7 QC Tools | 7 Basic Quality Tools for Process Improvement

7 QC Tools for Process Improvement

➞ 7 QC tools is a systematic and scientific method for Problem Solving.
➞ It is used to solve 90% of shop floor problems very easily.
→ 7 QC tools are the systematic and scientific approach to the Problem Solving Technique.
→ It improves our workplace.
→ It can be used to solve 90% of workplace problems.

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.

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.
→ It is a fundamental concept to improve the process and product quality.
→ It is used to examine the production sequence, 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.
→ 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.

Benefits of the 7 QC Tools:

➝ It encourages the way of problem-solving and improvement.
➝ They 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.

The 7 QC Tools:

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

➤ [1] Flow Charts:

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

 Flow Chart

➤ [2] Cause and Effect Diagram:

→ “A diagram which represents a meaningful relationship between an effect and its causes is called the Cause & Effect 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.

Cause and Effect Diagram (Fishbone diagram or 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.

Check Sheet

➤ [4] Histogram:

→ “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:

  • Normal Distribution
  • Skewed Distribution
  • Double-Peaked or Bimodal
  • Multipeaked or Multimodal
  • Edge Peaked Histogram
  • Truncated or Heart cut Histogram


➤ [5] Pareto Chart:

→ "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.
→ It communicates the principle of 80:20.
→ The Pareto Chart also gives us information about Vital few from Trivial many, Hence,  It is "Vital few from Trivial many".
→ It states that 80% of an effect comes from 20% of the causes.

Pareto Chart

➤ [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:

  • Scatter Plot
  • Scatter Graph
  • Correlation Chart
  • Scatter Gram

➥ Different correlation between two variables in the Scatter Plot:

  • Strong Positive
  • Moderate Positive correlation
  • Weak Positive correlation
  • Strong Negative correlation
  • Moderate Negative correlation
  • Weak Negative correlation
  • Random Pattern (No correlation)
Scatter Diagram

➤ [7] Control Chart:

→ “Control chart is a type of run chart used for studying the process variation 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.
→ Comparing above all tool Control Chart is the best forecasting tool.

Control Chart

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