Bonding Aluminum

jcarleto

Aluminum Supporter
Joined
Jun 5, 2007
Messages
3,571
Location
Taylorsville, GA
Aircraft
Beech Bonanza G-35 N4638D/"The Bulldozer" 2-Place Gyroplane N575EE
Total Flight Time
Several
I am building a new keel for the "Bulldozer" and want to use the Parsons design using 3 pieces of 1" x 2" x 1/4" 6061-T6 rectangular tubing in a "two up, one flat" configuration, yielding a 2" x 3" finished keel. I want to bond the 3 pieces.

What is the preferred adhesive and surface treatment process these days to get a reliable bond? Sources for the required ingredients would also be a great help.

Thanks!
 
Jon I am not saying my method is bullet proof so here is what I did. Cleaned up the two pieces to be bonded the best you can (degrease them blah blah blah) Mix up the bonding agent. (in my case I just used regular J&B weld) Apply a thin layer on the surfaces. Grab a clean (not greasy) wire brush and with circular motion go over the whole length. The wire brush should remove the oxidized surface and the bonding agent will shield it from the air getting to it. Adhere the two pieces and clamp the crap out of them so you end up with the thinnest possible bonding agent between the pieces. :)
 
Hey Jon, the strongest product Ive found is PR1440 B1/2 fuel tank sealant, from Flamemaster Chem Seal. Slightly pliable when cured, resistant to anything. I agree with the Alodine preperation. Cures overnight, cleans up with acetone, while wet. Mike.
 
Gabor, I'm assuming you mean a brass bristle brush and not a steel wire brush.

You should never use a steel wire brush on aluminum.
 
Chuck yes I did use the brass wire. I wouldn't dare to use steel LOL. I had one of these smaller kinds that are only 6-7 inches long and if you use it once that's pretty much all it can take anyways. :)
 
I'm a big fan of 2 part methyl methacrylate glue. I find that it bonds stronger than epoxy and is much less sensitive to how clean the parts are. In my tests it was stronger than epoxy when you glued it without prepping it at all compared to bonding with epoxy that was sanded and washed with either acetone or alcohol. I didn't compare it to epoxy prepped like Chuck recommends.
 
Speaking of brushing aluminum, there was at one time a commercially available tool for soldering aluminum with ordinary lead/tin solder. It had a brush on its tip driven ultrasonically. The brush scrubbed off the oxide while shielded by the solder puddle.
 
Thanks all,

I have used alodine in the past with good results. It never hurts to check and see if something else has surfaced in the mean time.

Methacrylate is good stuff too, but I have far more experience with epoxies. I think I'll "go with what I know."
 
Why cant you use a steel wire brush on aluminum?
 
it will impregnate the aluminum with carbon for one thing and it will rust, not sure what else it does. Dont use steel brushes on stainless for that reason as well.
 
Grant the still brush will create a much deeper scratch into the surface of the AL than needed. We only want to remove the oxidation and the brass soft bristle is plenty enough, we are not trying to roughen the surface.
 
dinoa said:
Read this extensive thread especially posts 62,146 and 165. If you have time read all posts written by "MalcomW" and "blackmax". It is time well spent if you are considering bonding structural aluminum.

http://www.homebuiltairplanes.com/fo...-tests-10.html
Interesting read. I lived in South Florida for a while and know there is no real way to permanently avoid corrosion in sea coast environment. Fortunately, though the humidity can get high here, I am far from the sea and it's corrosion problems.

Perhaps I should have said that I will be bonding the aluminum in addition to the normal array of clamps and bolts and things. My best hope is additional strength to beef up the structure which may already be strong enough without help.
 
GrantR :
When I have to weld aluminum at work I have to use a special grinding disc to clean it up or the weld will not hold... If I use a steel wire brush it leave some kind of stuff on the aluminum and I don't get a clean weld.... I have tried the acid that you put on aluminum to clean it up and even when I use this it still doesn't do as good as the grinder.
 
For bonding aluminum the industry standard surface prep is phosphoric acid etch as per BAC 5555 or ASTM D 3933. Because the process is difficult to perform for field repairs Boeing developed a product called Boegel which it licensed out and is now sold as AC330 which you can get from Pacific Coast Composites. It is expensive.

That said, in a previous thread http://www.rotaryforum.com/forum/showthread.php?t=15460

these products were mentioned:

3M Scotchweld 2216BA

and Hysol E-20NS

I looked at the data sheets for the 3M product and it says you can use it after scuffing or grit blasting the surface. 3M is a big reputable company aware of product liability and it should stand by its claim. So this presents a conflict. On the one hand consultants and others insisting that surface priming is mandatory (homebuilt forum) and on the other 3M. Take your pick.


Dino
 
We have been using Dow Corning Z6040 bonding agent with fine grit blasted surface and solvent degreased, this is not on aircraft at present but is on a ducted fan in salt water running hard, so far so good, looking at how we can fix the edge of erosion strips that come undone surprisingly quickly on helio blades, the process will work as suggested, the cleaning\removal of corrosion between strip & blade is the problem
This was a BM recommendation it stopped the separation we had with previous de grease & scuff:humble:
 
500e,


That's interesting. Silane is one of the ingredients in Boegel and AC330 and has been used with good results to prep aluminum for bonding as reported in the homebuilders forum. Silane is primarilly used to "size" glass fibers so they adhere to resins.

Could you post a source for Dow Corning Z6040.


Dino
 
GBA sent Magnolia 6155 in the SH kit as a structural adhesive for the tail section. They have the builder bond the composite skin to the aluminum tube and the aluminum center support inside the tube spar. I cleaned with solvent and then used a Scotch bright pad to remove oxidation just prior to the bond.
 
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