Total Quality Management - Overview Session 13 Compiled by Prof. Sanjib Biswas Is your mobile phone worthy to you? Why? Do you recommend it to your mother on the mothers’ day? Why? What else you require? Less price? More features? Gift? Convenience? After sales support? July 9 & 16, 2018 2 • What is “ Quality”? • What is the meaning of “Total”? • What is “Management”? • What is the difference between “ TQC” and “TQM”? • What is the difference between Little ‘Q’ & Big ‘Q’? • What is the difference between “ Best-in-Class” & “ World Class” Quality? July 9 & 16, 2018 3 Quality Customer satisfactions and loyalty (or fitness for use) as defined by Dr Joseph M.Juran Predictable degree of uniformity as defined by Dr Deming. Loss to society as defined by Taguchi Conformation to specifications as defined by Crosby International Organisation for Standardization (ISO) defines quality as the “Totality of Characteristics of an entity that bear on its ability to satisfy stated and implied needs”. In the context of today’s business, quality is best defined as “customer satisfaction and loyalty”. July 9 & 16, 2018 4 TQM – Key Aspects • Customer is the dominant resource. • Profits follow Quality and not the other way round. • View that Quality is composed of multi-dimensional attributes. • Stresses on quality, flexibility & service to create value for customers. • Multiskilling. • Flat organization structure. • Process oriented approach. July 9 & 16, 2018 5 TQC or TQM? • Generally total quality control relates to the specific act of checking that a product (for example) is coming off the production line to the expected tolerances and having processes to correct the manufacturing if something is not right. • Total quality management generally encompasses the quality of all business processes ensuring that the company does everything as efficiently as possible. July 9 & 16, 2018 6 Little ‘Q’ vs Big ‘Q’ Fig: Attractive/Charming Quality of Prof. Kano July 9 & 16, 2018 7 Best-in-class vs World-class • Customers’ expectations of quality are not the same for different classes of products or services. • Best-in-class quality means being the best product or service in a particular class of products or services. • Being a world-class company means that each of its products and services are considered best-in-class by its customers. July 9 & 16, 2018 8 Revenue lost through poor quality $10,000,00 0 1,000 X 25% 250 X 75% 188 X $10,000 $1,880,000 Annual customer service revenue Number of customers Percent dissatisfied Number of dissatisfied Percent of switchers (60-90% of dissatisfied) Hidden Cost of Poor Quality: Lost sales, Extra inventory, Downtime, Loss of goodwill, excess paperwork, delay, Low morale etc. Number of switchers Average revenue per customer “ Good Quality is Cheap” Revenue lost through poor quality Source : The University of Tampa (1990) July 9 & 16, 2018 9 Expectations July 9 & 16, 2018 10 Enterprise Quality Enterprise Quality = meeting the needs and expectations of all interested parties in a balanced way over the long term. Phases: Decide Prepare Launch Expand Sustain “ I believe the distinction between a good company and a great one is this; A good company delivers excellent products and services; A great one delivers excellent products and services and strives to make the world a better place” - William Clay Ford Jr July 9 & 16, 2018 11 Using the Road Map Maximizes the Probability of Success and Avoids the “Flavour of the Month” syndrome Phase 5 • Integrate, Audit, Measure, Assess, Review, Inspect, Focus Phase 4 Phase 3 • Expand Training across the organisation • Transition Training from Juran to Client • Initial Training • Pilot Projects Phase 2 • Up Front Planning • Establish Infrastructure • Executive Onboard Phase 1 Yes to Deployment Organisation / Partner July 9 & 16, 2018 Time 12 Significant contributions by the Quality Gurus July 9 & 16, 2018 13 Historic Milestones of TQM ( selected) July 9 & 16, 2018 14 Evolution of Modern Quality concept Source: “From Product Quality to Organization Quality” by Dr. Isaac Sheps July 9 & 16, 2018 15 Deming’s 14 points • Create constancy of purpose for improvement of product and service. • Adopt the new philosophy. • Cease dependence on mass inspection. • End the practice of awarding business on the price tag alone. • Improve constantly and forever the system of production and training. • Institute training. • Institute leadership. • Drive out fear. • Break down barriers between staff areas. • Eliminate slogans, exhortations, and targets for the workforce. • Eliminate numerical quotas. • Remove barriers to pride in workmanship. • Institute a vigorous program of education and retraining. • Take action to accomplish the program. July 9 & 16, 2018 16 What is the Plan Do Check Act (PDCA) Method? PDCA: – is a Scientific Method to solving problems – requires facts, measurement, objective analysis and critical thinking surrounding the problem – requires data and numerical evidence of the problem – is designed to be applied over and over again, not just one time • referred to as “Closed Loop Thinking” – naturally increases knowledge of the individual(s) evaluating the causes of a problem “As long as the circle is rolling, the quality is providing. Once the circle is interrupted the quality fails.” (Deming) July 9 & 16, 2018 17 Standards, Process Improvement and the PDCA Method The Current Standard serves as “The Chock” to PREVENT BACKSLIDING” Constant Consistent & Continuous Change for the Better A PROCESS If we DON’T continuously improve we will experience a NATURALLY occurring Reaction! “CHAOS” WILL TAKE OVER > STANDARDS WILL BACKSLIDE July 9 & 16, 2018 18 “A3” Proposal/Report Format PLAN PLAN An A3 lays out an entire plan, large or small, on one sheet of paper. It should be visual and extremely concise. PlanleftIt should tell a story, laidImplementation out from upper hand side to lower right, which anyone can understand.PLAN PLAN Do PLAN Check July 9 & 16, 2018 19 Applying PDCA and One Page Report Writing Exercise instructions: July 9 & 16, 2018 1. Break into teams 2. Each team pick a topic from work or from school 3. For each topic, work through as much of the A-3 format as you can. Defining the business problem is a good place to start. 4. Use visuals if possible. Use 5 why analysis to understand root cause. Note where you are making assumptions vs using facts. 5. Brainstorm recommendations that address root cause. 6. Summarize your ideas in the A-3 format. 20 Quality Objectives What are your organization’s quality objectives? • • • • • • • • Customer Satisfaction? Time to market? On-Time Delivery? Cost Savings? ROI? Productivity? Performance? Cycle time? How fast does your organization want to improve? How important is your budget and cost savings? July 9 & 16, 2018 21 Juran’s Definition of Quality “Fitness for Use” Product Features that Meet Customer Needs Freedom from Deficiencies • Provide customer satisfaction • Eliminate defects, errors, & waste • Create product salability • Compete for market share • Respond to customer needs • Higher quality costs more July 9 & 16, 2018 • Avoid product dissatisfaction • Effect is on costs • Higher quality costs less 22 Juran’s Trilogy July 9 & 16, 2018 23 The Five Erroneous Assumptions • Quality means goodness, elegance • Quality is intangible, not measurable • The “economics of quality” are prohibitive, not relevant • Quality problems originate with the workers • Quality is the responsibility of the quality department • Quality is conformance to requirements • Quality is measured by the cost of nonconformance • It is cheaper to do things right the first time • Most problems start in planning and development • Quality is shared by every function and department “Quality is Free” since a quality program can save a company more money than it costs to implement Source: “ Quality is Free” – Philip Crosby (1979) July 9 & 16, 2018 24 Cost of Poor Quality (CoQ) Represents the difference between The actual cost of production or service & What the cost would be if the process were effective in manufacturing products that • met customer needs and • were defect free. “In most companies the costs of poor quality run at 20 to 40 percent... In other words, about 20 to 40 percent of the companies’ efforts are spent in redoing things that went wrong because of poor quality” (Juran on Planning for Quality, 1988) July 9 & 16, 2018 25 Total Quality Cost I want my money back! Prevention Internal Failure Appraisal External Failure $ Cost of Quality (COQ) July 9 & 16, 2018 26 Generic CoQ models and cost categories July 9 & 16, 2018 27 CoQ Metrics July 9 & 16, 2018 28 Example of CoQ Calculation Scrap/Waste July 9 & 16, 2018 29 Example of CoQ Calculation Customer Returns July 9 & 16, 2018 30 Example of CoQ Calculation Rework Downtime July 9 & 16, 2018 31 Example of CoQ Calculation: Investigation Time Disposal Cost July 9 & 16, 2018 32 Relating COQ to Business Measures: Example Return on Asset = Profit Margin X Asset Turnover ( Dupont Financial Model) Illustrative Example: Suppose, COQ was 10% of Sales revenue. Profit margin was 7% & Asset turnover was 3%. Now, after implementing a quality improvement effort organization wide, the COQ becomes 6% now whereas asset turnover remains the same. What will be the impact on Return on Asset ? Since COQ directly reduces the cost, it will influence the profit margin. Reduction in COQ is (10-6) = 4% => New profit Margin will be (7+4) = 11%. Thus, new Return on Asset will be (11* 3) = 33% which is much higher as compared to the earlier one i.e. (7* 3) = 21%. July 9 & 16, 2018 33 TQM : Up-stream Quality in Purchasing Process Manufacturer Stages of Progress Production Incoming Inspection Supplier Outgoing Inspection Production Additional Cost Passed to the Customer ($) 1 2 3 4 5 6 Poka-Yoke / Process Control Note: Circles indicate the importance of quality check-points for the material produced by suppliers Source : Techniques of continous improvement – Prof. Kiyoshi Suzaki July 9 & 16, 2018 34 The components of organizational excellence Business Excellence is “excellence” in strategies, business practices, and stakeholder-related performance results that have been validated by assessments using proven business excellence models. Source: Assessing Business Excellence - L. J. Porter & S. J. Tanner (2Ed., Elsevier ButterworthHeinemann, 2004) 11 March 2023 Sanjib Biswas 35 The Excellence Maturity Model Source: Assessing Business Excellence - L. J. Porter & S. J. Tanner (2Ed., Elsevier Butterworth-Heinemann, 2004) 11 March 2023 Sanjib Biswas 36 TQM Model (For examining the impact of business excellence practices in diverse organizations) Source: GAO (1991) 11 March 2023 Sanjib Biswas 37 TQM Business Excellence Models Widely used models/frameworks: oDeming Prize oMalcolm Baldrige National Quality Award (MBNQA) oEuropean Foundation for Quality Management (EFQM) oPhilips Quality Award (PQA) oMotorola Business Excellence Model oAustralian Business Excellence Framework (ABEF) oTata Business Excellence Model (TBEM) oGolden Peacock National Quality Award oCII-EXIM Model etc. 11 March 2023 Sanjib Biswas 39 Deming Prize It was set up in 1952 by the Japanese Union of Scientists and Engineers (JUSE) to recognize and encourage companies that do an outstanding work in the field of Quality Management. It is the oldest and the most prestigious Quality Award in the world. In comparison the MBNQA, USA was set up in 1987 and EFQM, Europe was set up in 1992. Amongst these three, Deming Prize is the only one that can be challenged by a company from any country. 11 March 2023 Sanjib Biswas Criteria 40 Malcolm Baldrige Performance Excellence Framework 11 March 2023 Sanjib Biswas 41 EFQM Excellence Model 11 March 2023 Sanjib Biswas 42 ISO 9000 Series • ISO 9000 (a guide) • ISO 9001 (a set of requirements for the quality system of the supplier) • ISO 9002 (product standards) • ISO 9003 (final inspection and testing) • ISO 9004 (guidelines for developing and implementing quality system principles, structure, auditing and review) ISO 9000 Standards • The implementation of the ISO 9000 standards does not imply necessarily a higher level of quality but it forces a company to assure its customers that the products are manufactured according to the standards. • The directives of standards cover mainly such areas as product safety, and other quality considerations. • The list of products (medical implants, gas appliances, toys, building products, etc) PROCESS : Nonconformance Print Offset Types of Defect Date No of nonconformances Date Date Date Date 1-Mar 2-Mar Dent IIII III Burr III Date IIII Total defects IIII No of Defects 3-Mar 4-Mar 5-Mar 6-Mar Doc No : PV/TF1/PDN /FM/ XXX Rev No : 00 PV TECHNOLOGIES INDIA LIMITED PRODUCTION CHECKSHEET FOR GLASS SEAMING & INSPECTION Rev Date : DD / MM / YYYY Date : S.No Parameter Unit 1 DI water inlet pressure bar 2 CDA Pressure 3 Seaming belt condition 4 Rubber roller 5 Nozzle condition Shift Technician Shift Incharge bar A 7 9 B 11 13 15 17 C 19 21 23 1 3 5 SNO CLASS BOUNDARY MID POINT FREQUENCY TOTAL 1. 7.10 - 7.79 7.45 IIII 4 2. 7.80 – 8.49 8.15 IIII 5 3. 8.50 – 8.85 IIII IIII 10 4. 9.20 - 9.55 IIII IIII IIII IIII 5. 9.90 – 10.59 10.25 IIII IIII I 11 6. 10.60 – 11.29 10.95 IIII 5 7. 11.30 – 11.99 11.65 IIII I 6 9.19 9.89 III 23 25 Frequency 20 15 10 5 0 7.1~7.79 7.8~8.49 8.5~9.19 9.2~9.89 Thickness 9.9~10.59 10.6~11.29 11.3~11.99 Bell Shape A special type of symmetric unimodal histogram is one that is bell shaped: Symmetry A histogram is said to be symmetric if, when we draw a vertical line down the center of the histogram, the two sides are identical in shape and size: Skewed Distribution A skewed histogram is one with a long tail extending to either the right or the left: • What is a Pareto? • A data display tool that breaks down discrete observations into separate categories for the purpose of identifying the “vital few”. • Discovered by Vilfredo Pareto (1906) • Why use it? • To focus on the problems/issues that offer greatest potential for improvement • Identify “the vital few” Identify the relative importance of problems and see them in a simple graphical way • Prioritize our efforts and resources for improvements • Where to use it? • Where we would want to identify • Cause or source of the problem • Customer type • Location (region, building) Category Number Halm unit 1015 FP1 860 3M camera syatem 610 Rotary table 485 FSCC 300 RSCC 75 Cases 55 FP2 /3 30 Pointer 30 % 29 25 18 14 9 2 2 1 1 Cum% 29 54 72 86 95 97 98 99 100 100 90 80 70 60 50 40 30 20 10 0 1100 1000 900 800 700 600 500 400 300 200 100 0 Halm unit FP1 3M Rotary camera table syatem Category FSCC RSCC Cases Cumulative% Numbers of Occurence Pareto Chart of GBP CS downtime Start Alarm Rings Ready to get up Climb out of bed End Delay Hit Snooze Button Fish-Bone diagram is a structured approach to exhaustively determine perceived sources (causes) of a problem (effect) Also known as Ishikawa Diagram or cause & effect diagram. • Why use it? • To help the team organize and graphically display all the knowledge it has about the problem • What does it do? • It helps unearth all possible causes for the problem at hand by capturing views of all members • Creates a consensus around the problem and builds support for resulting solutions • Focuses the team on causes rather than symptoms • Organizing data serves as a guide for discussion and inspires more ideas Deposition Power Vs Film Uniformity Film Uniformity(%) 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 Deposition Power(KW) Deposition Power Vs Film Uniformity Film Uniformity(%) 30 25 20 15 10 5 0 15 20 25 Deposition Power(KW) 30 35 Deposition Power(KW) 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5 15 Film Uniformity(%) 40 28 20 35 18 24 20 28 14 30 18 25 35 26 17 27 20 28 21 32 16 28 14 35 30 19 24 Deposition Power(KW) 16 16.5 17 17.5 18 18.5 19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30 Film Uniformity(%) 22 24 20 21 20 21 18 20 19 17 18 16 19 16 17 16 15 17 14 15 16 14 15 11 14 12 11 13 10 Film Uniformity(%) Deposition Power Vs Film Uniformity 60 50 40 30 20 10 0 25 30 35 40 45 50 Deposition Power(KW) Film Uniformity(%) Deposition Power Vs Film Uniformity 35 30 25 20 15 10 5 0 10 15 20 25 30 35 Deposition Power(KW) 40 45 Deposition Power(KW) 30 30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40 40.5 41 41.5 42 42.5 43 43.5 44 44.5 45 Film Uniformity(%) 10 13 14 12 14 15 13 14 16 15 14 20 18 19 17 24 19 21 25 24 30 28 26 27 29 33 34 31 36 44 50 De posi ti on Powe r( KW) 14 14.5 15 16 16.5 17 17.5 18 18.5 19 19.5 20 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 Fi l m Uni formi ty( %) 30 20 24 22 24 20 21 20 21 18 20 19 19 17 18 16 19 16 17 16 15 17 14 15 16 14 15 11 14 12 11 13 10 13 14 12 14 15 13 14 16 15 14 20 18 19 17 24 19 21 25 Team members Grievance handling Appraisal system Canteen Transport US 2 2 1 1 NG 1 3 1 1 DS 1 2 2 1 NB 3 1 1 1 PK 1 2 2 1 Total 8 10 7 5 P Process 3 S I Suppliers Inputs 1 2 5 4 Process Boundary O C Outputs Customers 5 – WHY ANALYSIS The 5-Why analysis method is used to move past symptoms and understand the true root cause of a problem. It is said that only by asking "Why?" five times, successively, you can delve into a problem deeply enough to understand the ultimate root cause. Problem 1st Why 2nd Why 3rd Why Rotary table throw ing aw ay the Cells Rotary Table throw ing aw ay Cells from Som e heads Cell is falling dow n from head no. 1&7 during rotation of Rotary table Less Vacuum level to hold the cell on the head no 1 & 7 of Rotary table 4th Why 5th Why Vacuum leakage in the supply of head no 1&7 Vacuum seal found dam aged in head no 1 & 7 BACK BACK 79 What is a Process ? Sequence of interdependent and linked procedures which, at every stage, consume one or more resources (employee time, energy, machines, money) to convert inputs (data, material, parts, etc.) into outputs. These outputs then serve as inputs for the next stage until a known goal or end result is reached. 80 11 March 2023 DISTRIBUTION While individual measured values may all be different, as a group they tend to exhibit a pattern. This is called distribution which can be described by: 81 11 March 2023 Location (Process level or centering) Spread or dispersion (Range of values from smallest to largest) Shape (Pattern of variation, whether symmetrical or skewed etc.) Distribution of Data 82 Normal distributions 11 March 2023 Skewed distribution Variation 83 There is no two natural items in any category are the same. Variation may be quite large or very small. If variation very small, it may appear that items are identical, but precision instruments will show differences. 11 March 2023 3 Categories of variation 84 Within-piece variation ◦ One portion of surface is rougher than another portion. Apiece-to-piece variation ◦ Variation among pieces produced at the same time. Time-to-time variation ◦ Service given early would be different from that given later in the day. 11 March 2023 Source of variation 85 Equipment ◦ Tool wear, machine vibration, … Material ◦ Raw material quality Environment ◦ Temperature, pressure, humadity Operator ◦ Operator performs- physical & emotional 11 March 2023 A Spread A - Original Process B - Increase in spread with same location B Change in process variation B – Pattern is skewed Shape A - Original symmetrical pattern Change in pattern of variation 86 11 March 2023 In the figure Change in pattern of variation the Original pattern (A) is symmetrical but the new pattern (B) is skewed. Even though the centering is the same, the shapes or patterns are different. 87 11 March 2023 STABILITY If the process characterised by distribution remains unchanged over a period of time, then the process is said to be Stable and Repeatable. This can be understood from the following depiction of process over a period of time, see the figure below: Target Time Stable and repeatable process This pattern results when only common causes are present in the process. 88 11 March 2023 Level PPM % *(Yield) 6 3.4 99.99966 5 233 99.9767 4 6220 99.379 3 66820 93.32 2 308700 69.13 1 697700 60.23 Type of Data Continuous Attribute Control Chart - Individual measurement - X - R, X-s charts - p, c, u charts - Individual measurement The common causes are minute and many and are individually not measurable. The pattern resulting from the influence of common causes is called “State of statistical control” or sometimes, just “In control”. It is called statistical because the variation can be described by statistical laws. It only common causes are present and do not change, the output of a process is predictable. They are known to be “Chance Causes” 9 The advantages of maintaining a state of statistical control are: However, process level and variation may change due to influence of causes additional to common causes. Such causes are called special causes. 9 Examples of special causes are changes in setting, operator, material input, etc. When they occur, they make the (overall) process distribution change. Unless they are arrested, they will continue to affect the process output in unpredictable ways as shown below: Increase in variation Shift in process level Time Original process 9 Shift in process level and variation Unstable Process They are also called “assignable causes” Changes in process pattern due to special causes can be either detrimental or beneficial. When detrimental, they need to be identified and eliminated. When beneficial, they need to be perpetuated by making them a permanent part of the process. 9 11 March Date Present employee • • 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 2030 2020 2010 2000 1990 1980 1970 1960 1950 1 Nos Trend Chart for Present employee Variable vs. Attribute 104 Control Charts show sample data plotted on a graph with CL, UCL, and LCL Control chart for variables are used to monitor characteristics that can be measured, e.g. length, weight, diameter, time Control charts for attributes are used to monitor characteristics that have discrete values and can be counted, e.g. % defective, number of flaws in a shirt, number of broken eggs in a box 11 March 2023 Types of Control Charts 105 X-bar-R: Continuous values measuring product or service attributes X: similar, but subgroups contain one value Nonconforming Units (based on the Binomial distribution): p chart, np chart. Nonconformities (based on the Poisson distribution): c chart, u chart. Special Control Charts: Cusum, Trend, Moving average, Multivariate etc. 11 March 2023 Control Chart Selection Quality Characteristic Variable Attribute Defective n>1? no x and MR yes no n>=10? Defect x and R constant sample size? yes no yes x and s 106 11 March 2023 p-chart with variable sample size constant sampling unit? p or np yes no c u Control Charts for Variables 107 Use X-bar and R-bar charts together Used to monitor different variables X-bar & R-bar Charts reveal different problems In statistical control on one chart, out of control on the other chart? OK? 11 March 2023 Control Charts for Variables Use X-bar charts to monitor the changes in the mean of a process (central tendencies) Use R-bar charts to monitor the dispersion or variability of the process System can show acceptable central tendencies but unacceptable variability or System can show acceptable variability but unacceptable central tendencies 108 11 March 2023 Constructing a X-bar Chart: A quality control inspector at the Cocoa Fizz soft drink company has taken three samples with four observations each of the volume of bottles filled. If the standard deviation of the bottling operation is .2 ounces, use the below data to develop control charts with limits of 3 standard deviations for the 16 oz. bottling operation. Time 1 Time 2 Time 3 Observation 1 15.8 16.1 16.0 Observation 2 16.0 16.0 15.9 Observation 3 15.8 15.8 15.9 Observation 4 15.9 15.9 15.8 Sample means (X-bar) 15.875 15.975 15.9 0.2 0.3 0.2 Sample ranges (R) 109 11 March 2023 Center line and control limit formulas x 1 x 2 ...x n σ , σx k n where (k ) is the # of sample means and (n) x is the # of observations w/in each sample UCL x x zσ x LCL x x zσ x Solution and Control Chart (X-bar) Center line (X-double bar): 15.875 15.975 15.9 x 15.92 3 Control limits for±3σ limits: .2 UCL x x zσ x 15.92 3 16.22 4 .2 LCL x x zσ x 15.92 3 15.62 4 110 11 March 2023 X-Bar Control Chart 111 11 March 2023 Control Chart for Range (R) Center Line and Control Limit formulas: R 0.2 0.3 0.2 .233 3 UCLR D4 R 2.28(.233) .53 LCLR D3 R 0.0(.233) 0.0 112 11 March 2023 Factors for three sigma control limits Factor for x-Chart Sample Size (n) 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A2 1.88 1.02 0.73 0.58 0.48 0.42 0.37 0.34 0.31 0.29 0.27 0.25 0.24 0.22 Factors for R-Chart D3 0.00 0.00 0.00 0.00 0.00 0.08 0.14 0.18 0.22 0.26 0.28 0.31 0.33 0.35 D4 3.27 2.57 2.28 2.11 2.00 1.92 1.86 1.82 1.78 1.74 1.72 1.69 1.67 1.65 R-Bar Control Chart 113 11 March 2023 Second Method for the X-bar Chart Using R-bar and the A2 Factor Use this method when sigma for the process distribution is not know Control limits solution: 0.2 0.3 0.2 R .233 3 UCL x X A 2 R 15.92 0.73.233 16.09 LCLx X A 2 R 15.92 0.73.233 15.75 114 11 March 2023 Another Example A pharmaceutical Mfg. needs to control the concentration of active ingredient in a formula used to restore hair to bald people. The concentration should be around 10%. Accordingly, in a shift, total 30 observations taken from 3 different lots are as follow: 10.22, 10.46, 10.82, 9.88, 9.92, 10.15, 10.69, 10.12, 10.31, 10.07, 10.25, 10.06, 10.52, 10.31, 9.94, 10.85, 10.32, 10.8, 10.23, 10.15, 10.37, 10.59, 10.13, 10.33, 9.39, 10.14, 9.79, 10.26, 10.2, 10.31. Comment on the stability of the process. 115 11 March 2023 Control Charts for Attributes –p-Charts & c-Charts Attributes are discrete events; yes/no, pass/fail ◦ Use p-Charts for quality characteristics that are discrete and involve yes/no or good/bad decisions Number of leaking caulking tubes in a box of 48 Number of broken eggs in a carton ◦ Use c-Charts for discrete defects when there can be more than one defect per unit Number of flaws or stains in a carpet sample cut from a production run Number of complaints per customer at a hotel 116 11 March 2023 Defect vs. Defective 117 ‘Defect’ – a single nonconforming quality characteristic. ‘Defective’ – items having one or more defects. 11 March 2023 P-Chart 118 The P Chart is used for data that consist of the proportion of the number of occurrences of an event to the total number of occurrences. It is used in quality to report the fraction or percent nonconforming in a product, quality characteristic, or group of quality characteristics. 11 March 2023 P-Chart Formula: 119 11 March 2023 p np n The fraction nonconforming, p, is usually small, say, 0.10 or less. Because the fraction nonconforming is very small, the subgroup sizes must be quite large to produce a meaningful chart. Formula p np n UCL p 3 LCL p 3 120 11 March 2023 p (1 p ) n p (1 p ) n p-Chart Example: A Production manager for a tire company has inspected the number of defective tires in five random samples with 20 tires in each sample. The table below shows the number of defective tires in each sample of 20 tires. Calculate the control limits. 121 Sample Number of Defective Tires Number of Tires in each Sample Proportion Defective 1 3 20 .15 2 2 20 .10 3 1 20 .05 4 2 20 .10 5 2 20 .05 Total 9 100 .09 11 March 2023 CL p σp Solution: # Defectives 9 .09 Total Inspected 100 p(1 p ) (.09)(.91) 0.64 n 20 UCLp p z σ .09 3(.064) .282 LCLp p z σ .09 3(.064) .102 0 p- Control Chart 122 11 March 2023 Another Example One French Tire Mfg. company randomly samples 40 tires at the end of each shift to test for tires that are defective. The number of defectives in 12 shifts is as follows: 4,2, 0, 5, 2, 3, 14, 2, 3, 4, 12, 3. Construct a control chart for this process. Is the production process under control? 123 11 March 2023 Control Charts for Count of Nonconformities 124 11 March 2023 The nonconformities chart controls the count of nonconformities within the product or service. An item is classified as a nonconforming unit whether it has one or many nonconformities. Count of nonconformities (c) chart. Count of nonconformities per unit (u) chart. Control Charts for Count of Nonconformities 125 11 March 2023 Since these charts are based on the Poisson distribution, two conditions must be met: 1. The average count of nonconformities must be much less than the total possible count of nonconformities. 2. The occurrences are independent. Formula c c g UCL c 3 c LCL c 3 c 126 11 March 2023 c-Chart Example: The number of weekly customer complaints are monitored in a large hotel using a c-chart. Develop three sigma control limits using the data table below. 127 Week Number of Complaints 1 3 2 2 3 3 4 1 5 3 6 3 7 2 8 1 9 3 10 1 Total 22 11 March 2023 Solution: # complaints 22 CL 2.2 # of samples 10 UCLc c z c 2.2 3 2.2 6.65 LCLc c z c 2.2 3 2.2 2.25 0 c - Control Chart 128 11 March 2023 Another Example The following data are the number of nonconformities in bolts for use in cars made by the Ford Motor Company: 9, 15, 11, 8, 17, 11, 5, 11, 13, 7, 10, 12, 4, 3, 7, 2, 3, 3, 6, 2, 7, 9, 1, 5, 8. Is there evidence that the process is out of control? 129 11 March 2023 Summary 130 11 March 2023 The Cusum Control Chart for Monitoring the Process Mean • The cusum chart incorporates all information in the sequence of sample values by plotting the cumulative sums of the deviations of the sample values from a target value. • If 0 is the target for the process mean, is the average of the jth sample, then the cumulative xj sum control chart is formed by plotting the quantity i Example: Say target 0 = 10 If the process remains in-control, Ci remains near 0 131 11 March 2023 Ci ( x j 0 ) j1 MA Control Chart (Non-Shewhart Control Chart) Plot sample statistic: average of last w data points (Mi ) Computing point to plot ( Mi ) for the chart: xi xi 1 ... xi w1 Mi w Estimate for μ (to find center line): 1 n μ0 xi n i 1 Estimate for (to find control limits, changes with each point): σ 132 3/11/2023 σx w MA Control Chart (Non-Shewhart Control Chart) General model for MA control chart UCL μ0 Lσ μ0 L σx w 1 n CL μ0 xi n i 1 UCL μ0 Lσ μ0 L σx w Notes: ◦ Picking w larger makes chart faster to detect to smaller shifts ◦ Picking w smaller makes chart more sensitive to larger shifts ◦ MA is better at detecting smaller shifts than a Shewhart chart, but not as effective as a EWMA or CUSUM chart 133 3/11/2023 Patterns in Control Charts Upper control limit Target Lower control limit Normal behavior. Process is “in control.” 134 11 March 2023 Patterns in Control Charts Upper control limit Target Lower control limit One plot out above (or below). Investigate for cause. Process is “out of control.” 135 11 March 2023 Patterns in Control Charts Upper control limit Target Lower control limit Trends in either direction, 5 plots. Investigate for cause of progressive change. 136 11 March 2023 Patterns in Control Charts Upper control limit Target Lower control limit Two plots very near lower (or upper) control. Investigate for cause. 137 11 March 2023 Patterns in Control Charts Upper control limit Target Lower control limit Run of 5 above (or below) central line. Investigate for cause. 138 11 March 2023 Patterns in Control Charts Upper control limit Target Lower control limit Erratic behavior. Investigate. 139 11 March 2023 Control Limits and Errors Type I error: Probability of searching for a cause when none exists (a) Three-sigma limits UCL Process average LCL 140 11 March 2023 Control Limits and Errors Type I error: Probability of searching for a cause when none exists (b) Two-sigma limits UCL Process average LCL 141 11 March 2023 Control Limits and Errors (a) Three-sigma limits Type II error: Probability of concluding that nothing has changed UCL Shift in process average Process average LCL 142 11 March 2023 Control Limits and Errors (b) Two-sigma limits Type II error: Probability of concluding that nothing has changed UCL Shift in process average Process average LCL 143 11 March 2023 PROCESS CONTROL This is the state where only common causes are present. The proof of this situation is when the pattern of variation conforms to the statistical normal distribution. It involves continuous monitoring of the process for special causes and eliminating them. Evidence of special causes is provided by systematic patterns in process variability. 144 11 March 2023 Statistical Process Control SPC (Statistical Process Control) is a group of tools and techniques used to determine the stability and predictability of a process. Graphical depictions of process output are plotted on Control Charts. The first Control Charts were developed by Walter Shewhart at Bell Labs in the 1920’s. At this time, telephone technology was in its infancy with poor reliability. Shewhart used SPC to study variation and reduce special causes of failure. Quality and reliability in phone service increased dramatically as a result of SPC. W. Edwards Deming is credited for introducing SPC to the Japanese after World War II. The resulting rise in Japanese quality and reliability is well documented. 145 11 March 2023 Implementation of SPC: An Example 146 11 March 2023 Cpk| 1.0 Background Control Charts show sample data plotted on a graph with CL, UCL, and LCL Cpk| 2.0 Terminologies • Definition: “ Process Capability is the measured, inherent variation of the product turned out by a process” • What is Process: To some unique combination of machines, tools, methods, materials & people engaged in production. • Capability: An ability, based on tested performance, to achieve measurable results • Process Capability = +3σ or -3σ ( a total of 6σ) Where, σ shows the standard deviation of Process under a state of statistical control. • Cp: process capability index • Cpk: minimum process capability index • Pp: process performance index • Ppk: minimum process performance index Cont.. Cpk| 2.0 Terminologies Cpk is: • Process Capability measure • Simple statistical measure estimate level process output which will within specified limit • Provides comparison between output of process Vs Process Specification • Process Improvement: Statistical Process Control tool monitors process tells whether capable or not meeting desired level of performance action to be taken To investigate concerns Helps in process improvement and to achieve desired capability levels Cont.. Cpk| 2.0 Terminologies Cp, Cpk Vs Pp, Ppk Cp Cpk Process Capability Pp Ppk Process Performance Aims Process Verification Cp- Potential Capability What process can do under certain condition i.e. variation in short run for process in state of statistical control Cpk- Actual Capability Estimate of capability what process is doing over extended period of time -Usage process Sigma for -For Process Performance -Process in too new (At development stage) - No historical Data - Sample size is larger from process - Usage sample sigma for calculation - Cpk > Ppk - Anomalies in case of: sample size is small or data represents Cont.. short amount of time only in Cpk 3.0 Relationship between Process variability and Specification width • Three possible ranges for Cp – Cp = 1, as in Fig. (a), process variability just meets specifications – Cp ≤ 1, as in Fig. (b), process not capable of producing within specifications – Cp ≥ 1, as in Fig. (c), process exceeds minimal specifications • One shortcoming, Cp assumes that the process is centered on the specification range • Cp=Cpk when process is centered Cpk| 4.0 Calculations USL: upper specification limit; LSL: lower specification limit; 𝑪𝒑𝒌 = 𝑻𝒐𝒕𝒂𝒍 𝑻𝒐𝒍𝒆𝒓𝒂𝒏𝒄𝒆 𝑷𝒓𝒐𝒄𝒆𝒔𝒔 𝑺𝒑𝒓𝒆𝒂𝒅 Mean: grand average of all the data Sigma hat: estimated inherent variability (noise) of a stable process SD: overall variability Cpk| 4.0 Calculation Process Capability analysis Process: - Take representative sample of process output - Statistical analysis of samples (Mathematical tools, Scattered Plot, Pareto Chart, Histogram, (Minitab/Excel/QI Macros for exel) - Calculate mean and Standard Deviation form the sample size - Calculate Cp Value as well as Cpkl and Cpku - Minimum value from Cpkl and Cpku is the value of Cpk - By observing results of statistical analysis one can be explain or determine future expected process capabilities (ex. In response to Productivity or Quality Attribute) - Process Capability provides a single number which has ability to provide details of process consistency output. Requirement: - Stable Process Cpk| 5.0 Interpretation of Values Sigm a Leve l Defect Rate (DPMO) Yield %Goods Cpk Sigm a Level Defect Rate (DPMO) Yield %Goods Cpk 1σ 691462 30.9 0.33 4σ 6210 99.40% 1.33 2σ 308770 69.10% 0.67 5σ 233 99.98% 1.67 Cpk| 6.0 Cpk Value Ranges Red (Bad) Yellow (OK) Green (Good) Cp Cpk Pp Ppk Sigma < 1.00 < 1.00 < 1.33 < 1.33 < 4.5 1.00 - 1.33 1.00 - 1.33 1.33 - 1.67 1.33 - 1.67 4.5 - 5.5 > 1.33 > 1.33 > 1.67 > 1.67 > 5.5 Cpk| 7.0 What if process not capable -Initial action - increase the inspection level and ensure that confidence with respect to the quality of output product is increased. -Clearly, quality cannot be inspected into a product or process, therefore, the net steps will be to look at how to improve the capability of the process. -Reviewing the product specifications, as by widening the specifications, the capability can be increased. (This can only be performed, if any proposed specification changes are acceptable per customer needs.) -Then looking at the process/Actual Operations itself, there will be a need to identify the sources of variation Measurement, Mother Nature) (Ex. Fish Bone i.e. 6M_Man, Material, Machine, Method, Project Title Business Case Currently the breakage at Last section of Cell Line (Laser to Shrink Wrap) is approx. 5%, which is leading to major line Yield loss & is a major hurdle in achieving the ABP of MBPV because the target of line yield to achieve the ABP is 94%. Metric Breakage % at Laser to Shrink wrap section Goal statement Current Goal / level Target 5% With in 2.5% Target date 28.02.09 Project plan Phase Define Measure Analyze Improve Control Start 27.09.08 25.10.08 16.11.08 11.12.08 01.01.09 End 25.10.08 15.11.08 10.12.08 31.12.08 25.03.09 Opportunity Statement Pain: Cells are breaking at final stage of classification, which is a loss of finished good costing 7.23$ per cell & the amount of loss is 5% of input qty. Impact of pain in Rs. (or soft) : 11.7 Crore/year Sigma Level: 3.1 Project scope Process under improvement: Laser ,Cell Sorting & Shrink Wrapping Starts with: Cell entering in the Laser Ends with: FG Handover to stores Team Selection Remarks Champion: BB : Member: (Maintenance) Member: (Production) Member: ( Production) Member: ( Production) Member: ( Production) Service Quality Customers also form perceptions of quality during the service transaction - how effectively and efficiently the service was delivered and the speed and convenience of completing the transaction . Finally, customers evaluate support activities that occur after the transaction, that is post-sale services. 3-163 Qualities of services Search qualities Experience qualities Credence qualities 11-Mar-23 164 The Service Profit Chain Internal Service Delivery -Employees Employee Value -- Workplace design -- Process Tools -- Rewards/Recognition Service Concept External --Customers Service Value -- Higher reliability -- Lower costs Service Value Outcomes – C/S, Loyalty --- Lifetime Value --- Retention --- Referrals Adapted from Heskett, Sasser, and Schlesinger (1997). 11-Mar-23 Profits Growth 165 Service Quality Gap Model Service Quality Gap Model Customer Customer Perceptions Managing the Evidence Customer Satisfaction GAP 5 Customer / Marketing Research GAP 1 Communication GAP 4 Understanding the Customer Management Perceptions of Customer Expectations Service Delivery Conformance GAP 3 Design GAP 2 Conformance Service Standards 11-Mar-23 Expectations Service Design 166 Service Process Control 11-Mar-23 167