short socket interference fit

[subsearobot]

Hello people!
I'm reviewing a design that calls for a small steel shaft to be permanently held in place via a press fit into an ultem socket.
The aspect ratio of the interface is .67 (depth of socket to diameter of shaft)
this item needs to be repeatedly temperature cycled, but otherwise will not experience forces beyond gravity.

I think that over time, the hole will, pardon my terminology, squeeze one out. If so, let's talk about estimating the extrusion force.
any thoughts? I don't want to make undue corrections, but this just seems like a problem waiting to happen, but aside from lots of testing, I don't really have a sense of the risk here.

 

[desertfox]

Hi subsearobot

What’s the temperatures involved and the materials of the components? Also what is the actual interference because that will be extremely important if the joint is temperature cycling.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[subsearobot]

desertfox, dt will be about 100C. it will not come close to the glass transition of the ultem.
I have not done rhe cte study- probly should be next

 

[GregLocock]

Think about glueing the shaft in, not a press fit. Or ideally mould a nutsert into the Ultem and then screw the thing in. What grade Ultem?



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[EdStainless]

Molded in inserts with either grooves or kneraling on the OD would be the usual approach.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed