Seven Basic Quality Control Tools and Techniques | Quality Control
- Run Charts
- Pareto Charts
- Flow Charts
- Scatter Diagrams
- Cause and Effect Diagrams
- Control Charts
- Define Categories for Data
- Collect Data, sort them into the categories
- Count the Data for each category
- Draw the Diagram. Each category finds its place on the x-Axis.
- The bars will be as high as the value for the category
- Centering of the process data: The centering of the data provides information on the process about some mean.
- Spread of the data: Histogram width defines the variability of the process about the mean
- Shape of the histogram: Bell or normal shaped histogram is expected. Other than normal or bell shape means something wrong with the process responsible for poor quality.
- The randomness in the data in developing histogram losses the vital information
- As data are not represented in order, the time-dependent or time-related trends in the process may not be revealed.
2) Run Chart
- Arrange data with time sequence
- Plot the data in order
- Interpreting Data
The run chart reveals the following about the process
- Run charts display process performance over time
- Trends, cycles, and large variations are clearly visible
- An average line may be added to a run chart to clarify movement of the data away from the process average
3) Pareto Chart
A Perot chart is similar like histogram.
- First define categories
- Sort the data into the Categories and find out the
- frequency of occurrence of each category
- Arrange the categories in descending order
4) Flow Chart
- Determine the Process need to be represented by flow chart
- List down the sequence of operation and other details
- Start at a certain point and go then step by step
- Using flow chart symbols
- Write the titles to each element
5) Scatter Diagram
Steps in making Scatter Diagram
- Plot the data points
- Draw trend line by fitting a straight line
- Upward line shows the positive trend(X increases and Y increases)
- Downward line shows the negative trend (X increases and Y decreases)
6) Cause and Effect Diagrams.
Steps in making Cause and Effect Diagram
- Determine the Effect or Problem
- Categorize the possible causes
- Describe the possible causes
7) Control Chart
Steps in making control chart
- Define Upper limit, lower limit and Center line
- Draw Chart
- Plot the data points into chart
- Interpret the control chart
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