7QC Tools for Problem Solving | What are 7 QC Tools

7QC Tools for Problem Solving | What are 7 QC Tools

7QC Tools for Problem Solving technique are generally used in manufacturing, Non-manufacturing industries and service sectors to resolve the problems.

Definition and History:-

The 7QC Tools (Also Known as “Seven Basic Tools of Quality”) originated in Japan. First emphasised by Kaoru Ishikawa, a professor of engineering at Tokyo University and the father of “quality circles”. Theses tools are used to solve the  critical quality related issues. You can use the 7 basic tools of quality to help understand and solve problems or defects in any industry. By the help of Excel you can plot the graphs / Diagram to resolve the daily quality problems. I will help you to understand the basic ideas and knowledge of 7QC Tools and its usages.

For solving problems seven QC tools used as Pareto Chart, Cause & Effect Diagram, Histogram, Control Charts, Scatter Diagrams, Graphs/Process Flow Diagram and Check Sheets. All these tools are important tools used widely at manufacturing field to monitor the overall operation and continuous process improvement. seven QC tools are used to find out the Root cause of the Problem and implement the action plan to improve the process efficiency.

7QC tools are :-

  1. Pareto Chart
  2. Cause and effects diagram
  3. Histogram
  4. Scatter Diagram
  5. Control Chart
  6. Check Sheet
  7. PFD(Process Flow diagram)/Graphs

 Benefits of 7QC Tools:-

 

  • Improve management decision.
  • Simple and easy for implementation
  • Continuous quality improvement
  • Quick results
  • Enhances customer satisfaction through improved quality product
  • Reduce cycle time and improve efficiency
  • Control cost of poor quality / Cost of quality
  • Reduce defects and optimize the production
  • Reduce variations and improve quality of Products
  • Encouragement of teamwork and confidence
  • Enhancement of customer focus.

Pareto Chart:-

A Pareto Chart named after the Italian Economist Vilfredo Pareto. It is a type of chart which contain both bars and line graph, where the individual values represent in bar graph in descending order (largest to smallest value) and cumulative percentage is represented in the line graph.

Click here to know “How to Plot Pareto Chart In Excel”.

Understanding the Pareto Chart principle (The 80/20 rule): 

The Pareto principle also known as the 80/20 rule derived from the Italian Economist Vilfredo,

The principle is understood as –

20% of the input creates 80% of the results

Or

80 % of the effects come from 20% of the causes.

[Figure-1]

In the above Pareto Chart[Figure-1] , we can see the cumulative% in line graph , According to the Pareto Chart principle 80/20 rule, the 80% cumulative in line graph is filling under the low hardness , it means BH, Damage, SH and Low hardness defers are coving the 80% of contribution over total types of defects. And those 80% contribution was due to the 20% of caused.

 Histogram:-

Histogram is a one of the 7QC tools, which is most commonly used graph to show frequency distribution.

Helps summaries data from process that has been collected over period of time.

Click here to know the “How to Plot Histogram in Excel:.

[Figure-2]

Fish-bone Diagram/Cause and Effects /Ishikawa Diagram:-

Cause and Effects Diagram is look like a fish that’s why it’s called Fish-bone Diagram, also called Ishikawa diagram.

It’s a visualisation tool for categorising the potential causes of a problem in order to identify its root causes.

CFT members are identifying the potential cause through Brainstorming process of individual and together.

 The Potential cause is related w.r.t below as-

  • Machine
  • Manpower
  • Environment
  • Method
  • Materials
  • Measurement

[Figure-3]

 

 

Scatter diagram:-

The scatter diagram graphs pairs of variable data, with one variable on each axis, to look for a relationship between them. If the variables will correlate, the points will fall along a line or curve. The better the correlation, the points will strongly cluster to the line. It’s is generally gives the idea about the correlation between the variables.

[Figure-4]

In the above figure-4, the positive and Negative correlation is only due to the direction and in both the correlation, points are cluster to line but in the last figure in figure-4, Points are not cluster to line but  spread over the X and Y axis.  

Control Chart:-

A line on a control chart used as a basis for judging the stability of a process. If the observe points are beyond a control limit then it is evidence that special causes are affecting the process.

Control Chart can use to monitor or evaluate a process.

There are basically two types of control charts, those for variable data and those for attributes data.

Click here to know more about the Control Chart and Statistical Process Control. 

Benefits :-Higher Quality, Lower Unit Cost, Higher effective Capability etc.

 

Selection of Control Charts based on Attribute / Variable Type Data:-

 

Calculation of Average and Range Charts-

 

Formula of Attributes Control Chart:-

 

Nomenclature of Control Chart:-

 

Check Sheet:-

Check Sheet is a simple document use for collecting data in real time. Variable or Attribute type’s data collects through Check sheet. Check sheet are generally helps to take the decision on facts basis and to collect the data for analysis and evaluation.

Sample check Sheet:-

Logo Title:-……… Format No-

Issue no-…  rev. no-

Date-

Parameters Specification Observations Remarks
           Checked by:-                                                                  Verified by:-

 

Process Flow diagram/Graphs:-

A process flow diagram is a diagram uses to indicate the general flow of plant processes and equipment.

 

 

 

 

 

 

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