Cp Formula

Cp stands for Process capability. It is used to find the measurable property of a process to the width of the specification. The final solution of the process capability is generally specified either in the form of calculations or histograms
\[\LARGE Cp=\frac{USL – LSL}{6\times\sigma}\]
USL is the upper specification limit
LSL is the lower specification limit and
\(\begin{array}{l}\sigma\end{array} \)
is the standard deviation.

Solved Examples

Question 1: Calculate Cp whose USL, LSL and

\(\begin{array}{l}\sigma\end{array} \)
are 10, 6 and 3 respectively?


From the equation, it is given that
USL = 10, LSL = 6 and
\(\begin{array}{l}\sigma\end{array} \)
= 3
Formula for Cp is,
Cp =
\(\begin{array}{l}\frac{USL-LSL}{6\times\sigma}\end{array} \)
Cp =
\(\begin{array}{l}\frac{10-6}{6\times3}\end{array} \)
Cp = 0.222

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