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Six-Sigma Quality

Six-Sigma Quality. Chapter 9. 9- 2. OBJECTIVES. Total Quality Management Defined Quality Specifications and Costs Six Sigma Quality and Tools External Benchmarking ISO 9000 Service Quality Measurement. 9- 3. Total Quality Management (TQM).

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Six-Sigma Quality

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  1. Six-Sigma Quality Chapter 9

  2. 9-2 OBJECTIVES • Total Quality Management Defined • Quality Specifications and Costs • Six Sigma Quality and Tools • External Benchmarking • ISO 9000 • Service Quality Measurement

  3. 9-3 Total Quality Management (TQM) • Total quality management is defined as managing the entire organization so that it excels on all dimensions of products and services that are important to the customer • Careful design of product or service • Ensuring that the organization’s systems can consistently produce the design • TQM was a response to the Japanese superiority in quality

  4. 9-4 Quality Specifications • Design quality: Inherent value of the product in the marketplace • Dimensions include: Performance, Features, Reliability/Durability, Serviceability, Aesthetics, and Perceived Quality. • Conformance quality: Degree to which the product or service design specifications are met

  5. Three Quality Gurus Define Quality Crosby: conformance to requirements Deming: A predictable degree of uniformity and dependability at low cost and suited to the market Juran: fitness for use (satisfies customer’s needs)

  6. Deming’s 14 Points • Create consistency of purpose • Lead to promote change • Build quality into the products • Build long term relationships • Continuously improve product, quality, and service • Start training • Emphasize leadership

  7. Deming’s 14 Points • Drive out fear • Break down barriers between departments • Stop haranguing workers • Support, help, improve • Remove barriers to pride in work • Institute a vigorous program of education and self-improvement • Put everybody in the company to work on the transformation

  8. Shewhart’s PDCA Model 4.Act 1.Plan Identify the improvement and make a plan Implement the plan 2.Do 3.Check Is the plan working Test the plan

  9. 9-9 Appraisal Costs External Failure Costs Prevention Costs Internal FailureCosts Costs of Quality Costs of Quality

  10. 9-10 Six Sigma Quality • A philosophy and set of methods companies use to eliminate defects in their products and processes • Seeks to reduce variation in the processes that lead to product defects

  11. 9-11 Six Sigma Quality (Continued) • Six Sigma allows managers to readily describe process performance using a common metric: Defects Per Million Opportunities (DPMO)

  12. 9-12 Six Sigma Quality (Continued) So, for every one million letters delivered this city’s postal managers can expect to have 1,000 letters incorrectly sent to the wrong address. Example of Defects Per Million Opportunities (DPMO) calculation. Suppose we observe 200 letters delivered incorrectly to the wrong addresses in a small city during a single day when a total of 200,000 letters were delivered. What is the DPMO in this situation? Cost of Quality: What might that DPMO mean in terms of over-time employment to correct the errors?

  13. 9-13 Six Sigma Quality: DMAIC Cycle • Define, Measure, Analyze, Improve, and Control (DMAIC) • Developed by General Electric as a means of focusing effort on quality using a methodological approach • Overall focus of the methodology is to understand and achieve what the customer wants • A 6-sigma program seeks to reduce the variation in the processes that lead to these defects • DMAIC consists of five steps….

  14. 9-14 Six Sigma Quality: DMAIC Cycle (Continued) 1. Define (D) Customers and their priorities 2. Measure (M) Process and its performance 3. Analyze (A) Causes of defects 4. Improve (I) Remove causes of defects 5. Control (C) Maintain quality

  15. 9-15 Example to illustrate the process… • We are the maker of this cereal. Consumer reports has just published an article that shows that we frequently have less than 16 ounces of cereal in a box. • What should we do?

  16. 9-16 Step 1 - Define • What is the critical-to-quality characteristic? • The CTQ (critical-to-quality) characteristic in this case is the weight of the cereal in the box.

  17. 9-17 2 - Measure • How would we measure to evaluate the extent of the problem? • What are acceptable limits on this measure?

  18. 9-18 2 – Measure (continued) • Let’s assume that the government says that we must be within ± 5 percent of the weight advertised on the box. • Upper Tolerance Limit = 16 + .05(16) = 16.8 ounces • Lower Tolerance Limit = 16 – .05(16) = 15.2 ounces

  19. 9-19 2 – Measure (continued) • We go out and buy 1,000 boxes of cereal and find that they weight an average of 15.875 ounces with a standard deviation of .529 ounces. • What percentage of boxes are outside the tolerance limits?

  20. 9-20 Process Mean = 15.875 Std. Dev. = .529 Upper Tolerance = 16.8 Lower Tolerance = 15.2 What percentage of boxes are defective (i.e. less than 15.2 oz)? Z = (x – Mean)/Std. Dev. = (15.2 – 15.875)/.529 = -1.276 NORMSDIST(Z) = NORMSDIST(-1.276) = .100978 Approximately, 10 percent of the boxes have less than 15.2 Ounces of cereal in them!

  21. 9-21 Step 3 - Analyze - How can we improve the capability of our cereal box filling process? • Decrease Variation • Center Process • Increase Specifications

  22. 9-22 Step 4 – Improve – How good is good enough? Motorola’s “Six Sigma” • 6s minimum from process center to nearest spec

  23. 9-23 Motorola’s “Six Sigma” • Implies 2 ppB “bad” with no process shift. • With 1.5s shift in either direction from center (process will move), implies 3.4 ppm “bad”.

  24. 9-24 Step 5 – Control • Statistical Process Control (SPC) • Use data from the actual process • Estimate distributions • Look at capability - is good quality possible • Statistically monitor the process over time

  25. 9-25 Analytical Tools for Six Sigma and Continuous Improvement: Flow Chart No, Continue… Material Received from Supplier Inspect Material for Defects Defects found? Yes Can be used to find quality problems Return to Supplier for Credit

  26. 9-26 0.58 Diameter 0.56 0.54 0.52 0.5 0.48 0.46 0.44 1 2 3 4 5 6 7 8 9 10 11 12 Time (Hours) Analytical Tools for Six Sigma and Continuous Improvement: Run Chart Can be used to identify when equipment or processes are not behaving according to specifications

  27. 9-27 Analytical Tools for Six Sigma and Continuous Improvement: Pareto Analysis Can be used to find when 80% of the problems may be attributed to 20% of the causes 80% Frequency Design Assy. Instruct. Purch. Training

  28. 9-28 Analytical Tools for Six Sigma and Continuous Improvement: Checksheet Can be used to keep track of defects or used to make sure people collect data in a correct manner Monday • Billing Errors • Wrong Account • Wrong Amount • A/R Errors • Wrong Account • Wrong Amount

  29. 9-29 Analytical Tools for Six Sigma and Continuous Improvement: Histogram Can be used to identify the frequency of quality defect occurrence and display quality performance Number of Lots 0 1 2 3 4 Defectsin lot Data Ranges

  30. 9-30 Machine Man Effect Environment Method Material Analytical Tools for Six Sigma and Continuous Improvement: Cause & Effect Diagram The results or effect Possible causes: Can be used to systematically track backwards to find a possible cause of a quality problem (or effect)

  31. 9-31 UCL 1020 1010 1000 LCL 990 980 970 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Analytical Tools for Six Sigma and Continuous Improvement: Control Charts Can be used to monitor ongoing production process quality and quality conformance to stated standards of quality

  32. 9-32 Six Sigma Roles and Responsibilities • Executive leaders must champion the process of improvement • Corporation-wide training in Six Sigma concepts and tools • Setting stretch objectives for improvement • Continuous reinforcement and rewards

  33. 9-33 The Shingo System: Fail-Safe Design • Shingo’s argument: • SQC methods do not prevent defects • Defects arise when people make errors • Defects can be prevented by providing workers with feedback on errors • Poka-Yoke includes: • Checklists • Special tooling that prevents workers from making errors

  34. 9-34 ISO 9000 and ISO 14000 • Series of standards agreed upon by the International Organization for Standardization (ISO) • Adopted in 1987 • More than 160 countries • A prerequisite for global competition? • ISO 9000 an international reference for quality, ISO 14000 is primarily concerned with environmental management

  35. 9-35 Three Forms of ISO Certification 1. First party: A firm audits itself against ISO 9000 standards 2. Second party: A customer audits its supplier 3. Third party: A "qualified" national or international standards or certifying agency serves as auditor

  36. 9-36 External Benchmarking Steps 1. Identify those processes needing improvement 2. Identify a firm that is the world leader in performing the process 3. Contact the managers of that company and make a personal visit to interview managers and workers 4. Analyze data

  37. 9-37 Question Bowl Approximately what percentage of every sales dollar is allocated to the “cost of quality”? • Less than 5% • About 10% • Between 15 and 20 % • More than 30% • None of the above Answer: c. Between 15 and 20 % (for cost of reworking, scrapping, repeated service, etc.)

  38. 9-38 Question Bowl Which of the following are classifications of the “cost of quality”? • Appraisal costs • Prevention costs • Internal failure costs • External failure costs • All of the above Answer: e. All of the above

  39. 9-39 Question Bowl Which of the following are functions of a quality control department? • Testing product designs for reliability • Gathering product performance data • Planning and budgeting the QC program • All of the above • None of the above Answer: d. All of the above

  40. 9-40 Question Bowl Which of the following is a Critical Customer Requirement (CCR) in the context of a Six Sigma program? • DMAIC • DPMO • PCDA • DOE • None of the above Answer: e. None of the above (The CCR is the criteria that is used to define desired quality. Processing a loan in 10 days is an example of a CCR.)

  41. 9-41 Question Bowl The DMAIC cycle of Six Sigma is similar to which of the following quality management topics? • Continuous improvement • Servqual • ISO 9000 • External benchmarking • None of the above Answer: a. Continuous improvement

  42. 9-42 Question Bowl The “A” in DMAIC stands for which of the following? • Always • Accessibility • Analyze • Act • None of the above Answer: d. Analyze (Define, Measure, Analyze, Improve and Control)

  43. 9-43 Question Bowl Which of the following analytical tools depict trends in quality data over time? • Flowcharts • Run charts • Pareto charts • Checksheets • Cause and effect diagrams Answer: b. Run charts

  44. 9-44 End of Chapter 9

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