Suppose it is desired to establish the relationship between nominal dimensions o
ID: 454733 • Letter: S
Question
Suppose it is desired to establish the relationship between nominal dimensions of extension and sockets on hand tools in a situation similar to example presented in the lecture but involving different size. Assume that a study of consumer requirements indicated a desirable minimum clearance of 0.005 inch and a maximum clearance of 0.018 inch. Assume that a study of past production showed an average dimension of extension of 0.7510 with a standard deviation of 0.0015 and an average dimension of sockets of 0.7650 with a standard deviation of 0.0010. Both distributions are statistically controlled and approximately normal.
If you are asked to optimize the process to minimize the probability of getting undesirable clearance in the assembly, and you are allowed to recenter the process for the extension. What average dimension would you aimed at? (keep 4 decimal places)
Explanation / Answer
Answer:
Here F is for socket and M is for extension
The 3-sigma limits of the extension are = 0.0045
The 3-sigma limits of the extension are = 0.0030
sigma( F-M) = sqrt((0.0015)2 + (0.0001)2) = SQRT(0.00000225 + 0.000001) = 0.00180278
XF - XM = 0.7650 - 0.7510 = 0.014
The maximum clearence limit is 0.018 there fore the average dimension is 0.014