Lean Definition

CPK

CPK is a Statistical calculation used to indicate how well a design tolerance compares with the normal process variation ( defined as +/-3s) and accounts for any difference between the design target and the actual process mean. A good CPK indicates that the process is consistently under control- i.e within specification limits –and is also centred on the design target value. A CPK value of 1.33 is typically considered a minimum acceptable process capability; as the CPK value approaches 1.5, The process approaches six sigma capability (3.4 defective units per million).