Quality in product lifecycle is a new focus in quality management, which holds the promise of seamlessly integrating all the quality data produced throughout the life of a product. By analyzing the process of quality management in product lifecycle, the hierarchical relationship among the quality processes, quality objects, quality activities, quality data and quality improvement is clarified. The definition of quality BOM (Bill of Material) is specified in quality domain. The mapping relationship between quality BOM and product BOM is established. Based on quality BOM evolution process, an integrated organization model for quality data is put forward.

Functional modeling is the key step in product design process. To improve the quality of functional modeling, an identification method of key elemental function based on function-failure knowledge was proposed. A function-failure knowledge model for mechanical product was built, which consists of function-failure mode, relationships among failure modes, and failure risk information. By means of the function-failure repository, the approach to calculate risk number (RN) of the elemental function was presented, in which the relationships among failure modes were considered. Then the key elemental functions were identified by the RN value. Finally, a case was studied to illustrate the proposed method.