For a given item the upper specification limit is 65 and the lower specification limit is 43. It can be assumed that: 1) the process mean is centered in the specification interval; and 2) the process standard deviation is 4.4. What is this process’ capability ratio?
Expert Answer
USL=65
LSL =43
Mean ,U=(65+43)/2=54
Std Dev = 4.4
Cpk=min (CpU,CpL)
CpU= (USL-Mean)/(3*std dev) = 11/(3*4.4)= 0.833
CpL= (Mean-LSL)/(3*Std Dev) = 0.833
Hence, Cpk= 0.833