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Ko ç Un iversity. OPSM 301 Operations Management. Class 21: Quality. Zeynep Aksin zaksin @ku.edu.tr. Variability = Actual - Expected. Customer Needs - Product Design Product Design - Process Capability Process Capability - Process Performance Process Performance - Product Performance
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Koç University OPSM 301 Operations Management Class 21: Quality Zeynep Aksin zaksin@ku.edu.tr
Variability = Actual - Expected • Customer Needs - Product Design • Product Design - Process Capability • Process Capability - Process Performance • Process Performance - Product Performance • Product Performance - Customer Perception
Ways in Which Quality Can Improve Profitability Sales Gains • Improved response • Higher prices • Improved reputation Improved Quality Increased Profits Reduced Costs • Increased productivity • Lower rework andscrap costs • Lower warranty costs
Quality Costs • Cost of Control (Quality, Conformance) • Prevention costs: reducing the potential for defects • Appraisal costs: evaluating products • Cost of Failure of Control (Unquality, non-conformance) • Internal failure costs:of producing defective parts or service • External failure costs: occur after delivery
Stage: At Source Next Process End of Line Final Inspection End User Cost: Impact: • Little • Minor • Rework • Much rework • Warranty delay • Reschedule • Delivery delay • Complaints • Inspect more • Reputation • Market share Early Defect Detection Saves Prevention Saves Even More!
International Quality Standards • ISO 9000 series • Common quality standards for products sold in Europe (even if made in U.S.) • 2000 update places greater emphasis on leadership and customer satisfaction • ISO 14000 series • Environmental management • Auditing • Performance evaluation • Labeling • Life cycle assessment
P D C A P D C A TQM: Continuous Process Improvement • Measurement • External and Internal • Analysis • Analyze Variation • Control • Adjust Process • Improvement • Reduce Variation • Innovation • Redesign Product/Process Improve Innovate Improve Control
Analytical Tools for Continuous Improvement • Process Analysis • Pareto Charts • Histograms • Scatter Diagrams • Fish-Bone Charts • Control Charts
Type of Defect Number of Defective Flow Units Cost Response Time Customization Service Quality Garage Quality Check Sheet
Pareto Analysis • The purpose of Pareto Analysis is to identify and highlight major symptoms of major quality problems • It is based on the premise that usually a small number of faults cause the majority of malfunctions (to separate the vital few and trivial many)
Developing Pareto Analysis • Define classification of defects to be monitored • Define the period of time over which the assessment will be made • Total the frequency of occurrence of each class of defects over the period • Plot the histogram and cumulative distribution of the classes in descending order of the frequency occurrence • Identify the classes that constitute the majority of defect occurrences
Pareto Analysis -100% Percentage Frequency -50% -0% A B C D E F Pareto Law (80/20 Rule): “80 percent of the problems are due to 20 percent of the causes”
Fish-Bone Diagram • Also known as cause-and-effect diagram, or Ishikawa diagram • Pareto analysis is used to identify key problems or symptoms, • Fish-Bone diagram is used to sort causes of the problems • Brain storming sessions of groups of workers needed • It is a very valuable educational tool
Fish-Bone Diagram • Used to find problem sources/solutions • Other names • Fish-bone diagram, Ishikawa diagram • Steps • Identify problem to correct • Draw main causes for problem as ‘bones’ • Ask ‘What could have caused problems in these areas?’ Repeat for each sub-area.
Method (shooting process) Material (ball) Grain/Feel (grip) Aiming point Size of ball Bend knees Air pressure Hand position Balance Lopsidedness Follow-through Missed free-throws Training Rim size Conditioning Rim height Motivation Rim alignment Consistency Backboard stability Concentration Machine (hoop & backboard) Manpower (shooter) Cause-and-Effect Diagrams
1 4 1 2 1 0 8 Frequency 6 4 2 0 7 2 7 4 7 6 7 8 8 0 8 2 8 4 8 6 8 8 9 0 9 2 Weight (kg) Histogram
Announcement • Last 2 assignments announced on web page • Based on the Toyota case • See Web page to download a copy • First one due in one week