7 quality control tools
- 1. 7 QUALITY CONTROL TOOLS By Vima Mali
- 2. INTRODUCTION The 7 QC Tools are simple statistical tools used for problem solving. These tools were either developed in Japan or introduced to Japan by the Quality Gurus such as Deming and Juran. In terms of importance, these are the most useful. Kaoru Ishikawa has stated that these 7 tools can be used to solve 95 percent of all problems. These tools have been the foundation of Japan's astomishing industrial resurgence after the second world war.
- 3. Cost of Quality 1. Prevention costs 2. Appraisal costs(Companies pay appraisal costs as part of the quality control process to ensure that their products and services meet customer expectations and regulatory requirements.) 3. Internal failure costs 4. External failure costs 5. Opportunity costs
- 5. Continuous improvement philosophy 1. Kaizen: Japanese term for continuous improvement. A step-by-step improvement of business processes. 2. PDCA: Plan-do-check-act as defined by Deming. Plan Do Act Check 3. Benchmarking
- 6. What is total Quality management? A core definition of total quality management (TQM) describes a management approach to long–term success through customer satisfaction. In a TQM effort, all members of an organization participate in improving processes, products, services, and the culture in which they work.
- 7. After World War II the Japanese adopted 'quality' as a philosophy for economic recovery and, in line with this traditional approach, sought seven tools to accomplish the economic rejuvenation. The seven tools chosen were For solving quality problems following seven QC tools are required 1. Pareto Diagram 2. Cause & Effect Diagram 3. Histogram 4. Control Charts 5. Scatter Diagrams 6. Graphs 7. Flow Chart
- 8. All this tools are important tools used widely at manufacturing field to monitor the over all operation and to improve the manufacturing process. The modes of defects on production line are investigated through direct observation on the production line and statistical tools.
- 9. What is a Cause and Effect Diagram?. A graphic tool that helps identify, sort, and display possible causes of a problem or quality characteristic.
- 10. Cause and Effect Diagram Purpose: Graphical representation of the trail leading to the root cause of a problem. Characteristics: Decide which quality characteristic, outcome or effect you want to examine (may use Pareto chart). Backbone –draw straight line. Ribs – categories. Medium size bones –secondary causes. Small bones – root causes.
- 11. STEPS TO CONSTRUCT First, clearly identify and define the problem or effect for which the causes must be identified. Place the problem or effect at the right or the head of the diagram. Identify all the broad areas of the problem. Write in all the detailed possible causes in each of the broad areas. Each cause identified should be looked upon for further more specific causes. View the diagram and evaluate the main causes. Set goals and take action on the main causes.
- 17. APPLICATIONS Helps determine root causes. Encourages group participation. Uses an orderly, easy-to-read format. Indicates possible causes of variation. Increases process knowledge. Identifies areas for collecting data.
- 18. Flow chart What Is a Flowchart? A diagram that uses graphic symbols to depict the nature and flow of the steps in a process.
- 19. BENEFITS OF USING FLOWCHARTS Promote process understanding. Provide tool for training. Identify problem areas and improvement opportunities.
- 21. HISTOGRAM Histogram Defined A histogram is a bar graph that shows frequency data. Histograms provide the easiest way to evaluate the distribution of data.
- 22. Benefits: Allows you to understand at a glance the variation that exists in a process. The shape of the histogram will show process behavior. The shape and size of the dispersion will help identify otherwise hidden sources of variation. Used to determine the capability of a process. Starting point for the improvement process.
- 23. PARETO CHART Pareto Principle Vilfredo Pareto (1848-1923) Italian economist 20% of the population has 80% of the wealth. Adapted by Joseph Juran. Remember the 80/20 rule states that approximately 80% of the problems are created by approximately 20% of the causes.
- 24. PARETO CHARTS PURPOSE: Prioritize problems. HOW IS IT DONE? Create a preliminary list of problem classifications. Tally the occurrences in each problem classification. Arrange each classification in order from highest to lowest Construct the bar chart
- 25. PARETO CHARTS Benefits: Pareto analysis helps graphically display results so the significant few problems emerge from the general background. It tells you what to work on first. 0 20 40 60 80 100 120 Quantity Defects 104 42 20 14 10 6 4 Dent Scratch Hole Others Crack Stain Gap
- 26. Pareto Charts • Weighted Pareto charts use the quantity of defects multiplied by their cost to determine the order. 0 100 200 300 400 500 600 700 800 900 WeightedCost Weighted cost 800 208 100 80 42 14 6 Gap Dent Hole Crack Scratch Others Stain Defect Total Cost Weighted cost Gap 4 200 800 Dent 104 2 208 Hole 20 5 100 Crack 10 8 80 Scratch 42 1 42 Others 14 1 14 Stain 6 1 6
- 28. SCATTER DIAGRAMS When solving a problem or analyzing a situation one needs to know the relationship between two variables. A relationship may or may not exist between two variables. If a relationship exists, it may be positive or negative, it may be strong or weak and may be simple or complex. A tool used to study the relationship between two variables is known as Scatter Diagram.
- 29. It consists of plotting a series of points representing several observations on a graph in which one variable is on X-axis and the other variable in on Y-axis. The way the points lie scattered in the quadrant gives a good indication of the relationship between the two variables.
- 30. Check sheets are tools for collecting data. They are designed specific to the type of data to be collected. Check sheets aid in systematic collection of data. Some examples of check sheets are daily maintenance check sheets, attendance records, production log books, etc. Data collected using check sheets needs to be meaningfully classified. Such classification helps gaining a preliminary understanding of relevance and dispersion of the data so that further analysis can be planned to obtain a meaningful output. CHECK SHEETS
- 31. Check sheets Purpose: –Tool for collecting and organizing measured or counted data. –Data collected can be used as input data for other quality tools. Benefits: –Collect data in a systematic and organized manner. –To determine source of problem. –To facilitate classification of data (stratification).
- 33. GRAPHS Graphs of various types are used for pictoral representation of data. Pictoral representation enables the user or viewer to quickly grasp the meaning of the data. Different graphical representation of data are chosen depending on the purpose of the analysis and preference of the audience. The different types of graphs used are as given below :
- 34. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements constitute the work breakdown structure of the project.
- 35. Line graph A line graph, also known as a line chart, is a type of chart used to visualize the value of something over time. For example, a finance department may plot the change in the amount of cash the company has on hand over time.
- 36. Radar Charts are a way of comparing multiple quantitative variables, Radar Charts are also useful for seeing which variables are scoring high or low within a dataset, making them ideal for displaying performance.
- 37. A band diagram does however try to show the changes in the band structure from place to place.