Loctite release

[Gordon]

I made a cylinder liner and pressed it into the cylinder using Loctite #638. There are holes through the cylinder and through the liner. Before drilling through the liner I tested it and there is free air flow so the liner is not sealed in the cylinder. My question is what temperature must I heat the assembly to in order to release the liner and does it have to be hot in order to be released? I heated it up to 400° in the toaster oven and it has not released.

 

[Jasonb]

nearer 500deg, see top of page 3

https://datasheets.tdx.henkel.com/LOCTITE-638-en_GL.pdf

 

[Gordon]

Thanks. I assume that the Loctite was wiped off when I inserted it. Any suggestions on what Loctite I should be using? I assume something that is wicking.

 

[Jasonb]

I tend to use 648

 

[Ken I]

Locktite give recommended clearances - see the spec. sheets.
We once had a production problem with locktited parts coming loose in the field - traced to an overzealous draughtsman who felt that the clearance was overly large and tightened it up without clearing it with anybody.
If you want a press fit liner you cannot locktite the press fit zone to any great effect - if you are trying to seal some part of the liner you will need enough clearance there. You might try injecting the locktite at the holes in question. Don't leave a syringe full of locktite - it will go solid.
As regards degradation temperature - I just heat it until smoke comes off - as far as my experience goes it has never been hot enough to do any harm to steel or aluminium etc.
But being careful with precious work is always prudent.
Regards, Ken I

 

[Vietti]

I have had very good luck sealing leaking valve cages with the wicking thread locking locktite. Someone suggested it a while back and it works very well. In fact this stuff wicks so agressively you need to be careful it doesn't lock up something you would rather not lock! Try it!!

 

[Vietti]

Product is Locktite 290-try it, nothing to loose at this point.

 

[petertha]

A couple more points to add

- is the cylinder material expanding at a higher rate than the liner material, or the other way around? I understand the intent is to fail the adhesive, but the 2 metals are going along for the temperature ride. If the liners are expanding at a higher rate than cylinder, its obviously not helping.

- I made some test cylinders from 6061 aluminum with CI liners. No adhesive just different degrees of what I thought minimal interference. Dropping the room temp liner into heated cylinder was easy. One would think with the relative temp coefficients the aluminum would expand much more & disassembly would be easy. It put up a fight. What I chock this up to is is the expansion math doesn't factor the reality of micro machining marks from turning. Think of them as as threads. So thermal expansion has to additionally overcome the hills wherever they may be 'nested'. My cylinder ID was reamed & my liner OD was lapped, but even so, quite amazing how a bit of interference can lock thinks up pretty tight.

Anyway, good luck. Keep us posted