I have long been of the opinion that, if you have to rely on glue for attaching something to aluminum, you should rethink your design.
I am changing my mind.
A little over a year ago, an artist friend of mine asked me to help her out.
She had been having photographs printed large (24"x32"), having them mounted to a sheet of aluminum. and attaching a frame made of 1" sq alum tube to the back to act as a stand off when hung on a wall.
The outfit she had been using in Milwaukee to do the work, got shut down on an OSHA beef and she wanted me to do the final assembly.
She tells me she has that she has bought the special glue and dispenser that they were using.
"Wait a minute!" I sez, "Aluminum and glue don't mix"
But somebody else has already done it and this isn't a life safety application. So, I call an engineer at Lord Adhesives to ask him about application techniques.
I ask him if I have to sand the metal, or etch, or use some special primer, and he sez "No,".
"This stuff is specially designed to work with dirty metal. That's why it works well on aluminum. You don't need any special surface prep. You don't want chunks of dirt or dripping oil, but finger prints and light oxides are not a problem."
Well it worked a treat.
Months later I have another aluminum job. This one needs me to rivet the short edge of some 1/2"x 1.25" anodized alum glass channel to 6 ft long
1.75" anodized aluminum angles. The channels are attached perpendicular to the angle and I used the adhesive to glue them temporarily to the angle while I drilled the rivet holes.
There was only a 1/2"x1" glue surface on each one (2 per angle, 144 angles) but despite rough handling not a single one got knocked off.
Last week I had another aluminum job.
A small museum without a lot of money, needs some stands made. After talking the designer out of some grandiose ideas, I point to the aluminum angle falloff from the other job, and say, "I can make you some out of that real cheap.".
The design we ended up with was a bunch of simple, flat, angle frames about
16" square.
The corners were simple lap joints with a short piece of angle mounted in the inside of the corners to act as a gusset.
I figured that I would glue it and rivet it like the other assembly. but, when the glue was set, the joints were so strong that the rivets were a waste if time.
I did some more research and this glue has a shear strength of 475 psi. That means each glued corner has roughly the same strength as if it were put together with 16 standard strength 1/8" solid alum rivets. I have a spare frame here, that I have been sitting on and rocking back and forth. The angle flexes, but no sign of glue failure.
Anyway, this stuff was Lord #406-19, a two part acrylic adhesive. It costs about $13 bucks a tube and because of a 4-1 mix ratio you need a special glue dispensing gun.
I am not affiliated with the company, just an impressed consumer.
Paul K. Dickman