Two parts are to be joined together using the Expansion Fit

Two parts are to be joined together using the Expansion Fit Process. The material which will be heated is Carbon Steel and the coefficient of linear expansion is in the middle of the range. The pin will be cooled to -400 F and nominal diameter (D1) is 0.6875”. With a starting temperature of 68 F, what would the pin diameter need to be to allow for a 20% clearance under the conditions stated for a good fit when assembling?

Solution

Solution:

initial temp is 68F

final temp is -400 F

temp difference T is 468 F

For carbon steel linear expansion K is 0.0000068 in/(in F)

d is 0.6875 inch

Shrinkage/Expansion is given by E = T K d

= 0.0021879

Reduction in size of diameter will be = 0.0021879 (0.6875)

= 0.0015

Final diameter will be given by = 0.6859 in

with 20% clerance pin diameter will become = 0.6859-(0.2)(0.6859)

= 0.5487 in