本文以天津市某橡胶公司轮胎产品设计为对象，采用双响应曲面方法对轮胎生产过程中的一个重要质量特征（胶料硬度）进行了优化，并根据双响应曲面方法设计了试验设计软件，试验设计结果找到了达到胶料硬度目标并减少硬度变异的配比条件。

During process design or process optimization, it is quite common for experimenters to find optimum operating conditions for several responses simultaneously. The traditional multiresponse surfaces optimization methods do not consider the uncertain relationship among these responses sufficiently. For this reason, the authors propose an optimization method based on evidential reasoning theory by Dempster and Shafer. By maximizing the basic probability assignment function, which indicates the degree of belief that certain operating condition is the solution of this multiresponse surfaces optimization problem, the desirable operating condition can be found.

Continuous quality improvement is now the focus of research and application in quality engineering. To achieve continuous improvement, it's necessary to integrate quality tools and to plan, design and control the whole process of creating quality. Based on the extensive literature review and the philosophy of concurrent quality engineering, the paper analyzes the relationships among major quality tools such as QFD, FMEA, DOE and SPC and presents a basic model and structure for the integration of quality tools.

This paper addresses a systematic and scientific tolerance design method-six sigma tolerance design. First a specifically quantified goal is determined for tolerance design with an assembly case analysis to show how six sigma is designed into the product. The design and optimized flow is put forward. This method leads to a set of design principles and practices which are embodied in the thinking of concurrent engineering (CE). The philosophy underlying design for manufacturability (DFM) finds expression in CE. Six sigma tolerance design provides a way to achieve six sigma quality and beyond. It is the result of requirements for higher quality product at lower costs.

Process capability analysis is to predict how well the process will hold the tolerance. It is very useful for assisting product developers and process developers in selecting or designing product/process, evaluating and selecting among competing vendors and determining the bottleneck process in terms of process quality. The paper discusses the statistical properties of Cp and Cpk and process capability analysis based on non-normal data and attribute data. A general flowchart for conducting process capability analysis is also given.