Design of Experiments for Engineers and Scientists SECOND EDITION Jiju Antony School of Management and Languages, Heriot-Watt University, Edinburgh, Scotland, UK Table of Contents Cover image Title page Copyright Preface Acknowledgements 1. Introduction to Industrial Experimentation 1.1 Introduction 1.2 Some Fundamental and Practical Issues in Industrial Experimentation 1.3 Statistical Thinking and its Role Within DOE Exercises References 2. Fundamentals of Design of Experiments 2.1 Introduction 2.2 Basic Principles of DOE 2.3 Degrees of Freedom 2.4 Confounding 2.5 Selection of Quality Characteristics for Industrial Experiments Exercises References 3. Understanding Key Interactions in Processes 3.1 Introduction 3.2 Alternative Method for Calculating the Two-Order Interaction Effect 3.3 Synergistic Interaction Versus Antagonistic Interaction 3.4 Scenario 1 3.5 Scenario 2 3.6 Scenario 3 Exercises References 4. A Systematic Methodology for Design of Experiments 4.1 Introduction 4.2 Barriers in the Successful Application of DOE 4.3 A Practical Methodology for DOE 4.4 Analytical Tools of DOE 4.5 Model Building for Predicting Response Function 4.6 Confidence Interval for the Mean Response 4.7 Statistical, Technical and Sociological Dimensions of DOE Exercises References 5. Screening Designs 5.1 Introduction 5.2 Geometric and Non-geometric P–B Designs Exercises References 6. Full Factorial Designs 6.1 Introduction 6.2 Example of a 22 Full Factorial Design 6.3 Example of a 23 Full Factorial Design 6.4 Example of a 24 Full Factorial Design Exercises References 7. Fractional Factorial Designs 7.1 Introduction 7.2 Construction of Half-Fractional Factorial Designs 7.3 Example of a 2(7−4) Factorial Design 7.4 An Application of 2-Level Fractional Factorial Design Exercises References 8. Some Useful and Practical Tips for Making Your Industrial Experiments Successful 8.1 Introduction Exercises References 9. Case Studies 9.1 Introduction 9.2 Case Studies References 10. Design of Experiments and its Applications in the Service Industry 10.1 Introduction to the Service Industry 10.2 Fundamental Differences Between the Manufacturing and Service Organisations 10.3 DOE in the Service Industry: Fundamental Challenges 10.4 Benefits of DOE in Service/Non-Manufacturing Industry 10.5 DOE: Case Examples from the Service Industry 10.6 Role of Computer Simulation Models Within DOE Exercises References 11. Design of Experiments and its Role Within Six Sigma 11.1 What is Six Sigma? 11.2 How Six Sigma is Different from Other Quality Improvement Initiatives of the Past 11.3 Who Makes Six Sigma Work? 11.4 Six Sigma Methodology (DMAIC Methodology) 11.5 DOE and Its Role Within Six Sigma Exercises References Copyright Elsevier 32 Jamestown Road, London NW1 7BY 225 Wyman Street, Waltham, MA 02451, USA First edition 2003 Second edition 2014 Copyright © 2014, 2003 Jiju Antony. Published by Elsevier Ltd. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. 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Preface Design of Experiments (DOE) is a powerful technique used for both exploring new processes and gaining increased knowledge of existing processes, followed by optimising these processes for achieving world-class performance. My involvement in promoting and training in the use of DOE dates back to the mid- 1990s. There are plenty of books available in the market today on this subject written by classic statisticians, although the majority of them are better suited to other statisticians than to run-of-the-mill industrial engineers and business managers with limited mathematical and statistical skills. DOE never has been a favourite technique for many of today’s engineers and managers in organisations due to the number crunching involved and the statistical jargon incorporated into the teaching mode by many statisticians. This book is targeted to people who have either been intimidated by their attempts to learn about DOE or who have never appreciated the true potential of DOE for achieving breakthrough improvements in product quality and process efficiency. This book gives a solid introduction to the technique through a myriad of practical examples and case studies. The second edition of the book has incorporated two new chapters and both cover the latest developments on the topic of DOE. Readers of this book will develop a sound understanding of the theory of DOE and practical aspects of how to design, analyse and interpret the results of a designed experiment. Throughout this book, the emphasis is on the simple but powerful graphical tools available for data analysis and interpretation. All of the graphs and figures in this book were created using Minitab version 15.0 for Windows. I sincerely hope that practising industrial engineers and managers as well as researchers in academic world will find this book useful in learning how to apply DOE in their own work environment. The book will also be a useful resource for people involved in Six Sigma training and projects related to design optimisation and process performance improvements. In fact, I have personally observed that the number of applications of DOE in non-manufacturing sectors has increased significantly because of the methodology taught to Six Sigma professionals such as Six Sigma Green Belts and Black Belts. The second edition has a chapter dedicated to DOE for non-manufacturing processes. As a mechanical engineer, I was not convinced about the application of DOE in the context of the service industry and public sector organisations including Higher Education. I have included a simple case study showing the power of DOE in a university setting. I firmly believe that DOE can be applied to any industrial setting, although there will be more challenges and barriers in the non-manufacturing sector compared to traditional manufacturing companies. I hope that this book inspires readers to get into the habit of applying DOE for problem-solving and process troubleshooting. I strongly recommend that readers of this book continue on a more advanced reference to learn about topics which are not covered here. I am indebted to many contributors and gurus for the development of various experimental design techniques, especially Sir Ronald Fisher, Plackett and Burman, Professor George Box, Professor Douglas Montgomery, Dr Genichi Taguchi and Dr Dorian Shainin.
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