Statistical process control

Statistical process control is a tool which enables both manufacturers and suppliers to achieve control of product quality by applying statistical methods to controlling processes. This guide provides an introduction to the concept. The business, commercial and public-sector world has changed dramatically since John Oakland wrote the first edition of Statistical Process Control - a practical guide in the mid-eighties. Then people were rediscovering statistical methods of `quality control' and the book responded to an often desperate need to find out about the techniques and use them on data. Pressure over time from organizations supplying directly to the consumer, typically in the automotive and high technology sectors, forced those in charge of the supplying production and service operations to think more about preventing problems than how to find and fix them. Subsequent editions retained the `took kit' approach of the first but included some of the `philosophy' behind the techniques and their use. The theme which runs throughout the 7th edition is still processes - that require understanding, have variation, must be properly controlled, have a capability, and need improvement - the five sections of this new edition. SPC never has been and never will be simply a `took kit' and in this book the authors provide, not only the instructional guide for the tools, but communicate the management practices which have become so vital to success in organizations throughout the world. The book is supported by the authors' extensive and latest consulting work within thousands of organisations worldwide. Fully updated to include real-life case studies, new research based on client work from an array of industries, and integration with the latest computer methods and Minitab software, the book also retains its valued textbook quality through clear learning objectives and end of chapter discussion questions. It can still serve as a textbook for both student and practicing engineers, scientists, technologists, managers and for anyone wishing to understand or implement modern statistical process control techniques Statistical Process Control- Front Cover Half Title Title Page Copyright Page Dedication Contents Preface Other titles by the same author and publisher PART I: Process understanding Chapter 1: Quality, processes and control Objectives 1.1 The basic concepts 1.2 Design, conformance and costs 1.3 Quality, processes systems, teams, tools and SPC 1.4 Some basic tools Chapter highlights Note References and further reading Discussion questions Chapter 2: Understanding the process Objectives 2.1 Improving customer satisfaction through process management 2.2 Information about the process 2.3 Process mapping and flowcharting 2.4 Process analysis 2.5 Statistical process control and process understanding Chapter highlights Note References and further reading Discussion questions Chapter 3: Process data collection and presentation Objectives 3.1 The systematic approach 3.2 Data collection 3.3 Bar charts and histograms 3.4 Graphs, run charts and other pictures 3.5 Conclusions Chapter highlights References and further reading Discussion questions PART II: Process variability Chapter 4: Variation: understanding and decision making Objectives 4.1 How some managers look at data 4.2 Interpretation of data 4.3 Causes of variation 4.4 Accuracy and precision 4.5 Variation and management Chapter highlights References and further reading Discussion questions Chapter 5: Variables and process variation Objectives 5.1 Measures of accuracy or centring 5.2 Measures of precision or spread 5.3 The normal distribution 5.4 Sampling and averages Chapter highlights References and further reading Discussion questions Worked examples using the normal distribution PART III: Process control Chapter 6: Process control using variables Objectives 6.1 Means, ranges and charts 6.2 Are we in control? 6.3 Do we continue to be in control? 6.4 Choice of sample size and frequency, and control limits 6.5 Short-, medium- and long-term variation: a change in the standard practice 6.6 Summary of SPC for variables using X and R charts Chapter highlights References and further reading Discussion questions Worked examples Chapter 7: Other types of control charts for variables Objectives 7.1 Life beyond the mean and range chart 7.2 Charts for individuals or run charts 7.3 Median, mid-range and multi-vari charts 7.4 Moving mean, moving range and exponentially weighted moving average (EWMA) charts 7.5 Control charts for standard deviation (σ) 7.6 Techniques for short run SPC 7.7 Summarizing control charts for variables Chapter highlights Note References and further reading Discussion questions Worked example Chapter 8: Process control by attributes Objectives 8.1 Underlying concepts 8.2 np-charts for number of defectives or non-conforming units 8.3 p-charts for proportion defective or non-conforming units 8.4 c-charts for number of defects/non-conformities 8.5 u-charts for number of defects/non- conformities per unit 8.6 Attribute data in non-manufacturing Chapter highlights References and further reading Discussion questions Worked examples Chapter 9: Cumulative sum (cusum) charts Objectives 9.1 Introduction to cusum charts 9.2 Interpretation of simple cusum charts 9.3 Product screening and pre-selection 9.4 Cusum decision procedures Chapter highlights References and further reading Discussion questions Worked examples PART IV: Process capability Chapter 10: Process capability for variables and its measurement Objectives 10.1 Will it meet the requirements? 10.2 Process capability indices 10.3 Interpreting capability indices 10.4 The use of control chart and process capability data 10.5 A service industry example: process capability analysis in a bank Chapter highlights References and further reading Discussion questions Worked examples PART V: Process improvement Chapter 11: Process problem solving and improvement Objectives 11.1 Introduction 11.2 Pareto analysis 11.3 Cause and effect analysis 11.4 Scatter diagrams 11.5 Stratification 11.6 Summarizing problem solving and improvement Chapter highlights References and further reading Discussion questions Worked examples Chapter 12: Managing out-of-control processes Objectives 12.1 Introduction 12.2 Process improvement strategy 12.3 Use of control charts for trouble-shooting 12.4 Assignable or special causes of variation Chapter highlights References and further reading Discussion questions Chapter 13: Designing the statistical process control system Objectives 13.1 SPC and the quality management system 13.2 Teamwork and process control/improvement 13.3 Improvements in the process 13.4 Taguchi methods 13.5 Summarizing improvement Chapter highlights References and further reading Discussion questions Chapter 14: Six-sigma process quality Objectives 14.1 Introduction 14.2 The six-sigma improvement model 14.3 Six-sigma and the role of Design of Experiments 14.4 Building a six-sigma organization and culture 14.5 Ensuring the financial success of six-sigma projects 14.6 Concluding observations and links with Excellence Chapter highlights References and further reading Discussion questions Chapter 15: The implementation of statistical process control Objectives 15.1 Introduction 15.2 Successful users of SPC and the benefits derived 15.3 The implementation of SPC 15.4 Proposed methodology for implementation Acknowledgements Chapter highlights References and further reading Appendices Appendix A: The normal distribution and non-normality Appendix B: Constants used in the design of control charts for mean Appendix C: Constants used in the design of control charts for range Appendix D: Constants used in the design of control charts for median and range Appendix E: Constants used in the design of control charts for standard deviation Appendix F: Cumulative Poisson probability curves Appendix G: Confidence limits and tests of significance Appendix H: OC curves and ARL curvesfor X and R charts Appendix I: Autocorrelation Appendix J: Approximations to assist in process control of attributes Appendix K: Glossary of terms and symbols Index