thermal expansion shrink fit 1

[Mattberghofttt]

Need to find formula for calculating the temperature for shrink fitting a .250 steel shaft into a .2485 diameter hole.
Does any one know a formula for finding the temerature increase of this hole.

 

[Co]

Have you checked a machinery's handbook?
The very practical method presented is in general given by a linear expansion coefficient of the metal.
For steel it is given as: 6.5(10^-6).
An example given: outer member of steel expanded 0.005 inch per inch of internal diameter. Then,

t=0.005/0.0000065=769.23 deg. F

Don't forget to add an allowance for clearance.

cheers,

 

[Mattberghofttt]

Does the size of the part matter in this specific calculation?
In other words if I were to increase the diameter by 2 inches in diameter on the hole and the shaft would the amount of material to be heated make a difference for the total temperature calculated?

 

[Co]

I suppose in theory the temperature would not be affected by the size. In order to heat up the larger volume of steel you will need more heat flux or a lot more time. Thus, I can say again from this linear expansion coefficient that if you use it correctly then you are safe.
Don't forget that the number given in the above example (0.005) is dependent on the percentage of the diameter that you want to increase not necessarily the size.

 

[chicopee]

Mechanical engineering handbooks have good material on shrink and interference fits.