Gluing Lots of Aluminium

[drawoh]

Does anybody here use epoxy or cyanoacrylate to bond aluminium in a production process? I am looking through websites and videos on surface preparation, and I would like to know how this works on a production line with semi-trained workers on lots of parts, rapidly, of course.

--
JHG

 

[MintJulep]

Generally I would expect it to work poorly.

Good stuff to think about and read. thread2-278458

 

[Compositepro]

Aluminum aircraft use a lot of adhesive bonding. Surface treatment and process quality control are essential. CAA (chromic acid anodize) and PPA (using phosphoric acid) are commonly used.

Applications like boats, automotive, and RV's will use very flexible (acrylic) adhesives and thick bondlines, which are very lightly loaded, and failures are not sudden and catastrophic. You need to speak with adhesive suppliers who will recommend the best one for your end use as well as your manufacturing process.

 

[blakmax]

I agree with Mint Julep. Read the discussion at that link. Then realise that if you test using shear strength or even peel strength tests you are going to get a false impression that your process gives you good strength. It may do in the short term but long term there will probably be a rash of disbonds. I suggest you try the wedge test ASTM D3762, but read DOT/FAA/AR – TN06/57, May 2007 for acceptance criteria. Adhesive bonds to aluminium involve the formation of ionic and covalent bonds with the oxides produced during surface preparation at the surface of the metal. These oxides have an affinity for the formation of hydrated oxides when exposed to humidity. For the oxides to hydrate, the chemical bonds formed at the time of bonding must dissociate, thus leading to disbonding. This is why strength tests do not prove the adequacy of surface preparation processes. The secret to success is to treat the surface at the time of preparation to prevent that hydration. Please note that hydration related failures can be totally independent of loads, so don't think that just because loads are low that surface preparation is not needed. Doubling the overlap to account for bad processing will simply result in twice the size of disbond.

Regards

Blakmax