Brazing Aluminum

[calumc]

sorry bout dat crazy, i was just curious as to what is in these because i have always been told that all you can do with aluminium is weld it with a TIG which is supposedly extremely hard to do (i've never tried)
But i would say to anyone that wants to try this and doesn't have any experience of welding or brazing to just go for it because it's the kinda thing that you can learn with a few minuites of trial and error.

[Eclecticos]

yes crazy is right about the brazing. here isa brazed joint.

notice on the brazed joint its a goldish colour and not the same colour as the parent metal like in the welded picture.

Thats why you do a Silver Brazing, with silver Brazing Rods. So you don't end up with that God awful Yellow color.

[crazybillybob]

Thats why you do a Silver Brazing, with silver Brazing Rods. So you don't end up with that God awful Yellow color.

That yellow color is Brass from the rods... There are many cases that you'd use brass over silver..plus most guys that are brazing only keep brass around because it's the most flexible to use (Ie it works well on more metals). It's used allot on cast Iron, because it's expansion rate and ductility is close to that of cast iron.
The silver brazing is used mostly on white metals (zinc, Aluminum, pot metal, etc).

Cal,
The fact is you can weld (not braze) Aluminum with a TIG, MIG, DC buzz box (electric Arc welder) (takes a special rod), or with oxy-Acetylene (takes an aluminum specific flux, and can cause more aluminum oxide to form in the weld..untill your good at it). Now I will say that I have not welded aluminum all these ways, but I've talked with older welders that have and read the manuals that explain how it's done.... My Mig will be switched over to Aluminum here soon (need a weekend that I'm not working or moving to switch it over and play!)
The thing with aluminum is that it takes a bit more heat, and is less forgiving then welding steel... best word of advice, Preheat! Get that Aluminum up to about 250-300degF before you spark up a bead (thinner sheet doesn't need the heat, but anything over about 1/8 inch...does).
If your really interested in welding Aluminum with something other then a TIG, do a Google search on it, there are many good sites that will show you the basics.

CrazyBillyBob

[Spawn-Inc]

The fact is you can weld (not braze) Aluminum with a TIG, MIG, DC buzz box (electric Arc welder) (takes a special rod), or with oxy-Acetylene (takes an aluminum specific flux, and can cause more aluminum oxide to form in the weld..untill your good at it). Now I will say that I have not welded aluminum all these ways, but I've talked with older welders that have and read the manuals that explain how it's done.... My Mig will be switched over to Aluminum here soon (need a weekend that I'm not working or moving to switch it over and play!)
The thing with aluminum is that it takes a bit more heat, and is less forgiving then welding steel... best word of advice, Preheat! Get that Aluminum up to about 250-300degF before you spark up a bead (thinner sheet doesn't need the heat, but anything over about 1/8 inch...does).
If your really interested in welding Aluminum with something other then a TIG, do a Google search on it, there are many good sites that will show you the basics.

CrazyBillyBob

so you doo need flux for aluminum, when ever i messed around at work trying to weld it it just melts and get a skin (layer oxide) all over it. i was doing it with oxy-Acetylene. but yes i have heard tig is the best for aluminum. i would love to have a tig welder but i'm spending my money of my gaming rig right now. also i don't do nearly enough, though i guess if i had my own i would, welding to make it worth the supplies, and tig machine.

[hd431]

Durafix
Alumiweld
Technoweld

Is it a braze, weld, both or neither?

Perhaps its a high temperature glue for Aluminum joining applied with a propane torch?

The rods composition is a secret but apparently they do contain some Magnesium and Manganese which strip the oxygen atoms away from the problematic
Aluminum surface oxide layer that the molten puddle is covering.

But this oxygen theft only happens with a little help when you must scratch the aluminum surface covered by the molten Durafix puddle with the stainless steel wire tool supplied. Scratch. Scratch.

. This triggers a chemical reaction and produces a lot of heat. They say enough to melt the now pure aluminum surface (maybe an atom of 2 thickness?) and allow perfect welding of whatever this Durafix stuff is onto the aluminum under it.

Actually very very clever.

Since a chemical reaction is taking place this stuff might qualify as unique type of aluminum glue.

The Manganese oxide and Magnesium oxides float to the top of the puddle.




Key things need to be done differently. If you use these rods like ordinary braze or weld rods you'll fail
and get inferior or no bonds at all. They show why. Some interesting science is involved with this stuff.

The bond is stronger than the aluminum. No flux is needed. No fumes are produced.
No need for welding goggles as there is no bright glare. No clean up needed unless you want to
grind and polish the join.

three good videos explaining how its used.

http://www.youtube.com/watch?v=nxtmt6QCVd8

http://www.youtube.com/watch?v=Bu2bq...eature=related

http://www.youtube.com/watch?v=-Sae5...eature=related



other info and tips here.

http://durafix.com/

http://www.techno-weld.co.uk/product.html

http://www.alumiweld.com/