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Thread: Brazing aluminium? Anyone tried this?

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    Default Brazing aluminium? Anyone tried this?

    http://www.aluminiumrepair.co.uk/htm...ical_info.html

    Looks good. Is there a catch, or is this as good as it looks?

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    What do you mean? It's basically just gas welding... nothing new. Just a better filler rod.

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    You can get a older generation AL rod at home depot, try it before paying $$

    the trick is to get all the oxide off the aluminum and very quickly use the special rod before it oxidizes again. Its NOT like soldering or brazing, in that it doesnt flow very well, but it will stick to 6061 and other Al alloys, but nothing else, ie its AL to AL only. Nor does it remelt I have a friend who builds
    19" racks out of it, good for but joints and well prepared corners with 45' mitres on them pre weld, other then that, get out the drill and tap. still fun to play with and works with a propane torch.

    Steve Roberts

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    Ever do any aluminum MIG welding? I have a MIG setup but only for steel. I can get a special spooler for aluminum wire but haven't because I am unsure of how it will work.

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    Quote Originally Posted by carmangary View Post
    Ever do any aluminum MIG welding? I have a MIG setup but only for steel. I can get a special spooler for aluminum wire but haven't because I am unsure of how it will work.
    I've only done TIG and GTAW at work,and gas brazing/cutting of steel at home But thats a whole different setup.I Dont know personally, but my cousin the racecar nut uses mig for some amazing sheet metal stuff.

    Steve

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    I've got a neighbor that practices stick-welding aluminum in his garrage. He's got a MIG/TIG welder too, but he likes to weld aluminum with his regular arc welder every once in a while just to keep his proficiency up. (He's a mechanic for a large paper mill here in town.) He says it's tricky, but I've actually watched him arc-weld 1/8 inch thick box aluminum. Not sure what sort of rod he uses though. (I didn't know it was even possible to stick-weld aluminum!)

    I imagine brazing would be pretty easy, since the temps involved are way below the melting point of aluminum. MIG would be my second choice though.

    Adam

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    It can't be the same as welding, or people would just weld...

    What looks good about it is the description of being able to 'tin' an almuminium surface. That implies flowing freely and displacing the oxide layer, and staying ready to easily bond to another similarly prepared surface. That would be like soldering, but with more than the strength of brazing (bond stronger than the filler material, if applied thinly and evenly). It's an unusual extra, having the bond stronger than the substrates. Doing all this with just a torch flame and no flux is especially tempting.

    If it's true, then for accurate parts this could be better than drilling and tapping for many things. The question isn't whether it's better than welding or soldering, but whether the claims are true. If they are it's better than either, with the main (only?) weakness being that the maximum safe temperature for an assembly is reduced.
    Last edited by The_Doctor; 09-05-2007 at 10:07.

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    Quote Originally Posted by The_Doctor View Post
    It can't be the same as welding, or people would just weld...
    Technically, when you use a torch it's called brazing, not welding, so yeah, it's different. In this case they even admit that the temperature is lower (750 or so), where as welding will get you right up to the melting point.

    Nevertheless, if the marketing info on that site can be believed, it sounds as if the joint is actually stronger than the aluminum itself. I'd be interested to see some independent verification of that though.

    Brazing is a lot easier than welding, and takes less skill to perform. (When I was in the Navy, the welding school for MM's was 9 weeks long. The brazing school, which I actually attended, was only 1 week.) So if it's as good as a weld and easier to do, I can see where they'd make a good bit of cash selling it. But like I said - I'd like to see proof that it's as strong as a weld...

    Adam

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    Personally I wouldn't waste time or $ on that. Filler rods are cheap for the TIG machine. It is still best to preheat the item to be welded after a very aggressive cleaning and acid etch. Stainless 604 and 4130 chr-moly seems to be most forgiving. Aluminum is another animal to tame. The MIG does good with a spool gun in production areas where fixtures are used....Miller 250 series has enough amperage to do well here. Miller has a new square wave TIG machine that welds alu alloys very well....even a smaller unit for 120 Vac...


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    I think that if you want accuracy with small stuff you would be better off milling nice surfaces and fastening with screws. Metal tends to distort when heated. Especially little stuff.

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