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Chapter 5 – Part 3 The TQM Philosophy Mini Case: Quality Improvement Operation: Adding Toner to Cartridge Current Process USL LSL 20% Defective Mean Target Target Toner X = Amount of Toner Toner Mini Case: Quality Improvement What’s wrong with this operation? How should it be corrected? Why is this fix feasible? Mini Case: Quality Improvement New Process – Mean Shifted to left and centered on target USL LSL Target Amount of Toner Mini Case: Quality Improvement Benefits? Next step? Mini Case: Quality Improvement Suppose the current process looked like this. Will adjusting the mean to the target improve the process? LSL USL 20% Defective Amount of Toner Mean Target Mini Case: Quality Improvement Mean adjusted to target LSL USL 10% Defective 10% Defective Amount of Toner Mean =Target Seven Tools of Quality Control Cause-and-Effect Diagrams Flowcharts Checklists Control Charts Scatter Diagrams Pareto Analysis Histograms Cause-and-Effect Diagram (Fishbone Diagram) Methods Materials Cause Cause Cause Cause Cause Cause Environment Cause Cause Cause Cause Manpower Cause Cause Machines 4M + E Effectproblem Flowcharts Checklist Simple data check-off sheet designed to identify type of quality problems at each work station; per shift, per machine, per operator Control Charts (Chapter 6) Control charts are tools for predicting the future performance of a process. If we can predicting performance, we can take corrective action before too many nonconforming units are produced. Control Charts (Chapter 6) Suppose we construct a control chart for the thickness of the gold plating of an electrical connector. We take samples of connectors over time and compute the mean of each sample. After several time period, we use the sample means to estimate the mean thickness. Control Charts (Chapter 6) We then construct two control limits: an upper control limit (UCL) and a lower control limit (LCL) • We do this by adding subtracting 3 standard deviations to the estimated mean: LCL = Estimated Mean – 3(Standard Deviation) UCL =Estimated Mean + 3(Standard Deviation) Control Charts (Chapter 6) We plot the estimated mean and the control limits on the control chart. The result is called a control chart for the process mean. Mean thickness mean Time Control Charts (Chapter 6) If the sample means fall randomly within the control limits, the process mean is in control. “In control” means that the process mean is stable and hence predictable. If at least one sample mean fall outside of the control limits, we say the process mean is “out of control.” In this case, the process mean is unstable and not predictable. The goal is to find out why and remove the causes of instability from the process. Scatter Diagrams A graph that shows how two variables are related to one another Speed vs. Yield 30 Yield 25 20 15 10 5 0 0 10 20 Speed 30 40 Optimal Speed Pareto Diagram 80% of the problems may be attributed to 20% of the causes. Percent of defects Pareto Principle: 80% Runs Bubbles Missing Cracks Uneven Histograms Histogram for Diameter 45 40 35 30 LSL USL 25 20 15 10 5 0 <=0.077 .077.277 .277.477 .477.677 .677.877 .8771.077 1.0771.277 Diameter 1.2771.477 1.4771.677 1.6771.877 1.8772.077 >2.077 Reliability Reliability is the probability that the product, service or part will function as expected. Reliability is a probability function dependent on sub-parts or components. Reliability Reliability of a system is the product of component reliabilities: RS = (R1) (R2) (R3) . . . (Rn) RS = reliability of the product or system R1 = reliability of the first component R2 = reliability of the second component . . . Rn = reliability of the nth component Example 1: Components in Series A radio has three transistors. All transistors must work in order for the radio to work properly. Probability that the first transistor will work =.80 Probability that the first transistor will work =.90 Probability that the first transistor will work =.85 What is the reliability of the radio? Solution R1 = .80 R2 = .90 RS = (R1) (R2) (R3) RS = (.80) (.90) (.85) =.51 R3 = .85 Example 2: Backup Components Backup component takes over when a component fails. Suppose only one transistor is needed for the radio to work. In case the one transistor fails, a backup transistor has been installed. Probability that the original transistor will work =.92 Probability that the backup transistor will work =.87 Example 2: Backup Components The backup transistor is in parallel to the original transistor. R1 = .92 RBU = .87 Example 2: Backup Components Parallel components allow system to operate if one or the other fails Increase reliability by placing components in parallel For system with one component and a BU component: RS = R1 + [(RBU) x (1 - R1)] 1 - R1 = Probability of needing BU component = Probability that 1st component fails Solution RS = R1 + [(RBU) x (1 - R1)] R1 = .92 RS = .92 + [(.87) x (1 - .92)] = .92 + [(.87) x (.08)] = .9896 RBU = .87 Example 3: Series with Backup Components R1 = .80 RBU = .75 R2 = .88 Example 3: Series with Backup Components • BU is in parallel to first component. • Convert to system in series. • To this by first finding reliability (probability) of components. A = Probability that first component or its BU works B = Probability that second component works = R2 RS = A x B Solution A = R1 + [(RBU) x (1 - R1)] = .80 + [(.75) x (1 - .80)] = .95 Part 1 Part 2 .95 .88 B = R2 =.88 RS = A x B = .95 x .88 = .836 Reliability Over Time - Bathtub Curve Infant Mortality Failure Rate Maturity Constant Failure t0 t1 t2 Time Quality Awards and Standards Malcolm Baldrige National Quality Award (MBNQA) The Deming Prize ISO 9000 Certification MBNQA- What Is It? Award named after the former Secretary of Commerce – Regan Administration Intended to reward and stimulate quality initiatives Given to no more that two companies in each of three categories; manufacturing, service, and small business Past winners: Motorola Corp., Xerox, FedEx, 3M, IBM, Ritz-Carlton Baldrige Criteria Leadership (125 points) Strategic Planning (85 points) Customer and Market Focus (85 points) Information and Analysis (85 points) Human Resource Focus (85 points) Process Management (85 points) Business Results (450 points) The Deming Prize Given by the Union of Japanese Scientists and Engineers since 1951 Named after W. Edwards Deming who worked to improve Japanese quality after WW II Not open to foreign companies until 1984 Florida P & L was first US company winner Based on how well a company applies Deming’s 14 points ISO 9000 Set of international standards on quality management and quality assurance, critical to international business Data based approach to decision making Supplier relationships Continuous improvement Customer focus Leadership Employee training Process (operations) management