Abstract
Following the growing public interest of product recalls as a social issue, improving the product quality is becoming a very important concern for industries. We have developed and operated a design defect prevention system based on SSM (Stress-Strength-Model), which is a method to structuralize design knowledge using a chain of causes and their effects. How to let busy designers build and utilize structured knowledge is a very important issue in operating a structured knowledge system. This paper describes know-how to solve the above concern in developing and operating the design defect prevention systems which builds and utilizes SSM design knowledge. Our know-how consists of an organizational structure to enable busy designers to build structured knowledge. Rules for building SSM knowledge to be able to generate practical design checklists and a procedure for predicting the effect and cause of the failure in a real design site. The design defect prevention system has been operated since 2006 for controlling circuit design and structural design in developing air-conditioning equipment. The system achieved a 59 percent reduction of the number of design changes noticed and additional 12 percent of check items which manpower design review could not point out. Furthermore, we confirmed the improvement of the design ability to prevent design defect through a competence-based questionnaire for ten designers.
