Process Capability (Cp)
Definition
A measure of process potential capability, calculated as Cp = (USL - LSL) / (6σ). It compares the specification width to the process spread, assuming the process is centered. Cp only measures spread, not centering.
Practical Note
Cp ≥ 1.33 is typically acceptable. Cp = 1.0 means the process spread exactly equals the spec width (3σ on each side). Cp ignores process centering - use Cpk for actual capability.