Cp and Cpk

Cp

Cp compares spec width with six-sigma width.

highlighted = computed this step

Spec Width

Spec width is upper spec minus lower spec.

60−40=2060 - 40 = 20
WidthsThe table recomputes spec width, six-sigma width, and Cp.width comparisonvaluespec width20six-sigma width12Cp5/3

Six-Sigma Width

Six-sigma width is six times sigma.

6×2=126\times2 = 12
WidthsThe table recomputes spec width, six-sigma width, and Cp.width comparisonvaluespec width20six-sigma width12Cp5/3

Cp

Cp is 5/3.

20/12=5/320 / 12 = 5/3
WidthsThe table recomputes spec width, six-sigma width, and Cp.width comparisonvaluespec width20six-sigma width12Cp5/3