7 QC Tools for Process Improvement | PDF | Case Study

What are 7 QC Tools?

→ 7 QC tools are systematic and scientific methods for problem-solving.

→ Also, they are used for product and process improvement.

→ They are used to solve almost 90% of shop floor problems very easily.

Table of Contents:

• What are 7 QC Tools?
• History of 7 QC Tools
• When to Use the Basic 7 QC Tools?
• Why to Use the 7 QC Tools?
• The Basic 7 QC Tools For Process Improvement
• Flow Chart
• Cause and Effect Diagram (Fishbone or Ishikawa) 
• Checksheet
• Histogram
• Pareto Chart
• Scatter Diagram
• Control Chart
• Benefits of 7 QC Tools
• Limitations of 7 QC Tools
• Conclusion

History of 7 QC Tools:

→ The Basic 7 Quality Control Tools originated after World War II in Japan.

→ Dr. Edwards Deming has played an important role in introducing statistical quality control methods.

→ He recommends the use of statistical methods to improve manufacturing quality.

→ After his work, Japanese industries have improved a lot in quality and processes in manufacturing.

→ Primarily Kaoru Ishikawa introduced the 7 QC Tools.

→ Dr. Kaoru Ishikawa was a professor at the engineering college at Tokyo University.

→ Ishikawa is known for the “Democratizing (Visual Aids/Symbols) Statistics”.

→ Good visual representation makes statistical and quality control more comprehensive.

→ The Basic 7 QC Tools gained popularity for their simplicity and effectiveness across the world.

When to Use the Basic 7 QC Tools?

→ The Basic 7 Quality Control Tools are necessary for problem-solving and process improvement.

→ Each tool has its own specific applications and benefits.

⏩Refer to the below-mentioned key points when we can use 7 QC tools:

• For identifying potential causes of a problem
• Useful during brainstorming sessions
• When collecting data in a structured manner
• For monitoring process trends or patterns over time
• During the identification of the distribution of data
• Prioritization of defects, causes, efforts, etc
• Identify or validate the correlation between two variable
• Process flow documentation, analysis, and improvement

Why to Use the 7 QC Tools?

• A graphical technique that is easily understood by all
• Most helpful in troubleshooting quality-related issues
• They are fundamental tools for process and product quality improvement
• This facilitates the organization to resolve basic problems
• The 7 QC tools are easy to understand and implement
• They do not require complex analytics and statistical skills
• The basic 7 QC tools are simple yet powerful
• We can get an 80% result by applying 20% of the effort

The Basic 7 QC Tools For Process Improvement:

➝ Now we will understand the Basic 7 QC Tools in detail.

⏩The 7 QC Tools are:

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

Note: We are considering the Flow Chart as a part of the 7 Basic QC Tools.

Also, you can consider stratification as a part of this tool.

(1) Flow Chart:

→ "Flow Chart 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 sequence of operations, therefore, we can easily illustrate the Internal and external operational boundaries.

→ A flow chart includes the steps involved in a process, the decision points, and the flow of control from one step to the next.

→ A flow chart is also called a "Process Flow Diagram."

⏩Purpose of Flowcharts:

• Visualize Processes
• Identify Inefficiencies
• Standardize Procedures

⏩Basic Elements of the Process Flow Diagram are:

• Start
• Steps
• Decision
• Outcomes
• End

⏩Basic Symbols Used in Flowcharts:

• Symbol
• Oval
• Rectangle
• Diamond
• Arrow
• Parallelogram

⏩Steps to Create a Flowchart:

• Define the Process
• List Steps
• Select Symbols
• Draw the Flowchart
• Review and Revise

⏩Benefits of Using Flowcharts:

• Clarity
• Improvement
• Communication

⏩Use Cases:

• Process mapping in manufacturing and service industries
• Identifying areas for quality improvement in workflows
• Documenting procedures for training and compliance

👉 Read our detailed article on Different Types of Flow Charts Explained with Examples

(2) Cause and Effect Diagram (Fishbone or Ishikawa):

→ "Cause and Effect Diagram is a meaningful relationship between an effect and its causes."

→ 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.

→ The cause and effect tool is a very popular root cause analysis tool.

⏩The Different Names of Cause and Effect Diagram are:

• Ishikawa Diagram
• Fishbone Diagram
• Herringbone Diagrams
• Fishikawa

→ A fishbone diagram can identify all possible cause(s) for the problem.

→ In this tool, we can find possible causes with the help of the 6M concept those are man, machine, material, method, measurement, and mother nature.

→ Also, we can use this tool in marketing as 8P analysis and service industry as 4S analysis.

⏩Steps to Create a Cause and Effect Diagram:

• Define the Problem
• Identify Main Categories
• Brainstorm Causes
• Analyze and Prioritize

⏩Benefits of Using a Cause and Effect Diagram:

• Visual Representation
• Team Collaboration
• Problem-Solving

⏩Use Cases of Cause and Effect Diagram:

• Quality improvement projects
• Problem-solving in manufacturing
• Analyzing service delivery issues

👉 Check our detailed article on Cause and Effect Diagram Explained with Case Study

(3) Check Sheet:

→ "Check Sheet is a well-structured data sheet that is used for collecting and analyzing data." 

→ Data collected by the check sheet is used as input for the other tool and data can be collected based on asking a question by what, when, where, who, why, and how.

→ The purpose of a check sheet 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.

⏩Key Aspects of a Check Sheet:

• Structured Form
• Real-Time Data Collection
• Ease of Use
• Data Visualization

⏩Uses of a Check Sheet:

• Defect Tracking
• Data Collection
• Process Improvement
• Quality Control

👉 Read our detailed article on Different Types of Check Sheets Explained with Example

(4) Histogram:

→ "Histogram is a type of bar graph representing the frequency distribution of the data."

→ Karl Pearson introduced the Histogram which is a bar graph representing the frequency distribution on every bar.

→ Histograms are used to show whether the output of our process matches the customer's requirements or not?

→ Also, we can make the decision based on the data patterns plotted on the Histogram.

→ With the help of the graph we can analyze whether the process is capable of meeting customer requirements or not?

→ A histogram is a pictorial representation of a set of data.

⏩Key Aspects of a Histogram:

• Frequency Distribution
• Bars
• Intervals (Bins)
• Patterns

⏩Steps to Create a Histogram:

• Collect Data
• Determine the Range
• Choose Intervals (Bins)
• Count Frequencies
• Draw the Bars
• Interpret the Patterns

⏩Uses of a Histogram:

• Understanding Data Distribution
• Identifying Patterns
• Process Improvement
• Quality Control

⏩Different Types of Histogram are:

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

👉 Also read a detailed article on Different Types of Histograms Explained with Case Study

(5) Pareto Chart:

→ "Pareto Chart is a bar graph arranged in descending order of height from left to right."

→ Pareto chart shows the order of the largest number of occurrences by item or by classes and the cumulative sum total.

→ The Pareto analysis helps us to prioritize where we can get more benefits by applying fewer efforts.

→ It is also very popular as a prioritization tool.

→ It communicates the principle of 80:20.

→ The Pareto Principle gives us information about the Vital few from Trivial many.

→ Hence,  It is known as the "Vital few from Trivial many tool".

→ It states that 80% of an effect comes from 20% of the causes.

⏩Key Aspects of a Pareto Chart:

• Bars
• Cumulative Line
• 80/20 Rule

⏩Steps to Create a Pareto Chart:

• Identify Problems/Causes
• Measure Frequency or Impact
• Sort Data
• Calculate Cumulative Percentages
• Draw the Chart

⏩Uses of a Pareto Chart:

• Prioritizing Problems
• Resource Allocation
• Process Improvement
• Quality Control

👉 Read our detailed article on Pareto Chart Explained with Case Study

[6] Scatter Diagram:

→ "Scatter Diagram is used to study and identify the possible relationship between two variables."

→ It is used to identify and visualize the relationship between two variables.

→ Mostly the scatter diagram is used to validate the cause-and-effect relationships between two variables.

→ This tool helps in decision-making during the problem-solving process.

→ Also it helps to determine the correlation between two variables.

→ Scatter Diagram is the best validation tool.

⏩Different names of the Scatter Diagram:

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

⏩Key Aspects of a Scatter Diagram:

• Axes
• Data Points
• Correlation

⏩Steps to Create a Scatter Diagram:

• Identify Variables
• Collect Data
• Plot Data Points
• Analyze the Pattern

⏩Types of Correlation:

• Positive Correlation
• Negative Correlation
• No Correlation

⏩Uses of a Scatter Diagram:

• Identifying Relationships
• Predicting Trends
• Quality Control
• Problem-Solving

👉 Also visit our detailed article on Scatter Diagram Explained with Example

[7] Control Chart:

→ "Control Charts are used for studying the process variation over time." 

→ The control chart was invented by Walter A. Shewhart working for Bell Labs in the 1920s.

→ A control chart is also known as a Shewhart chart or process-behavior chart.

→ With the help of this tool, we can determine whether a manufacturing process or a business process is in control or not?

→ The control chart is a graph which is used to study process changes over time

→ Comparing the above tool this is the best forecasting tool.

⏩Key Aspects of a Control Chart:

• Data Points
• Center Line (CL)
• Upper Control Limit (UCL)
• Lower Control Limit (LCL)
• Control Limits

⏩Steps to Create a Control Chart:

• Collect Data
• Calculate the Mean
• Calculate Control Limits
• Plot the Data
• Analyze the Chart

⏩Types of Control Charts:

• X-bar Chart
• R Chart
• P Chart
• C Chart
• U Chart

⏩Uses of a Control Chart:

• Monitoring Processes
• Identifying Variation
• Quality Control
• Process Improvement

👉 Read our detailed article on Control Chart Explained with Case Study

Benefits of 7 QC Tools:

• Provides a structured approach for problem-solving
• Easy to understand
• Easy to implement
• A scientific and logical approach
• Improve the quality of products and services
• Identifying and analyzing problems
• Used for root cause analysis
• Enhance customer satisfaction

Limitations of 7 QC Tools:

• The accuracy of data collection depends on a person's skills
• Statistical interpretation requires highly skilled persons
• They are focused on identifying problems rather than preventing
• Reactive approach
• Focus on symptoms, not on root causes

Conclusion:

→ Seven QC tools are most helpful in troubleshooting issues related to quality

→ Different factors cause different effects on the process and make them unstable.

→ Those parameters cause variation in the process.

→ These tools are the most helpful for improving the process.

→ We can improve the efficiency and effectiveness of processes by using these tools.