product functions in Product A during process (1). In process (2), although overlapping was routinely conducted, subsequent work was subject to continuous redesigning and did not result in a shorter product lead time. In contrast, for Product B, while more man-hours were required, the robustness of preliminary information was obtained by introducing Quality Engineering (QE) in process (1). As a result, by actively utilizing preliminary information prior to production preparation, the mold designer in process (2) is able to perform a “prior examination of the mold,” using methods, such as flow analysis. Moreover, access to the product designer allows the mold designer to pinpoint manufacturability problems/issues and implement the design for manufacturing (DFM) approach prior to production preparation (drawing release). Accordingly, in addition to the exchange of preliminary information, a condition that enables substantial overlapping is the frontloading and commencement of the (2) mass production preparation process at the (1) product design stage. Consequently, meeting this condition enables a considerable reduction in the amount of redesigning required to ensure manufacturability in process (2), a substantial improvement in mass production preparation performance, and a shortening of the overall lead time.
