Types of control chart for variables - Metrology & Quality Control

Discussion

• Sravanthi   -Posted on 27 Oct 15
  - A statistical technique used for controlling quality of products is known as a control chart.
  
  - The different types of quality control charts are:
  
  1) Control by variables:
  a) X chart
  b) R chart
  
  2) Control by attributes:
  a) P chart
  b) nP chart
  c) C chart
  d) U chart
  
  - Control charts for variables:
  
  - Quality control charts for variables such as X chart and R chart are used to study the distribution of measured data.
  
  - X chart is plotted by calculating upper and lower deviations.
  
  Upper control limit and lower control limit for X chart
  are calculated using the formula:
  
  (UCL)_X = x̿ + 3 σ_X
  
  (LCL)_X = x̿ - 3 σ_X
  
  Here, X = Mean value of measurements of a particular sample
  
  - R chart is used for distributing the measured data.
  
  
  Note:
  x̿ = X-Double bar
  

➨ Post your comment / Share knowledge