A metal-cutting operation has a target value of 20 and consistently averages 19.8 with a standard deviation of 0.5.The design engineers have established an upper specification limit of 22 and a lower specification limit of 18.What is the process capability ratio?
A)1.20
B)1.33
C)1.46
D)1.66

Question

Quizplus · Accepted Answer

The process capability ratio is calculated by dividing the allowable tolerance or specification limits by the process variation. Therefore, in this case, the allowable tolerance is the difference between the upper and lower specification limits, which is 22 - 18 = 4. The process variation is given by the standard deviation, which is 0.5.

Process capability ratio = (upper specification limit - lower specification limit) / (6 * standard deviation)
= (22 - 18) / (6 * 0.5)
= 4 / 3
= 1.33

Therefore, the correct choice is B.

A Metal-Cutting Operation Has a Target Value of 20 and Consistently