Gluing Aluminum Parts...?

[Derek Arita]

I know this isn't a metals forum, but I think we all have some experience with metal in our tools, so here goes....
I have some small aluminum plane parts that I need to repair with home made parts. I'm looking for a readily available glue, rather than going to the expense of having them welded together.
I've done some reading online and have seen JB Weld and Loctite Metal used a lot. Thoughts?

[Lee Schierer]

I have had some success adhering metal parts together with PC-7315325

[Bruce Page]

JB Weld. I've also had good results with LePage's metal epoxy.

[Chris Padilla]

Try polyurethane glue...yeah, Gorilla Glue. I'm serious. That stuff darn near can glue anything to anything.

[Mort Stevens]

I've had some experience with gluing metals and can tell you that...

1) JB Weld on aluminum will not stand up to any sheer load. I tried making a thicker sheet out of some thinner material and they just popped apart with very little effort... this was with polished sheets, so I even tried roughing up the surface with the same results... maybe there's a JB Weld specifically for aluminum? But in other applications where it's a compressive load it's fine.

2) Polyurethane glue (Gorilla Glue) has slightly better sheer strength than JB Weld, but needs a large area for any amount of strength in the joint.

I would say if the parts can be welded or brazed that's the way to go.

[Graham Wintersgill]

Pop rivets? Just a thought.

Regards

Graham

[John Coloccia]

I know this isn't a metals forum, but I think we all have some experience with metal in our tools, so here goes....
I have some small aluminum plane parts that I need to repair with home made parts. I'm looking for a readily available glue, rather than going to the expense of having them welded together.
I've done some reading online and have seen JB Weld and Loctite Metal used a lot. Thoughts?

I do have some experience building aluminum airplanes... What parts were you thinking of gluing? Generally speaking, aluminum doesn't glue well.

[Charles Wiggins]

When it comes to metal I have never seen as adhesive that could compete with welding or a mechanical fastener like bolts or rivets.

[Kent A Bathurst]

The classic on-line reference: This to That

http://www.thistothat.com/

Look at Metal to Metal............

[Chris Padilla]

The classic on-line reference: This to That

http://www.thistothat.com/

Look at Metal to Metal............

Wood to Wood has a glue I've never heard of.

[ian maybury]

I guess it depends a bit on what ail be required of the finished parts.

Aluminium actually does bond well with epoxies for example, but only if you can get past the oxide layer, anodising, seal coats, dirt and all the rest. There's a decent write up here: http://www.epotek.com/site/files/Techtips/pdfs/Tech_Tip_24_-_Bonding_to_AL.pdf

That's not going to be easy in the case of a brittle fracture where the break happened some time ago so that the surface has oxidised in contact with the air, and where it's crystalline and hence can't be cleaned with a stainless brush or whatever - where a layer has to be removed from the surface to expose fresh metal before immeditaely bonding it.

No adhesive performs well in a peel test. That's where for example two pieces of thin sheet are glued together and force is then applied to pull the pieces apart at the same end (as when ripping a piece of cloth) - all of the force ends up being fed into the line of adhesive right at the point where the two pieces of metal meet. (the bond line) It unzips with very little force...

Subject to a careful reading of the instructions to verify suitability for the material you have I'd give serious consideration to trying one of the several low temperature aluminium solders that are available now: http://durafix.com They are DIY friendly/relatively easy to use/need only a basic gas torch, and are quite strong - with the key being that they melt at least 100 deg F below the lowest melting point aluminium, and considerably more in the case of most grades.

It'd be best to make up a steel jig that would securely hold the parts precisely in alignment while permitting access for soldering. Maybe look to as above file away a little of the metal at each surface of the break and V it a bit towards the surface in the hope of ensuring that the solder flows easily into the gap.

Best to make a few practice runs on test pieces and get a feel for how it flows before doing your good parts. YouTube and maker's demo videos should give a feel for how it goes. Basics are that total cleanliness and a fresh metal surface are essential, you melt the rod on the heated metal/never directly heat the rod, and the solder will flow where the heat is - so you get control by making sure the heat is where you want the solder to go. Don't overheat the metal, apart from the risk of melting it it could produce an oxide layer that would prevent the solder from wetting out, and need re-prepping of the surfaces to be joined...

[John Coloccia]

I think people have had luck with methacrylate adhesives, presumably because something in there is able to prevent or remove the oxide that forms (practically instantly, I might add). Still, I think corrosion still ends up being a problem without careful process control. Anyhow, I wouldn't trust a glued aluminum piece on an airplane unless it was on something fairly benign....like an emblem.

[Chris Padilla]

It doesn't help you any but when I toured the BMW plant in Dingolfing, Germany, they used some kind of adhesive to glue various metals to various metals. I'm sure those were very very good glues. :)

[Dan Hintz]

Derek,

I know you said no welding, but did you know you can "weld" using nothing more than a propane torch? Find some low-temp aluminum welding rod... no need for a welding machine, and the "weld" you create will be stronger than the two pieces you're sticking together.

[Curt Harms]

I do have some experience building aluminum airplanes... What parts were you thinking of gluing? Generally speaking, aluminum doesn't glue well.

Oh, it does but perhaps not using processes available to we mere mortals. Take a look at a CJ wing. Not many (if any) rivets in the skins. Here's some insight into what's involved: https://www.niar.wichita.edu/niarworkshops/Portals/0/Jun18_0800_JimK.pdf

[ian maybury]

My own experience working on applications development for a mutinational doing high performance engineering adhesives was that there's always the possibility of getting caught by unrecognised process variables that cause an otherwise reliable bonding process to misbehave. Usually by preventing proper wetting and hence good adhesion.

The weakness of adhesives on metals (and in general - compared to mechanical fastenings) is perhaps that it's so hard to get control of all of the variables. The most obscure of factors can pop up in what seemed to be watertight processes - that have maybe worked trouble free for years. A sub contractor makes a small change in the method by which they solvent wash parts for example, or change the process causing a change in the electronegativity of the surface ( a small change or uncontrolled factor in the temperature or gas mix used in brazing for example) or stretch the interval between solvent replacements in a wash tank...