Press Fit vs. Shrink Fit
Press Fit vs. Shrink Fit
(OP)
Hello everyone. This is my first post, so bear with me.
My project involves fitting a solid shaft of Beryllium Copper (BeCu) into a BeCu sleeve. I am trying to figure you the best method to do so. My calculations are a bit rusty so I am not sure if I have done this correctly. I suppose the best way to compare the 2 methods is to see which one has lesser stress and less radial expansion.
I have computed the stress in the press fit by using the following formula (from engineeringtoolbox.com)
sr = abs((((a)^2*p)/(b^2 - a^2))*(1 - (b^2 / r^2)));
Sorry for the raw Matlab code. If it is easier, please view the formula @ http://ww w.engineer ingtoolbox .com/stres s-thick-wa lled-tube- d_949.html
I computed the radial stress (Sr) for the shrinkage fit by using the formula found @ http://www.ameritherm.com/PDFs/shrinkfitcalcs.pdf
With both stresses, I simply used Hooke's Formula (sigma=E*epsilon) to find the radial deformation.
It seems that the shrink fit causes higher stress and deformation. Thoughts?
Thank you!
My project involves fitting a solid shaft of Beryllium Copper (BeCu) into a BeCu sleeve. I am trying to figure you the best method to do so. My calculations are a bit rusty so I am not sure if I have done this correctly. I suppose the best way to compare the 2 methods is to see which one has lesser stress and less radial expansion.
I have computed the stress in the press fit by using the following formula (from engineeringtoolbox.com)
sr = abs((((a)^2*p)/(b^2 - a^2))*(1 - (b^2 / r^2)));
Sorry for the raw Matlab code. If it is easier, please view the formula @ http://ww
I computed the radial stress (Sr) for the shrinkage fit by using the formula found @ http://www.ameritherm.com/PDFs/shrinkfitcalcs.pdf
With both stresses, I simply used Hooke's Formula (sigma=E*epsilon) to find the radial deformation.
It seems that the shrink fit causes higher stress and deformation. Thoughts?
Thank you!





RE: Press Fit vs. Shrink Fit
You need to get a hold of a mechanical design book such as from Shigley or Norton or Machinery's Handbook.
Do a search in this site, the issue is already posted many times.
RE: Press Fit vs. Shrink Fit
After that, I need to find the total deformation AKA the new outside diameter of the Hub. Also, I have Machinery's handbook, but is a bit vague in this area.
Thank you
RE: Press Fit vs. Shrink Fit
It's hard to give direct answers when we do not know the design details. But I would break this down into parts:
1. How this tube functions in the assembly.
2. The interfaces sleeve, shaft and Bore.
3. Static stresses
4. Dynamic stresses
5. finish the list because I am going home :)
Heckler
Sr. Mechanical Engineer
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RE: Press Fit vs. Shrink Fit
Ok, so I found the load required to fit this to be 2.03 tons. I also found the contact pressure to be 12550 psi. Now I need to check to make sure the BeCu is not yielding (i'm sure it isnt, but I need to show proof). I think I will use a pressure vessel setup to find the radial and circumfrential stresses then check to make sure they are below the Yield strength for BeCu.
Also, this pressed assembly will not be rotating.
RE: Press Fit vs. Shrink Fit