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
$\LARGE Cp=\frac{USL – LSL}{6\times\sigma}$
Where,
USL is the upper specification limit
LSL is the lower specification limit and
$\sigma$ is the standard deviation.

Solved Examples

Question 1: Calculate Cp whose USL, LSL and $\sigma$ are 10, 6 and 3 respectively?

Solution:

From the equation, it is given that
USL = 10, LSL = 6 and $\sigma$ = 3
Formula for Cp is,
Cp = $\frac{USL-LSL}{6\times\sigma}$
Cp = $\frac{10-6}{6\times3}$
Cp = 0.222