BONDING ALUMINIUM THREADED SLEEVE INTO A HOUSING OF ALUMINIUM 1

[roberto1brazil]

Hello everybody, please could someone help me with the following issue?
At our shop floor we had to bond a solid sleeve of aluminium with an external thread of M8 x 1,0 mm into a housing of an aluminium casing . The total depth is 26 mm – the same dimension as the sleeve length.
The parts were cleaned before bonding. The casing is cleaned with alkaline degreasing chemical product and the sleeve degreased using hydrocarbon solvents. Before applying the bond, the sleeve was tested inside its housing and it fitted without problems.
The procedure to bonding:
We use Araldite 2014 –Apply the adhesive to 2 or 3 threads of the sleeve.
Do an assembly and then a disassembly of the sleeve.
Remove the excess of adhesive from the sleeve end.
Make sure the adhesive film is applied on all the threads.
(*)Put the sleeve in position and tighten.
Remove the excess of adhesive around the sleeve.
Stove the intermediate body at 90°C for 1 h.

The problem : When putting the sleeve in position (step *) , it made hard gotten jammed and did not move (turn) any more. At that time the sleeve was in the middle of the course. We had to cut the sleeve and drilled its core to remove it. Please, have you an idea what had happened to griping the sleeve so fast?
Thanks
Roberto

 

[desertfox]

Hi roberto1brazil

I suggest you talk to the adhesive people.

desertfox

 

[CoryPad]

Your adhesive is a paste which likely is too thick for the small allowance of your fine pitch thread. You should try using a threadlocker such as 3M's Scotch-Weld or one of the Loctite anaerobic products.

 

[MikeHalloran]

From the Huntsman data sheet:
"The joint components should be assembled and secured in a fixed position as soon as the adhesive has been applied."

There is no mention of anything like:
"Do an assembly and then a disassembly of the sleeve. "

If you're not going to follow the adhesive manufacturer's instructions, do not expect to achieve their reported results.

If the assemble/disassemble/assemble sequence was the result of an unsuccessful attempt to use the proper sequence, it was clearly the wrong tactic to solve whatever problem was encountered.

Maybe you need different clearances as noted or different adhesive, but you clearly need a different procedure.





Mike Halloran
Pembroke Pines, FL, USA

 

[roberto1brazil]

Thanks all of you for the information. We will try another procedure as advised. The adhesive cannot be changed because it is mentioned in our internal specification. Anyway, I believe that it is possible to develop other ways.
Regards
Roberto

 

[Tmoose]

Did the plug "jam" because the epoxy set up, or because the aluminum parts galled and seized? Is the seizing a random event, or happens every time so far?

Some Araldite 2014 literature says a pot life of ~80 minutes.

http://krayden.com/tds/hunts_araldite_2014_tds.pdf

What is the class/quality of the threads in and on the parts? More clearance might make for easier assembly.

Dan T

 

[roberto1brazil]

Hi Dan

At our company we had done some similar tasks before but not with a so fine thread. For this kind of thread it was the first time. I believe that the "jam" was caused by the epoxy set up because, I had said before, the parts were cleaned and tested its fitting (without the adhesive) with no problems. At next time we are going to do it with less adhesive and having a clearance little more opened.
Thanks for the attention.
Roberto

 

[Tmoose]

Hi Roberto,

when I read your procedure I took it to mean one trial fitting before degreasing, and trial after degreasing with adhesive applied to a few threads.

I have had parts with clearance fits gall when thoroughly degreased, that would give no assembly problems when tested with parts blown dry, but still carrying the residue of the manufacturing processes.