Seven Old Tools of Quality Management Dr. Mohamed RiyazhKhan - DoMS

Seven QC Tools Flow Charts Check Sheets Histograms Pareto Diagrams Cause and Effect Diagrams Scatter diagrams Control Charts To analyze Quantitative Data

Flow Chart A Flow chart or Process map identifies the sequence of activities or the flow of materials and information in a process. Help the people involved in the process understand it better and more objectively by providing a picture of steps needed to accomplish a task.

Flow charts are best developed by having the people involved in the process – employees, supervisors, managers and customers. Once constructed, it can be used to identify quality problems as well as areas for productivity improvement

Check Sheets Check Sheets are special types of data collection forms in which the results may be interpreted on the form directly without any additional processing.

Histograms Histograms provide clues about the characteristics of the parent population from which a sample is taken. Patterns that should be difficult to see in an ordinary table of numbers become apparent.

Pareto Diagram A Pareto diagram is one in which the characteristics observed are ordered from largest frequency to smallest. This is based on the principle of an Italian economist Vilfredo Pareto.(1848-1923). He observed during his study on the distribution of wealth that 80% of the wealth is owned by 20% of population.

For example,   -80% of money is spent on 20% of machines and materials. -80% of defects one due to 20% of causes (root causes) -80% of problems in a society come form 20% of people -80% of sales due to 20% of customers. -80% of complaints due to 20% defects.

  No. % Dimensional Error Geometrical error Surface scratch Surface finish 9 6 42 3 15 10 70 5 60 100

PARETO DIAGRAM A. Dimensional Error 9 9 B. Geometrical error 6 6 60 50 40 30 20 10 PARETO DIAGRAM A. Dimensional Error 9 9 B. Geometrical error 6 6 C. Surface scratch 42 4 D. Surface finish 3 3 C A B D A B C D Before Solving the problem After Solving the problem

Construction of a Pareto diagram Determine the methods of classifying the data by problem, cause, non- conformity etc, Decide the factors to be used to rank the characteristics Collect data an appropriate time interval Summaries the data and rank order from largest to smallest (descending order) Construct the diagram and find the vital few Compute the cumulative values in number and percentage and plot the cumulative curve. After solving a problem, repeat steps 4 through 6 and compare the diagrams and measure the percentage improvements

Cause and Effect Diagram It is a simple graphical method for presenting a chain of causes and effects and so for sorting out causes and organizing relationships between variables. Introduced by Kaoru Ishikawa in Japan, so called as Ishikawa diagram. Because of its structure it is called as Fishbone diagram.

CAUSE AND EFFECT DIAGRAM . METHOD MAN STORE BIN ARRANGMENT CARELESSNESS TRANSPORT SCRATCH SOFT WORK HOLDING MEASURMENT MATERIAL MACHINE CAUSE AND EFFECT DIAGRAM

The diagrams are useful to : Analyze actual conditions for the purpose of product or service quality improvement, more efficient use of resources and reduced costs. Eliminate conditions causing nonconformities and customer complaints. Standardize existing and proposed operations. Educate and train personnel in decision making and corrective action activities.

Scatter Diagrams A scatter diagram is graphical representation of relationship between two variables, one variable is called independent variable, and the other is called dependent variable.