7 QC Tools | 7 Basic Quality Tools | What are the 7 QC Tools for Process Improvement?

7 QC Tools | 7 Basic Quality Tools | What are 7 QC Tools for Process Improvement?

7 QC tools is a systematic and scientific method for Problem Solving.
➞ It is used for solve 90% of shop floor problem very easily.


1) What are the 7 QC Tools for Process Improvement?

 7 QC tools are the systematic and scientific approach to the Problem Solving Technique.
 It improves our workplace.
 Can be used to solve 90% of workplace problems.


2) From Where did the 7 QC Tools come?

 Primarily Kaoru Ishikawa introduced the 7 QC Tools.
 Ishikawa has known for the “Democratizing (Visual Aids/Symbols) Statistics”.
 Good visual aids make statistical and quality control more comprehensive.
 Dr. Kaoru Ishikawa was a professor of the engineering college at Tokyo University.


3) Why we use The 7 QC Tools for Process Improvement?

The 7 QC tools for Process Improvement is a set of graphical techniques identified as being most helpful in troubleshooting issues related to quality.
→ The 7 QC tools are fundamental instruments to improve the process and product quality.
→ It is used to examine the production process, identify the key issues, control fluctuations of product quality, and give solutions to avoid future defects.
→ This facilitates the organization to resolve the basic problems.
→ A most likely organization uses the basic 7 QC Tools for quality improvements of Product, Process or Service.
→ These 7 QC tools are easy to understand and implement and they do not need complex analytical/ statistical competence, hence it is simple yet powerful.

4) The 7 QC Tools are:

  1. Flow Charts
  2. Cause and Effect Diagram (Fishbone diagram or Ishikawa Diagram) 
  3. Checksheet
  4. Histogram
  5. Pareto Chart
  6. Scatter Diagram
  7. Control Chart

[1] Flow Charts in 7 QC Tools:

→“Flowchart is a diagrammatic representation that illustrates the sequence of operation to be performed to get the desired result.”
 A flow chart is a visual representation tool for a process, therefore, the process easily illustrates the Internal and external operational boundaries.


➥ Types of Flow Charts:

  1. Macro Flow Chart
  2. Mini Flow Chart
  3. Micro Flow Chart
  4. Matrix Flow Chart
Flow Charts in 7 QC Tools

→ “A diagram which represents a meaningful relationship between an effect and its causes are called the Cause & Effect Diagram."
→ Another name of Cause and effect diagram is a Fishbone Diagram or Ishikawa Diagram.
 It guides concrete action and tracks the potential causes during an investigation of the effort to determine whether the item significantly contributes to the problem or not.


➥ Different names of the Ishikawa Diagram:

  1. Fishbone Diagram
  2. Cause and effect diagram
  3. Herringbone diagram
  4. Cause and effect diagram, or 
  5. Fishikawa
(Source: Wikipedia)

7 QC Tools Fishbone Diagram | Cause and effect diagram | Ishikawa diagram

[3] Check Sheet:

→ "Check Sheet is a structured, prepared form for collecting and analyzing data." 
→ The purpose of a checklist is to summarize the data and a tally count of event occurrences.
→ A check sheet counts the number of occurrences of an event, such as defects or non-conformance.
→ Hence the Check Sheet is also called a "tally sheet ".
→ In many cases, a checklist will summarize countable data related to certain types of defects and will provide a rough graphical representation of wherein a part of the process, defects occurred.

7 QC Tools Check Sheet

[4] Histogram in 7 QC Tools:

→ “Histogram is a type of bar chart representing the frequency distribution of the data from a process.” 
→ Karl Pearson introduced Histogram and it is a bar graph representing the frequency distribution on its every bar.
→ The histogram is the best Frequency distribution tool.
→ A histogram is a pictorial representation of a set of data.


➥ Types of Histogram chart:

  1. Normal Distribution
  2. Skewed Distribution
  3. Double-Peaked or Bimodal
  4. Multipeaked or Multimodal
  5. Edge Peaked Histogram
  6. Truncated or Heart cut Histogram

Histogram in 7 QC Tools

[5] Pareto Chart in 7 QC Tools:

→ "Pareto chart is a bar graph arranged in descending order of height from left to right”
→ It is a diagram that shows the order of the largest number of occurrences by item or by classes and the cumulative sum total.
→ Pareto Chart communicates the principle of 80:20, therefore the Pareto Chart is an 80:20 analysis chart.
→ The Pareto Chart also gives us information about Vital few from Trivial many, Hence, Pareto chart is "Vital few from Trivial many".
→ It states that 80% of an effect comes from 20% of the causes.


Pareto Chart in 7 QC Tools

[6] Scatter Diagram:

→ “Scatter Diagram is used to study and identify the possible relationship between two variables”.
→ It is the best validation tool.


➥ Different names of the Scatter Diagram:

  1. Scatter Plot
  2. Scatter Graph
  3. Correlation Chart
  4. Scatter Chart
  5. Scatter Gram

➥ Different correlation between two variables in the Scatter Diagram:

  1. Strong Positive
  2. Moderate Positive correlation
  3. Weak Positive correlation
  4. Strong Negative correlation
  5. Moderate Negative correlation
  6. Weak Negative correlation
  7. Random Pattern (No correlation)
7 QC Tools Scatter Diagram

[7] Control Chart:

→ “Control chart is a type of run chart used for studying the process variation over time." 
→ Most importantly, the control chart is a time series plot that is used to monitor a process over time.
→ It is a plot of a process characteristic, usually through time with statistically determined limits.
→ When used for process monitoring, it helps the user to determine the appropriate type of action to take on the process depending on a degree of variation in the process.
→ With comparing above all tool Control Chart is the best process forecasting tool.


7 QC Tools Control Chart

5) Benefits of the 7 QC Tools:

➝ It encourages the way of problem-solving and improvement.
7 QC Tools are very simple to use but it is very powerful.
➝ It is a scientific approach for problem-solving.
➝ We can get an 80% result by applying 20% of the effort.
➝ Each tool has its own specialty for problem solving and analysis.
➝ It is very easy to understand, communicate and use by the shop floor operator.