The Certified Six Sigma Green Belt Handbook Second Edition Roderick A. Munro, Govindarajan Ramu, and Daniel J. Zrymiak ASQ Quality Press Milwaukee, Wisconsin American Society for Quality, Quality Press, Milwaukee 53203 © 2015 by ASQ All rights reserved. Published 2015 Printed in the United States of America 21 20 19 18 17 16 15 5 4 3 2 1 Library of Congress Cataloging-in-Publication Data Munro, Roderick A. The certified six sigma green belt handbook / Roderick A. Munro, Govindarajan Ramu, and Daniel J. Zrymiak.—Second edition. pages cm Revised edition of: The certified six sigma green belt handbook / Roderick A. Munro . . . [et al.]. c2008. Includes bibliographical references and index. ISBN 978-0-87389-891-1 (hard cover : alk. paper) 1. Six sigma (Quality control standard)—Handbooks, manuals, etc. 2. Production management—Handbooks, manuals, etc. 3. Quality control—Statistical methods— Handbooks, manuals, etc. I. Ramu, Govindarajan. II. Zrymiak, Daniel J. III. Title. TS156.C4235 2015 658.5—dc23 2014046292 ISBN 978-0-87389-891-1 No part of this book may be reproduced in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Publisher: Lynelle Korte Acquisitions Editor: Matt T. Meinholz Managing Editor: Paul Daniel O’Mara Production Administrator: Randall Benson ASQ Mission: The American Society for Quality advances individual, organizational, and community excellence worldwide through learning, quality improvement, and knowledge exchange. Attention Bookstores, Wholesalers, Schools, and Corporations: ASQ Quality Press books, video, audio, and software are available at quantity discounts with bulk purchases for business, educational, or instructional use. For information, please contact ASQ Quality Press at 800-248-1946, or write to ASQ Quality Press, P.O. Box 3005, Milwaukee, WI 53201-3005. To place orders or to request ASQ membership information, call 800-248-1946. Visit our website at http://www.asq.org/quality-press. Printed on acid-free paper Michael J. cleary Founder of PQ Systems, Inc. Born June 3, 1939 Died suddenly on September 10, 2014 Dr. Cleary, a noted authority in the field of quality management and a charter member of the Education Division of the American Society for Quality Control (now ASQ), founded PQ Systems, Inc., in 1984, with headquarters in Dayton, Ohio, later opening PQ Systems Europe Ltd., with sales in continental Europe and the Middle East, and PQ Systems Pty Ltd. in Frankston, Australia, serving the Pacific Rim. The company’s products help organizations demonstrate proof of the q uality of their products and services using statistical methods and problem-solving tools. PQ Systems was named among the top 25 best places to work in Dayton in 2014. Cleary played a principal role in developing the Transformation of Ameri- can Industry national training project, as well as the Total Quality Transforma- tion training system. He served on the planning committee for the U.S.–Japanese Business Conference in Tokyo, and presented papers on statistical process control and the applications of quality management principles to a variety of audiences in Korea, China, France, Great Britain, Australia, Singapore, and Japan. He was the author of A Data Analysis Handbook: Using the SPSS System, as well as coeditor of Practical Tools for Continuous Improvement, volumes 1 and 2. As a professor of management science at Wright State University from 1971– 1996, Cleary was awarded the Business College Associates Alumni Teaching Award. His 25-year professorship in management science enabled Cleary to con- duct extensive research and garner valuable experience in expanding quality management methods. He was a leader in bringing quality management into the curriculum of the College of Business, and published articles and papers on issues vi Dedication related to quality management, statistical applications, and decision sciences in a variety of academic and professional journals. Cleary is survived by his wife of 50 years, Barbara A. Cleary, PhD, and their four sons: Sean (Katherine St. John), Timothy (Laura Jackson), Matthew (Liz Hansen), and Dennis (Karina Johansen), grandsons Michael Wyatt Cleary, Harmon Hemp- stead Cleary, Daniel St. John Cleary, and Victor Thomas Cleary, granddaugh- ter Johanna Sol Cleary, sister Joan Buckman, brother-in-law John Rathman, and nieces and nephews. list of Figures and Tables Table 1.1 Some approaches to quality over the years. ........................... 5 Figure 1.1 Example of a process flowchart. ..................................... 16 Figure 1.2 Relationships between systems, processes, subprocesses, and steps. ..... 17 Figure 1.3 A feedback loop. .................................................. 17 Figure 1.4 Categories of inputs to a process step. ................................ 18 Figure 1.5 Traditional quality cost curves. ...................................... 24 Figure 1.6 Modern quality cost curves. ........................................ 25 Table 1.2 Risk analysis table. ................................................ 27 Figure 1.7 A format for SWOT analysis. ........................................ 27 Figure 2.1 TPS house. ........................................................ 32 Figure 2.2 7S adaptation (Hirano). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Figure 2.3 A sea of inventory often hides unresolved problems. ................... 42 Figure 2.4 C-shaped manufacturing cell. ....................................... 43 Figure 2.5 Common symbols used in value stream mapping. ..................... 46 Figure 2.6 Value stream map example. ......................................... 47 Table 3.1 Design objectives and outputs traceability matrix. ..................... 54 Figure 3.1 Simple risk matrix. ................................................ 57 Figure 3.2 Sample DFMEA headers. ........................................... 59 Figure 3.3 Sample PFMEA headers. ........................................... 60 Figure 3.4 FMEA flowchart. .................................................. 61 Figure 3.5 FMEA flowchart in line with common FMEA form. .................... 62 Table 3.2 Steps in performing a design or process FMEA. ....................... 63 Table 3.3 Possible severity evaluation criteria. ................................. 65 Table 3.4 Possible occurrence evaluation criteria. ............................... 65 Table 3.5 Possible detection evaluation criteria. ................................ 65 Figure 3.6 Example of RPN calculations. ....................................... 66 Figure 3.7 Example of FMEA reporting and RPN chart. .......................... 68 Figure 3.8 A typical risk action plan Gantt chart. ................................ 68 Figure 3.9 A typical top-level management review report for FMEA progress. ...... 69 Figure 3.10 An example of a partially filled-in FMEA. ............................ 70 Figure 3.11 This example of a tree diagram is a fault tree (used to study defects and failures). ..................................................... 71 xvi List of Figures and Tables xvii Figure 3.12 Common types of FMEA. ........................................... 71 Figure 4.1 Process diagram/model. ........................................... 77 Table 4.1 Tips for benchmarking. ............................................ 80 Figure 4.2 Basic SIPOC diagram. .............................................. 82 Figure 5.1 Example of a QFD matrix for an animal trap. .......................... 89 Figure 5.2 Map to the entries of the QFD matrix illustrated in Figure 5.1. ........... 90 Figure 5.3 Sequence of QFD matrices for product, part, and process planning. ...... 90 Figure 5.4 Example of a completed QFD matrix. ................................ 92 Figure 5.5 QFD stage flow and relationships. ................................... 93 Figure 5.6 QFD input–output requirements matrix. ............................. 93 Table 5.1 QFD value characteristics. .......................................... 94 Figure 6.1 Risk assessment assignment matrix. ................................. 100 Figure 7.1 Example of an activity network diagram. ............................. 103 Figure 7.2 Example of an affinity diagram. ..................................... 104 Figure 7.3 Example of a cause-and-effect diagram. .............................. 108 Figure 7.4 Example of a check sheet. ........................................... 109 Figure 7.5 High-level flowchart for an order-filling process. ...................... 110 Figure 7.6 Detailed flowchart for the order-filling process. ....................... 111 Figure 7.7 Example of force-field analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Figure 7.8 Gantt chart example. ............................................... 112 Figure 7.9 Graphical representation of question responses. ....................... 114 Figure 7.10 Example interrelationship digraph. .................................. 116 Figure 7.11 Example matrix diagram. ........................................... 117 Figure 7.12 PDCA cycle. ...................................................... 118 Figure 7.13 Prioritization matrix example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Figure 7.14 Example process decision program chart (PDPC). ..................... 121 Figure 7.15 PERT/critical path chart example. ................................... 122 Figure 7.16 SIPOC diagram with requirements capture. .......................... 124 Figure 7.17 This example of a tree diagram is a fault tree (used to study defects and failures). ..................................................... 125 Table 9.1 Common negative team dynamics and potential countermeasures. ...... 136 Figure 9.1 Typical large Six Sigma organization. ................................ 140 Figure 9.2 Typical small Six Sigma organization. ................................ 141 Table 9.2 Typical Six Sigma roles. ............................................ 141 Figure 9.3 Multivoting ranked approach example. .............................. 151 Figure 9.4 Multivoting weighted approach example. ............................. 152 Figure 10.1 Symbols commonly used in flowcharts and process maps. .............. 155 Figure 10.2 Basic flowchart for warranty product replacement. .................... 156 Figure 10.3 Cross-functional or swim lane flowchart. ............................. 157 Figure 10.4 Empty cause-and-effect diagram. .................................... 161 xviii List of Figures and Tables Figure 10.5 Cause-and-effect diagram after a few steps of a brainstorming session. ... 161 Figure 10.6 Pareto chart of final assembly inspection defect codes. ................. 163 Figure 10.7 Pareto chart of final assembly inspection defect codes (weighted). ....... 164 Figure 10.8 Example of a Pareto chart of a too-detailed defect summary. ............ 165 Figure 10.9 Example of a measles chart (pictorial check sheet). ..................... 166 Figure 10.10 Relationship matrix. ............................................... 167 Figure 11.1 Venn diagram. .................................................... 169 Figure 11.2 Mutually exclusive events. .......................................... 171 Figure 11.3 Various populations and sampling distributions of the mean for selected sample sizes. .............................................. 175 Table 11.1 Descriptive versus analytical statistics. ............................... 177 Table 11.2 Sample versus population notations. ................................. 178 Table 12.1 Formula, mean, and variance of certain distributions. ................... 179 Figure 12.1 Binomial distribution. ............................................. 180 Figure 12.2 Binomial distribution using Microsoft Excel. .......................... 181 Figure 12.3 Poisson distribution. ............................................... 183 Figure 12.4 Poisson distribution using Microsoft Excel. ........................... 184 Figure 12.5 Normal distribution curve. ......................................... 185 Figure 12.6 Normal probability density function and cumulative density function. ......................................................... 185 Figure 12.7 Chi-square distribution example. .................................... 188 Figure 12.8 F-distribution with varying degrees of freedom. . . . . . . . . . . . . . . . . . . . . . . . 191 Table 13.1 Measurement scales. ............................................... 193 Table 13.2 Coding–decoding. ................................................. 196 Figure 13.1 Example of a check sheet. ........................................... 197 Figure 13.2 Example of a data set as illustrated by a frequency distribution, individual plot, histogram, and probability plot. ....................... 198 Figure 13.3 Cumulative frequency distribution in table and graph form. ............ 200 Table 13.3 Comparison of various graphical methods. ........................... 201 Figure 13.4 Histogram and stem-and-leaf plot comparison. ........................ 204 Figure 13.5 Box plot. .......................................................... 205 Figure 13.6 Example box plot. ................................................. 205 Figure 13.7 Box plots versus dot plots. .......................................... 206 Table 13.4 Example of yield data from three periods. ............................ 206 Figure 13.8 Box plot by period. ................................................ 207 Figure 13.9 Run chart analysis (using statistical software). ........................ 208 Figure 13.10 Scatter diagrams. .................................................. 209 Table 13.5 Mold process data. ................................................. 210 Figure 13.11 Examples of scatter diagrams (variables versus effects). ................ 210 Figure 13.12 Correlation between variables and effects (using statistical software). .... 211 Figure 13.13 Example scatter plots—exercise versus weight loss. .................... 212 List of Figures and Tables xix Figure 13.14 Normal probability plot. ............................................ 214 Figure 13.15 Example of Weibull plot. ........................................... 216 Figure 14.1 Gage repeatability. ................................................. 218 Figure 14.2 Gage reproducibility. .............................................. 219 Figure 14.3 Gage R&R data collection sheet. ..................................... 220 Figure 14.4 Gage R&R data collection sheet with data entered and calculations completed. ........................................................ 222 Figure 14.5 Gage repeatability and reproducibility report. . . . . . . . . . . . . . . . . . . . . . . . . . 223 Figure 14.6 Gage repeatability and reproducibility report with calculations. ......... 224 Figure 14.7 Example gage repeatability and reproducibility analysis. ............... 225 Figure 14.8 GR&R report using statistical software. .............................. 226 Figure 14.9 Sources of measurement variation. .................................. 227 Figure 14.10 Observed versus actual capability. ................................... 227 Figure 14.11 GR&R sample selection. ............................................ 228 Table 14.1 GR&R random Excel sheet example. ................................. 229 Table 14.2 Measurement test data for linearity and bias. ......................... 231 Figure 14.12 Linearity and bias analysis using statistical software. .................. 232 Figure 14.13 Minitab orthogonal regression example. .............................. 233 Figure 14.14 Attribute agreement analysis using statistical software. ................ 234 Figure 15.1 Control limit versus specification limit grid. .......................... 238 – Figure 15.2 Example of X and R control chart. ................................... 238 Figure 15.3 Process capability report for shaft machining. ......................... 243 Figure 15.4 Types of sampling for SPC data collection. ............................ 244 Figure 15.5 Process capability scenarios. ........................................ 246 Figure 15.6 Process performance indices P , P , and C . ......................... 249 p pk pm Figure 15.7 Process performance 1.5-sigma shift. ................................. 250 Figure 15.8 Short-term versus long-term performance with 1.5-sigma shift. .......... 251 Table 16.1 Types of variation. ................................................. 255 Figure 16.1 Variation within samples. .......................................... 255 Figure 16.2 Excessive variability (part is tapered). ................................ 256 Figure 16.3 Less variability (center is thicker). ................................... 256 Figure 16.4 Variability shift over time (part is getting larger). ...................... 256 Figure 16.5 Stainless steel casting with critical inner diameter. ..................... 257 Figure 16.6 Sectional views of stainless steel casting. ............................. 258 Figure 16.7 Data collection sheet. .............................................. 259 Table 16.2 Measurement data from five parts produced during one shift. .......... 259 Figure 16.8 Graph of data from Table 16.2. ....................................... 259 Figure 16.9 Part-to-part variation (graph of data from Table 16.2). .................. 260 Table 16.3 Data from five parts produced during one shift using precision castings. .......................................................... 260 Figure 16.10 Graph of data from Table 16.3. ....................................... 261 xx List of Figures and Tables Figure 16.11 Graph of data from Table 16.3 with orientation measurement numbers. ......................................................... 262 Table 16.4 Data from five parts after pressure-washing. .......................... 262 Table 16.5 Examples of dependent and independent variables. .................... 263 Figure 16.12 The four types of correlation in scatter plots. .......................... 264 Table 16.6 Data table for correlation calculation. ................................ 267 Figure 16.13 CORREL function in Excel. ......................................... 269 Table 16.7 Least squares example. ............................................. 271 Figure 16.14 Regression dialog box. ............................................. 273 Figure 16.15 Regression data analysis. ........................................... 273 Figure 16.16 Simple regression results. ........................................... 274 Figure 16.17 A schematic showing variation in y as a function of x. .................. 277 Table 17.1 Error matrix. ...................................................... 280 Figure 17.1 One-tail test: (a) right-tailed test and (b) left-tailed test. ................. 281 Figure 17.2 Two-tail test. ...................................................... 282 Figure 17.3 Power curve. ...................................................... 285 Figure 17.4 Excel’s FINV function. ............................................. 306 Figure 17.5 Setting up a one-way ANOVA in Excel. ............................... 306 Figure 17.6 The ANOVA: Single Factor dialog box. ............................... 307 Figure 17.7 Final results of one-way ANOVA in Excel. ............................ 307 Figure 17.8 Expected versus observed chart (Minitab output). ..................... 309 Figure 17.9 Excel’s CHINV function. ........................................... 311 Figure 18.1 Main effects graphs. ............................................... 324 Table 18.1 A 23 full factorial design using + and – format. ........................ 325 Table 18.2 A 23 full factorial design showing interaction columns. ................. 326 Table 18.3 Half fraction of 23 (also called a 23–1 design). ........................... 327 Table 18.4 Half fraction of 23 design with interaction columns filled in. ............ 327 Table 18.5 Latin square design. ............................................... 329 Figure 18.2 Graph of temperature and moisture content. .......................... 330 Table 18.6 A 22 full factorial completely randomized experiment with results. ...... 330 Table 18.7 A 22 full factorial completely randomized experiment with main and interaction effects. ................................................. 331 Table 18.8 ANOVA outcomes. ................................................ 337 Figure 19.1 Comparative analysis. .............................................. 345 Figure 19.2 Cause-and-effect relational matrix. .................................. 346 Figure 19.3 Root cause tree example. ........................................... 347 Figure 20.1 Project framework. ................................................ 350 Figure 20.2 Lean Six Sigma objectives. .......................................... 350 Figure 20.3 Poka-yoke example. ................................................ 353 Figure 21.1 Average shifting, variation stable. ................................... 378 Figure 21.2 Average stable, variation changing. .................................. 379 List of Figures and Tables xxi Figure 21.3 Average shifting, variation changing. ................................ 379 Figure 21.4 Average stable, variation stable. ..................................... 380 Figure 21.5 An operating characteristic (OC) curve. .............................. 382 – Figure 21.6 X and R control chart example with data plotted. ...................... 383 Figure 21.7 Rational subgrouping. ............................................. 387 Figure 21.8 Rational subgrouping with randomness. ............................. 388 – Figure 21.9 Measurement data entered in an X and R control chart. ................ 391 – Figure 21.10 Completed X and R control chart. ................................... 392 – Figure 21.11 Example of an X and s control chart. ................................. 393 Figure 21.12 Example of an individuals and moving range control chart. ............. 394 Figure 21.13 Example of a median control chart with associated range gage. .......... 396 Figure 21.14 Example of a p-chart. .............................................. 398 Figure 21.15 Example of an np-chart. ............................................ 400 Figure 21.16 Example of a u-chart. .............................................. 401 Figure 21.17 Example of a c-chart. ............................................... 403 Figure 21.18 One point more than 3σ from the centerline (either side) ............... 406 Figure 21.19 Nine points in a row on the same side of the centerline ................. 406 Figure 21.20 Six points in a row all increasing or decreasing. ....................... 407 Figure 21.21 Fourteen points in a row alternating up and down. .................... 407 Figure 21.22 Two out of three points more than 2σ from the centerline (same side). .... 407 Figure 21.23 Four out of five points more than 1σ from the centerline (same side). ..... 408 Figure 21.24 Fifteen points in a row within 1σ of the centerline (either side). .......... 408 Figure 21.25 Eight points in a row more than 1σ from the centerline (either side). ..... 408 Figure 21.26 Points beyond the control limits. .................................... 409 Figure 21.27 Seven points in a row on one side of the average. ...................... 409 Figure 21.28 Seven points in a row that are consistently increasing or consistently decreasing. ....................................................... 409 Figure 21.29 Over 90 percent of plotted points are in the middle third of the control limit region (for 25 or more subgroups). ....................... 410 Figure 21.30 Fewer than 40 percent of the plotted points are in the middle third of the control limit region (for 25 or more subgroups). .................... 410 Figure 21.31 Obvious nonrandom patterns such as cycles. .......................... 410 Figure 22.1 A sample control plan template. ..................................... 415 Figure 22.2 An example control plan—first page. ................................ 416 Figure 22.3 An example control plan—second page. .............................. 417 Table 22.1 Process FMEA and control plan. ..................................... 420 Figure 23.1 The house of lean. ................................................. 434 Table 23.1 Lean Six Sigma tools. .............................................. 435