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Quality Management Lecture 08. Tools of quality. Ishikawa - 7 tools of quality. They can be used in any order Get the big picture of the process (Flow chart) Collect data about the process (check sheet) Analyze data (histograms, scatter plots, control charts)
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Quality ManagementLecture 08 Tools of quality
Ishikawa - 7 tools of quality • They can be used in any order • Get the big picture of the process (Flow chart) • Collect data about the process (check sheet) • Analyze data (histograms, scatter plots, control charts) • Determine cause roots (Cause & Effect Diagram) • Priorize causes (Pareto analysis) Process Map Check Sheet Histograms Scatter Plots Cause & Effect Diagram Pareto analysis Control Charts
Process Map Decision is needed Step of the process Input/output –information, material goes into/out of the process Start/End Page connector Flowline • Start with a general flow chart, than add the details • Go through the process, ask those who really does the steps • Determine which steps give value and which doesn’t
Video - Kaizen Shortening Lead time
Date Rem. Product Type Check Sheet • Identify common problems (left column) • Create check sheet (Identify time period) • User places check remarks
Histograms • Categorical data frequency charts • Continuous data histograms • Rules • Class width should be the same • Class should be mutually exclusive, and all-inlcusive. • Number of classes (k) • n- number of observations
Example • Determine the sales of a restaurant during launch time. The following dates show the sales ($). Develop a histogram.
Min= 0,79 Max=8,95 Difference=8,16 n=40 k=log40/log2=5,32 k=6 classes Class width: 8,16/6=1,36 Class width: 0,79-2,15 2,16-3,51 3,52-4,87 4,88-6,23 6,24-7,59 7,60-8,95 Solution
Classwidth: 0,79-2,15 2,16-3,51 3,52-4,87 4,88-6,23 6,24-7,59 7,60-8,95 4 11 8 13 2 2 Solution
Scatter Plot • Determine the relationship between two factor • Select factors • Collect dates • Plot data on two-dimensional plane • Observe correlation (with test)
Exercise • A company measure its workers overtime and absenteeism. The table below contains data of 10 workers. Are there any relationship between the dates?
Solution r=0,974 r2=0,95
Ishikawa Diagrams • To find all causes in a systematic way • The 8M (used in manufacturing) • Machine (technology) • Method (process) • Material (Includes Raw Material, Consumables and Information.) • Man Power (physical work)/Mind Power (brain work) • Measurement (Inspection) • Milieu/Mother Nature (Environment) • Management/Money Power • Maintenance
Pareto Chart • To prioritize problems • 20/80 rule • 20 percentage of causes create the 80% of problems • It helps to focus on the biggest problem which’s solution resulted in the highest effect. • Data can be measured in frequency and in value.
Example • The following dates reflects problems in a given process. • a) Use Pareto chart, to determine that causes which have the highest effect on problem. • b) If the cost of problems are the following: A=2$, B=4$, C=3$, D=$7, E=5$, F=3$. Does the results change? A A A B A A B C C E D A B B B C B B C A D A B D A D D D C A A C B B B C C B C A B C A B E A A B D A A A C A A A F C A E
Solution I We should fix problem A, B and C, and thus we can eliminate 81,70% of the problems.
Solution II So we should eliminate problem B, D, A, and thus we can save 73,9% of the costs.
7 new tools for improvement • Affinity diagram • Interrelationship diagram • Tree Diagrams • Priorization Grid • Matrix Diagram • Process Decision Program Chart • Activity Network Diagram
Priorization Grid • Make decisions based on multiple criteria • Steps • Determine goals • Determine criteria • Weight criteria • Ranking criteria on the base of average weights • Rank each alternative with respect to the criteria. (add the rates for each alternative, and determine the ranking) • Multiply the criteria ranking (step 4) by each corresponding alternative’s rank (step 5). The result the importance score • Add the importance score for each alternative • Rank alternatives according to importance