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IENG 451 - Lecture 09

IENG 451 - Lecture 09. Data Collection: 7 Tools of Ishikawa. Ishikawa’s “Magnificent Seven” Tools. The Seven Tools are: Histogram / Stem & Leaf Diagram Pareto Chart Cause & Effect (Fishbone) Diagram Defect Concentration Diagram Check Sheet Scatter (Plot) Diagram

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IENG 451 - Lecture 09

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  1. IENG 451 - Lecture 09 Data Collection: 7 Tools of Ishikawa IENG 451 Operational Strategies

  2. Ishikawa’s “Magnificent Seven” Tools • The Seven Tools are: • Histogram / Stem & Leaf Diagram • Pareto Chart • Cause & Effect (Fishbone) Diagram • Defect Concentration Diagram • Check Sheet • Scatter (Plot) Diagram • Control Chart - not covered in this course! • The tools were not invented by Ishikawa, but were very successfully put into methodical use by him • The first six are used before starting to use the seventh • They are also reused when needed to find an assignable cause IENG 451 Operational Strategies

  3. Ishikawa’s Tools: Histogram • A histogram is a bar chart that takes the shape of the distribution of the data. The process for creating a histogram depends on the purpose for making the histogram. • One purpose of a histogram is to see the shape of a distribution. To do this, we would like to have as much data as possible, and use a fine resolution. • A second purpose of a histogram is to observe the frequency with which a class of problems occurs. The resolution is controlled by the number of problem classes. IENG 451 Operational Strategies

  4. Divide each number into: Stem – one or more of the leading digits Leaf – remaining digits (may be ordered) Choose between 4 and 20 stems Example: 4| 5| 5| 6| 6| 7| 7| Histogram: Stem-and-Leaf Plot 8 9 7 9 5 3 2 1 2 3 4 9 3 0 4 4 2 0 5 9 Done! IENG 451 Operational Strategies

  5. Histogram Example (Excel) IENG 451 Operational Strategies

  6. Ishikawa’s Tools: Pareto Chart • 80% of any problem is the result of 20% of the potential causes • Histogram categories are sorted by the magnitude of the bar • A line graph is overlaid, and depicts the cumulative proportion of defects • Quickly identifies where to focus efforts IENG 451 Operational Strategies

  7. Ishikawa’s Tools: Fishbone Diagram • Cause & Effect diagram constructed by brainstorming • Identified problem at the “head” • Connects potential causes along the spine • Sub-causes are listed along the major “bones” • Man • Material • Method • Machine • Environment IENG 451 Operational Strategies

  8. Man Method Skill Level Low RPM Attention Level Travel Limits Dusty Environment Poor Conductor Temperature Humidity Poor Mixing Orifice Clogs Poor Vendor Worn Parts Machine Material Bad Paint Cause & Effect Diagram, Cont. • The purpose of the cause and effect diagram is to obtain as many potential influencers of a process, so that the problem solving can take a more directed approach. IENG 451 Operational Strategies

  9. Ishikawa’s Tools: Defect Concentration Diagram • A defect concentration diagram graphically records the frequency of a defect with respect to product location. • Obtain a digital photo or multi-view part print showing all product faces. • Operator tallies the number and location of defects as they occur on the diagram. IENG 451 Operational Strategies

  10. Title Header Info: Date, Time, Location, Operator, etc. Times of Problem Occurrence (periodic) List of Prob Types Raw Data recorded here Statistics For Prob Types Time of Occurrence Statistics Overall Statistics Instructions, settings, comments, etc. Ishikawa’s Tools: Check Sheet • Check sheets are used to collect data (values or pieces of information) in a consistent manner. • List each of the known / possible problems • Record each occurrence including time-orientation. IENG 451 Operational Strategies

  11. Y Y Y X X X Ishikawa’s Tools: Scatter Plot • A scatter plot shows the relationship between any two variables of interest: • Plot one variable along the X-axis and the other along the Y-axis • The presence of a relationship can be inferred or ruled out, but it cannot determine if a cause and effect relationship exists IENG 451 Operational Strategies

  12. VSM Lab Assignment Due THU • Create an AS-IS and a TO-BE Value Stream Map for producing a homemade pizza: • Starting point is deciding what goes on the pizza • Ending point is when you start to chew on the pizza • AS-IS map represents 1st cut process, and includes: • Process steps AND information flows • Appropriate symbols AND process data • Include storage space and material handling times, etc. • TO-BE map represents improvements from 1st cut • Document this in a similar fashion, on a separate map! • Include Value-Analysis / Time Value Map on bottom of both • Non-Value Added to Value Added time ratio (BNVA + NVA) VA IENG 451 Operational Strategies

  13. Questions & Issues IENG 451 Operational Strategies

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