bonding/gluing aluminum

A

alinwa

oft dis'd member
I'll try this again..... I ripped out my windows key and control key and now she's typing away merrily...

SO ANYWAYS!!!!

I've been epoxying AL together using a variety of degreasers, etchants, painting preparations and belt sanding to expose new metal and haven't had great bonding success

I'm currently trying RockSett, just clamped the pieces and am letting it set til tomorrow.

I'll probably next try green Loctite next

then contact adhesive

Anyone have a product or method which will bond AL??
 
Marine-Tex grey has worked well for me. It was designed for boat repairs. Besides using it for bedding rifles, I have fixed aluminum fuel tanks and outboard lower units with it.
 
Well, Rocksett was an absolute failure...... and Marine Tex and JB acted just like AcraGlas

I done ordered me some GM 5200 and am trying Loctite Green......

Then contact adhesive. The hardest thing about the contact cement is alignment. Whooeyyy, scary stuff!

I hope one of the juices works because soldering/brazing/welding are not options
 
I bonded a plate to the deck of a boat with 3M 5200. When I tried to remove the plate a year later some of the deck came up with the plate. The only way to separate anything bonded together with 5200 is to get a length of piano wire attached to two makeshift handles and get the wire between the two parts and use a sawing action to separate them. I have added to the old saying that the only thing that is forever is death, taxes and 5200.
 
tested the full-term epoxies today.......failed

contact cement is wikkid good in tests but too scary to use for effect except as a last resort.

Still waiting for Brown to deliver my magical 5200 elixir

Meanwhile I spake with my son who set up and ran a development lab for SAPA Aluminum a few yrs back and he said "no dice, compressive mechanical fastening and a non-brittle bonding agent for increased slippage coefficient"

So I'm setting my hopes on 5200 being just that!
 
Trick is to prep they alloy properly. What you really need is to "Key" the surface of the alloy in the area you want to bond.. Belt sanding or similar is a pretty poor "key". By far the best is to grit blast the surfaces with a sharp grit like garnet or something similar (not glass beads!). This creates a chemically "activated" surface that will bond chemically. You have about an hour after blasting to get it bonded or the surface looses it's "activation"..

Dan Gelbart give a good explanation in this video..


Cheers
Lee
 
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We grit blasted a spot about 1.1 inch x 1.1 inch to attach a
1.0 inch x 1.0 inch cable tie anchor.
We had little patches to stick down and then blasted at 90
degrees for few seconds.
Use a single edge razor blade to remove the 'frame.'
The strength of every batch of epoxy was tested to verify
content (equal resin and hardener by volume) and mixing
adequacy.
The lat thing you want to happen at 70,000 ft is a cable
bond failing.
The pilots would hear the cable or its connectors flapping
around and abort the flight.
 
WOW! Now we're making progress, thanks guys....... I've been sanding for "tooth" I'll start by garnet blasting fer starters....
 
DUDE!!!!

Leeroy the tip about diamond coated windows is HAPPENING in my shop within the week!

I LOVE videos from guys like this....

THANK YOU!
 
Al

Yes that entire series of videos from Dan is well worth a watch.
One other tip is to make sure your grit blaster is fed with clean dry air. Air that has water vapor will also carry oils from the compressor and can contaminate the blasted finish..

Cheers
Lee
 
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Leeroy said:
Al

Yes that entire series of videos from Dan is well worth a watch.
One other tip is to make sure your grit blaster is fed with clean dry air. Air that has water vapor will also carry oils from the compressor and can contaminate the blasted finish..

Cheers
Lee
Click to expand...

The convenience of an air borne industrial setting and dry ice water vapor removal is not to be underestimated.
We used enough compressed air daily to justify the delivery of 100 pounds of dry ice.
Two 10 in. x 10in. x 10 in. cubes.
They went in very large tank after being generously broken up.
The sublimation temperature is -109F at 14.7 PSI.

Higher (less negative) at higher pressure.
For very critical work we used stainless steel wool in a dry ice at room temp setup.
A bowl of dry ice surrounded the glass bowl of stainless steel.
This allowed for around -109 C to remove remaining moisture.
Dry ice at 14.7 PSI, stainless steel at closer to -109 C.
You needed to be VERY careful squirting the air at exposed flesh, or holding a
smaller object that could quickly be reduced to -109C.
It produced almost instant frosting and 'burn' on the surface.

In the field we relied on 3M non-woven abrasives and operator training for a
correctly scratched surface.
For larger cables we often added a rivet after the epoxy set.
If you riveted with unset epoxy the 'glue line' was weakened by inadequate epoxy between the surfaces.
Set it up, then apply the rivet for extra margin worked well.
Single sided aircraft rivets are a 'grown up' version of a pop rivet.

https://www.amazon.com/Flange-Rivet...-bin:19044840011&s=industrial&sr=1-10-catcorr

A whopper of a URL. Sorry

Heating smaller items (and small is dependent of the oven size) improves epoxy cure.
We had a few 3 ft x 3 ft x 9 ft ovens.
Much smaller items can benefit by preheating before applying epoxy.
 
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3M 3200 is much stronger than epoxy. It held more weight than epoxy and when the joint failed after 23hrs @ 65* it was still tacky inside. As in EVERYTHING more than 1/8" in from the edges was sticky so..... #1, full cure is listed at 48hrs average @ room temperature...... and #2 I'ma try it with heated parts in a heated box and I'm convinced that this stuff will hold! An 1/8" bead around the edges resisted better than fully cured epoxy in which the epoxy separated on my epoxy test.... it separated leaving discernable residue on both surfaces.
 
Mine should be here tomorrow...

alinwa said:
3M 3200 is much stronger than epoxy. It held more weight than epoxy and when the joint failed after 23hrs @ 65* it was still tacky inside. As in EVERYTHING more than 1/8" in from the edges was sticky so..... #1, full cure is listed at 48hrs average @ room temperature...... and #2 I'ma try it with heated parts in a heated box and I'm convinced that this stuff will hold! An 1/8" bead around the edges resisted better than fully cured epoxy in which the epoxy separated on my epoxy test.... it separated leaving discernable residue on both surfaces.
Click to expand...

I don't actually have an immediate need, but I was so enthralled that I had to try some... I'm going to compare it to PC-11 (Marine version of "PC-7" - and my go-to GP epoxy), we'll see...

GsT

BTW, Another thanks to Lee for the D. Gelbart videos. I'd seen his precision lathe before, but hadn't been back and he's apparently done a lot of cool stuff since then!
 
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