Joining aluminum by torch? (welding, brazing)

[Joel_BC]

Can anyone tell me one or more ways that aluminum components can be welded or brazed? I need to learn the basic info, and can practice to get the proficiency. That is, if the equipment I have is usable for the task.

The tools I own are a propane/air torch, and an oxy-acetylene rig (with various size tips from Victor 00 to 5, plus rosebud). I don't have a MIG welder.

Brazing: If feasible, would this generally be the best approach (rather than welding)? What sort of rods (brass, bronze, or other) should be used? And would a different flux from that used when brazing steel or brass be required? (My current brand of brazing flux says nothing on the container about aluminum, but designates the powder as being good for "ferrous and non ferrous metals".)

Welding: Can torch welding of aluminum be accomplished? Are somesort of fluxed rods needed for the purpose?

 

[the_whingnut]

ok you can braze aluminum but i personally have only seen it done with aircraft aluminum. you can also stick weld aluminum but the rod for it is called "popcorn rod" as a Nickname / derogatory term. its nasty low penetration and great for went you are up Sh*t creek. their is a aluminum mircle braze rod on the market you can find online it lets you braze with propane heat but it always broke on me for anything with a load. patching holes in tanks and fender the little rod was good. the two best ways to weld aluminum is to GMAW (Gas metal Arc Welding(mig))or GTAW (Gas Tungsten Arc Welding(tig)). If you intend to get a GMAW machine you have to buy a unit that does 220v with a spooler gun. not cheap but very good stuff. doing Aluminum just costs money to get set up and its tricky to weld has to be very clean to weld and its like welding on the edge of a meltdown. but once you get it down its fun! www.weldingtipsandtricks.com covers some good stuff.

also found this for trim and body work on aluminum but nothing load bearing. I am a welder not a brazer so i'm biased, but if i find some aluminum braze rod i might try this....
http://www.youtube.com/watch?v=RRWmpSE-hXk

i have used it its crap for load bearing and load carrying cast aluminum
http://www.ebay.com/itm/ALUMALOY-Al...CI%2BUA%2BFICS&otn=21&pmod=110673354223&ps=54

great thanks for asking a welding / brazing question now i'm going to have to learn to do it too. vid and pics to follow.
TSC and homedepot seem to carry aluminum braze rod.

i've got some scrap aluminum to try on nice ashy/ pitted nasty stuff i can barely GTAW.

 

[the_whingnut]

oh something to know what that guy in the video is calling a "soft flame " is a carburizing flame where you have the acetylene set to were the flame isn't putting off smoke, then adjusting the oxygen in to were the flame no longer has any hint of orange flame but no more.


i'll post more on it later.

 

[the_whingnut]

alumaloy stuff is good for patching aluminum boats and small tanks. but everything has to be clean inside and out for holes / cracks and no flux.

 

[Joel_BC]

Thanks for bringing my attention to all that, whingnut. I doubt I'll invest, very soon anyway, in MIG. A neighbor has a MIG machine... he'll let me use it to learn on, now and again. But he only has steel wire for it, as he doesn't work with other metals.

also found this for trim and body work on aluminum but nothing load bearing. I am a welder not a brazer so i'm biased, but if i find some aluminum braze rod i might try this....
http://www.youtube.com/watch?v=RRWmpSE-hXk

That is one cool vid! The guy obviously is an expert.

I realize he isn't melting the parent metal, but using the aluminum flux-core rod to braze with... well, the result almost seems like a welded bond. From what you can see... I mean, once it's sanded, filed, re-sanded and buffed, it appears like solid metal. You think it would be less strong (for structural stuff - say, with 5mm plate-aluminum parts) than actual aluminum welding?

I suppose it might be less strong, simply because the parent metal isn't melted to mix in with the aluminum from the rod, eh?

Also, he's using a small torch - not the usual medium ar large-size Victor-type torch handle. I do have a smaller torch handle with some quite small tips. I haven't used it for very much, but a few times for delicate brazing. I can connect up that smaller torch onto my hoses if I want to try aluminum brazing. The guy in the vid just brushes the meta with the flame, kind of across the metal. Different from how you hold the torch tip to weld steel with a torch, and even different from how you hold it to braze steel.

 

[the_whingnut]

First off

Brazing - the heating of base metals and adding a filler metal at the point were they bond

Welding - the heating of base metals and adding a filler metal at the point at which they fuse.


anything brazed can be removed by reheating and wire brushing or applying force.

anything welded, the joint / weld zone must be cut / ground / filed away including a little apove the joint and below.

big differences in application / process

as for oxy/acetylene welding you have to use welding tips not brazing the difference is the amount of heat being use. you can use a brazing tip for welding but more for small stuff.

all the tips for brazing have the same temp range, same for the cutting tips and rose buds

the different is the amount of that heat being let out.


you can use the large torch you just have to be confidant, sharp eyed and fast with the hands.

you need to know the type of flame you have carburizing, oxidizing, neutral or soft , hard, medium respectively.

also most of my knowledge is Naval Ship repair based / farmboy repairs (i can pull some stuff out when i need to) so i'm not all knowing i just know what i know. my conventional welding knowledge started in high school for local industry so my view is kind specific.

 

[Joel_BC]

Great to have a guy of your experience and abilities posting here!

First off

Brazing - the heating of base metals and adding a filler metal at the point were they bond

Welding - the heating of base metals and adding a filler metal at the point at which they fuse.

Yeah, I know. I started off brazing steel (flux, brass/bronze rods,etc). Then I learned mild-steel welding with the O/A torch.

anything welded, the joint / weld zone must be cut / ground / filed away including a little apove the joint and below.

big differences in application / process

Yeah. I guess because his example was one of refurbishing trim (a low-stress, low stregth requirement), welding was not so necessary.

as for oxy/acetylene welding you have to use welding tips not brazing the difference is the amount of heat being use. you can use a brazing tip for welding but more for small stuff.

When I braze steel, I'm usually using the Victor #0 tip... sometimes the #1. With welding steel, I generally use any where from #2 to #4.

all the tips for brazing have the same temp range, same for the cutting tips and rose buds

the different is the amount of that heat being let out.

Yeah. Neutral flame about 6300* F - right at the point of the inner cone.

you can use the large torch you just have to be confidant, sharp eyed and fast with the hands.

you need to know the type of flame you have carburizing, oxidizing, neutral or soft , hard, medium respectively.

also most of my knowledge is Naval Ship repair based / farmboy repairs (i can pull some stuff out when i need to) so i'm not all knowing i just know what i know. my conventional welding knowledge started in high school for local industry so my view is kind specific.

For brazing steel, I've tended to use a soft neutral or carburizing flame.