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The practices adopted by companies that are succeeding in the quality competition vary, but two common elements can be found. Careful attention to the customer is absolutely paramount. Products must satisfy a diverse customer base, with features accurately targeted to customer requirements. Technology must serve customer needs and wants, or the latest and greatest widget will languish on the shelf. Also, continuous improvement, applied to both products and business processes, is ubiquitous.
At the Eastman Kodak Company, the authors have been participants in the ongoing effort to improve the equipment development process. The result has been a world-class process for developing products. This process features Quality Function Deployment (QFD) for capturing the voice of the customer, Robust Design (Quality Engineering) to deliver the level of quality demanded by the customer, and a disciplined engineering process for managing the business of product commercialization. Much of the Kodak Equipment Commercialization Process is described in Professor Don Clausing's book Total Quality Development (ASME Press, 1994).
Physics and engineering principles are the basis for beginning a good product design or fixing problems with a design that is already in existence. Any graduate from engineering school knows these fundamental subjects as well. They have been used effectively by many generations of engineers. However, they alone are no longer enough. The current competitive situation requires a disciplined engineering process that ties together the multitude of engineering tools currently being taught and practiced.
The need to further define the process for linking the principles of engineering and physics to commercialization inspired the writing of this book. The authors' experiences in applying Robust Design to mechanical and electrical systems, electrophotographic process optimization, and chemical process optimization at Kodak have demonstrated convincingly that Dr. Taguchi's design optimization techniques are extremely effective in reducing cycle time and rework. Every company that employs Robust Design does so in the context of their own internal culture. Only the books written by Dr. Taguchi follow his views in totality. This book is a reflection of how we have internalized Dr. Taguchi's insights and teachings into our culture at Kodak. In this industrial environment, we have found broad acceptance and a strong willingness to employ Taguchi methods when practiced in an engineering context. This, of course, is exactly how Dr. Taguchi and those who have listened to him over the years approach the topic - as an engineering process. The successes experienced at Kodak and at many other companies we have encountered are derived from Dr. Taguchi's advice T6: "Spend about 80% of your time in engineering analysis and planning and about 20% actually running experiments and evaluating the results."
Recently, engineering process improvement has been introduced into the academic arena. Courses on Robust Design, QFD, Six Sigma, and other quality processes can now be found at an increasing number of schools. Some of the leaders in this new trend include the Massachusetts Institute of Technology, Stanford University, Georgia Institute of Technology, and Michigan Technological University. Rochester Institute of Technology (RIT), where we teach and serve on the Industrial Advisory Board, recently adopted elements of a quality engineering curriculum as mechanical engineering electives. This book is largely based on our experience in teaching the Robust Design course at RIT in an engineering department. This is unique, because much of the academic attention given to Dr. Taguchi's methods has come from the statistics community as a result of Dr. Taguchi's use of empirical statistical techniques, particularly design of experiments. This has led to a misunderstanding of robust design as being statistical in nature. This book takes an entirely fresh look at robust design as an engineering process, where the emphasis is on using engineering analysis to improve product performance.
This book offers simple, yet effective, guidelines on how to practice robust design in the context of a total quality development effort. In these pages, the fundamental metrics of quality engineering are fully developed, and the rationale behind them is explained. Designing low-cost solutions is a given requirement. We discuss the impact of robust design on the cost of a design, as well as how cost and quality can be co-optimized using Dr. Taguchi's Quality Loss Function. The fundamental statistical tools (e.g., design of experiments, analysis of variance, and analysis of interactions) are explained in what we hope will be an intuitive yet mathematically precise way. A healthy balance exists between the statistical sciences and the engineering sciences. In this book, we try to introduce practical insight into the statistical side of Robust Design, while maintaining the hightest priority in basing the experimental approach on sound engineering principles. The most important element of engineering success is clear thinking, planning, analysis, and communication. For this reason, we offer this book primarily as a guide on how to invest your time efficiently in the 80% up-front engineering required, particularly as it pertains to technology development and product commercialization.
The Structure of This Book
Chapter 1 is organized to provide a broad introduction to Quality Engineering and to establish the fundamental concepts needed to build the reader's understanding for work presented in later chapters.The rest of the book is presented in three major parts. The first is an introduction to Quality Engineering Metrics. It consists of Chapters 2 through 6. Robust Design is a data driven process. Chapter 2 goes through Introductory Data Analysis for Robust Design and is presented to establish a context for how data will be treated throughout the rest of the book. Chapter 3 presents the theory and derivation of the various forms of the Quality Loss Function. An application of the quality loss function to tolerance design is also included. Chapter 4 presents the fundamental knowledge behind the Signal-to-Noise Ratio. The static and dynamic signal-to-noise ratios are fully discussed with numerous examples in Chapters 5 and 6, respectively.
The second part delves into the details of the parameter design process with a special emphasis on achieving additivity.1 Additivity is a property of a design that reduces harmful interactions,1 thus simplifying the optimization process. Chapter 7 is a practical Introduction to Designed Experiments. Without the use of designed experiments, the process of optimizing a product becomes a time consuming endeavor laced with rework and unwanted surprises due to interactions. Chapter 8 is focused on a thorough discussion concerning the Selection of the Quality Characteristics. Few choices in the process of quality engineering are as critical as the selection of the physical responses to be measured during the designed experiments. Chapter 9 provides a sound basis for the Selection and Testing of Noise Factors to stress the design during the development of robustness. Constructing viable noise factor experiments is an indispensable step in preparing for credible and realistic optimization experiments. Chapter 10 completes the discuss
