Statistical Process Control

Contents......Page 5
Preface......Page 11
Part 1 Process Understanding......Page 15
1.1 The basic concepts......Page 17
1.2 Design, conformance and costs......Page 22
1.3 TQM, processes and the SPC system......Page 28
1.4 Some basic tools......Page 31
2.1 Improving customer satisfaction through process management......Page 37
2.2 Information about the process......Page 40
2.3 Process mapping and flowcharting......Page 43
2.4 Process analysis......Page 49
2.5 Statistical process control and process understanding......Page 51
3.1 The systematic approach......Page 56
3.2 Data collection......Page 58
3.3 Bar charts and histograms......Page 60
3.4 Graphs, run charts and other pictures......Page 68
3.5 Conclusions......Page 71
Part 2 Process Variability......Page 75
4.1 The way managers look at data......Page 77
4.2 Interpretation of data......Page 78
4.3 Causes of variation......Page 82
4.4 Accuracy and precision......Page 86
4.5 Variation and management......Page 91
5.1 Measures of accuracy or centring......Page 96
5.2 Measures of precision or spread......Page 99
5.3 The normal distribution......Page 102
5.4 Sampling and averages......Page 103
Part 3 Process Control......Page 117
6.1 Means, ranges and charts......Page 119
6.2 Are we in control?......Page 132
6.3 Do we continue to be in control?......Page 134
6.4 Choice of sample size and frequency, and control limits......Page 137
10.5 A service industry example Ò process capability analysis in a bank......Page 0
6.6 Summary of SPC for variables using X and R charts......Page 144
7.1 Life beyond the mean and range chart......Page 167
7.2 Charts for individuals or run charts......Page 169
7.3 Median, mid-range and multi-vari charts......Page 175
7.4 Moving mean, moving range, and exponentially weighted moving average ( EWMA) charts......Page 179
7.5 Control charts for standard deviation (......Page 190
7.6 Techniques for short run SPC......Page 196
7.7 Summarizing control charts for variables......Page 198
8.1 Underlying concepts......Page 209
8.2 np-charts for number of defectives or non-conforming units......Page 212
8.3 p-charts for proportion defective or non-conforming units......Page 220
8.4 c-charts for number of defects/non-conformities......Page 224
8.5 u-charts for number of defects/non-conformities per unit......Page 228
8.6 Attribute data in non-manufacturing......Page 229
9.1 Introduction to cusum charts......Page 241
9.2 Interpretation of simple cusum charts......Page 245
9.3 Product screening and pre-selection......Page 250
9.4 Cusum decision procedures......Page 251
Part 4 Process Capability......Page 271
10.1 Will it meet the requirements?......Page 273
10.2 Process capability indices......Page 275
10.3 Interpreting capability indices......Page 280
10.4 The use of control chart and process capability data......Page 281
Part 5 Process Improvement......Page 289
11.1 Introduction......Page 291
11.2 Pareto analysis......Page 294
11.3 Cause and effect analysis......Page 303
11.4 Scatter diagrams......Page 310
11.5 Stratification......Page 312
11.6 Summarizing problem solving and improvement......Page 314
12.1 Introduction......Page 329
12.2 Process improvement strategy......Page 330
12.3 Use of control charts for trouble-shooting......Page 332
12.4 Assignable or special causes of variation......Page 343
13.1 SPC and the management system......Page 348
13.2 Teamwork and process control/improvement......Page 352
13.3 Improvements in the process......Page 354
13.4 Taguchi methods......Page 361
13.5 Summarizing improvement......Page 367
14.1 Introduction......Page 370
14.2 The six-sigma improvement model......Page 373
14.3 Six-sigma and the role of Design of experiments......Page 374
14.4 Building a six-sigma organization and culture......Page 378
14.5 Ensuring the financial success of six-sigma projects......Page 380
14.6 Concluding observations and links with Excellence......Page 387
15.1 Introduction......Page 392
15.2 Successful users of SPC and the benefits derived......Page 393
15.3 The implementation of SPC......Page 394
Appendix A The normal distribution and non-normality......Page 400
Appendix B Constants used in the design of control charts for mean......Page 410
Appendix C......Page 411
Appendix D Constants used in the design of control charts for median and range......Page 412
Appendix E Constants used in the design of control charts for standard deviation......Page 413
Appendix F......Page 414
Appendix G Confidence limits and tests of significance......Page 425
Appendix H OC curves and ARL curves for X and R charts......Page 435
Appendix I Autocorrelation......Page 440
Appendix J Approximations to assist in process control of attributes......Page 442
Appendix K Glossary of terms and symbols......Page 447
Index......Page 455