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Six-Sigma provides the opportunity and discipline to eliminate mistakes, improve morale, and save money. Doing things right and keeping them consistent is the idea behind Six-Sigma. A fundamental objective of Six-Sigma is to achieve customer satisfaction with continuous improvement in quality. Process control and manufacturing variation reduction is important but companies often find that the majority of their quality problems were actually created during the design process. An example of improving manufacturing process capability to give bottom line cost savings and customer satisfaction is presented in this paper. The methodology to increase system robustness through Design for Six Sigma (DFSS) is presented and demonstrated through the extension of the case study of crankshaft journal lobing design robustness improvements.

Design for Six Sigma (DFSS) is a systematic process and a disciplined problem prevention approach to achieve business excellence. Robust design is the heart of DFSS. To enable the success of robust parameter design, one should start with good design concept. Axiomatic Design, a fundamental set of principles that determine good design practice, can help to facilitate a project team to accelerate the generation of good design concept. Axiomatic Design holds that uncoupled designs are to be preferred over coupled design. Although uncoupled designs are not always possible, application of axiomatic design principles in DFSS presents an approach to help DFSS team focus on functional requirements to achieve design intents and maximize product reliability. As a result of the application of axiomatic design followed by parameter design, the DFSS team achieved design robustness and reliability. A hydraulic lash adjuster case study will be presented.

“Doing the right things” is important for a company to stay in business while developing the right products to satisfy customers and make profits. Design for Six Sigma (DFSS) is a disciplined problem prevention approach and a systematic process to prevent defects in what is important to the customer. This paper builds on the rationale and opportunities presented in the SAE paper of Six Sigma Disciplines in Automotive Applications for improving design robustness. The methodology to increase system robustness through DFSS is presented and demonstrated through the extension of the case study of crankshaft journal lobing design robustness improvements realized from the traditional DMAIC Six Sigma project presented in the SAE paper of Six Sigma Disciplines in Automotive Applications.

Transfer functions, one of core components in Design for Six Sigma (DFSS), provide the needed relationships between design, process and materials parameters and the CTQs (Critical-to-Quality characteristics) in the product and process development cycle. Transfer function provides direct method for understanding and representing an over all product and process function. Transfer function also provides a strategy for customer voice cascade, function decomposition, physical modeling and concept generation. The concept of transfer function is not new. However, the development of transfer function is not trivial and is a creative and challenging task. In part I of this paper, we will discuss how to develop a transfer function in the DFSS framework. In part II of this paper, we devote our efforts in the discussion of selecting the best transfer function for design evaluation and optimization.