B) Description of the process position215 Focus: Process position -> hence the designation "position index"216 With mean shifts (to the left or to the right), the Cpk value becomes less than 1 if half the manufacturing variation (3s) is greater than the min. distance.217 If the process mean value moves beyond the tolerance limits, the Cpk value becomes a negative number.218 If the min. distance is equal to half the process variation (3s), the Cpk value is equal to 1.219 If the mean value of the manufacturing process is optimum, i.e. set precisely at the centre of the tolerance field, the Cpk value is equal to the Cp value and ≥ 1.220 A Cpk value of >1.5 means it is (almost) possible to drive in (manufacture) blind.