Glue or weld?

[robwizard]

I have heard off some adhesives (not glue..?) being used in the automotive and aerospace industry to hold aluminum together, allegedly stronger than welding it. After reading a bit about it I can understand how it makes sense, with the area of adhesion being larger than that of a weld and how the material incurs no damage from the heat etc..

But what about a butt weld? Say.. on a car body repair or something?

I have no intention of doing this, I am currently learning to weld aluminum and loving it I'm just curious what people think?

Cheers

 

[Hitch]

The thing with some adhesives is in a straight pull situation they can be quite strong, introduce twisting movements or shock and they can fail much easier, depending on the adhesive.

Used to build ally security cabinet things with most of it glued together, think it was 3m scotch weld something or another, great stuff, as long as you followed the instructions.
Smarm it on and hope for the best, and it would fall apart in your hand.

If they specify primers/etch solutions, its a must to use them.

 

[outofthefire]

I must admit I can't get used to the idea of glue being that strong, but like you say its used in the auto and air industry. We bond wind deflectors on some wagons and so long as the parts have been cleaned and degreased they don't come off.

 

[tigler]

Much depends on the design of a given structure.
Where used in aviation the structure is designed to be built using adhesive. So the joint will have large surfaces in contact which allows the adhesive to create a bond over a large area. So the cumulative strength is proportional to the unit area. Also the direction that forces applied to the structure act in is important. Bonding edge to edge wouldn't work with adhesive as there is too little surface area.

 

[Hotmetal]

You could bond it edge to edge if you bond a butt strap behind the joint.

 

[pedrobedro]

You could bond it edge to edge if you bond a butt strap behind the joint.

Is he allowed to say butt strap, it is a family forum
Epoxy adhesives are used in the construction of bridges and Lotus Elise chassis are held together with rivets plus adhesive and there are non welded panel adhesives available. As above, it's all dependent on the job and the preparation.

 

[graffian]

Is he allowed to say butt strap, it is a family forum

if it's a tube bond a butt plug in.

 

[J_K]

I use this stuff for bonding low surface energy plastic together (PE, ABS etc)
http://solutions.3m.com/wps/portal/...ECIE20S4K7000000_nid=LS56XTRKJXbeQH8HT14PGTgl
And it is unreal.
I read the spec and it says Aluminium can also be bonded so used some to reinforce the bottom of a plastic drum.
That particular fix failed but it actually tore parts of the PE drum off rather than being a failure of the adhesive.
It's £17 a tube and you have to use the £40 3M gun to apply it but it is incredible stuff.

 

[MrFluffy]

I have just ordered a load of structural adhesive to do some modifications to the crankcase on one of my bikes, but I do admit the oldschool part of my brain wants to do a tack here and there to make sure. Looking at adhesive because of distortion creating loads of problems post weld with bearing locations etc.
As part of my research I spoke to a friend who does something rather specialised in industry, and he said there are even stronger adhesives available to special order, but they have a very limited shelf life (weeks from manufacture) therefore not available to the wider public. If anyone finds a supplier of such or the part number I'd be interested...

 

[cardiffrob]

If you can cut a 15:1 angle through plywood you can glue sheets together. Modern adhesives are very good but, typically, not approved in the UK.


PS That is 5 ply and just 2.3mm thick. You carve the edges down with a Stanley Knife blade.

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