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Thread: Does aluminum require AC or DC for welding?

  1. #1
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    Default Does aluminum require AC or DC for welding?

    I know that on TIG, AC is used for aluminum because the polarity reversal is suppose to help clean the surface. I'm not very clear on the mechanism but that's what I've read.

    I've noticed that Lincoln Electric MIG welders uses DC for welding aluminum.

    Can someone explain why DC is used for MIG while AC is used for TIG, in the case of welding aluminum?

  2. #2
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    Mig is a completely different creature. Nothing is the same, current, gasses, etc.

    I have never been a fan of aluminum Mig welding. The lower end machines will do it, but not well. I have only seen in recent years a couple high end Miller machines that do a good job with aluminum Mig, but they are $8,000 welders. They better be able to weld Aluminum, steel, the crack of dawn, and make me coffee and breakfast while they are doing it.

    We do a lot of welding here, but Tig is king followed by Stick. Mig is for sheet metal and some other light non critical work. We only weld Aluminum with Tig.

  3. #3
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    Aluminum is generally TIG'd with AC but can be TIG'd with DC using helium and a fair sized machine.

  4. #4
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    Yup, you can TIG (GTAW) weld aluminum with DCEN... Depends on what you are welding and with what you are welding, the consumables.. JR
    Last edited by JRouche; 05-26-2010 at 11:37 PM.

  5. #5
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    You can easily weld aluminum with MIG if you have enough power (in general, at least, a 185 Amp machine) and a spool gun. You can do it without a spool gun too, but it'll be a headache.
    Last edited by MichaelP; 05-27-2010 at 12:17 AM.

  6. #6
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    For aluminum, as noted, with a TIG the AC "back and forth" cycle helps blow oxides off the weld pool. With a MIG, the same basic idea is produced by the "make and break" cycle as the MIG wire contacts the work, melts, breaks contact, makes contact again, melts, breaks contact, etc.

    Aluminum has been MIG welded with great success for many years, and it doesn't take a particularly impressive machine to do so. It takes a somewhat specific kind of machine (constant current, I believe) but like all welding processes these days, advancements in technology have brought the "exotic" machinery- like TIG and spoolgun MIG- closer to home-shop affordable.

    On the other hand, I don't recommend the little 110V "box store special" MIGs for aluminum- then again, I don't necessarily recommend them for welding steel, either, after having used them extensively for many years before finally buying a "real" MIG...

    Doc.
    Doc's Machine. (Probably not what you expect.)

  7. #7
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    Quote Originally Posted by Doc Nickel
    Aluminum has been MIG welded with great success for many years, and it doesn't take a particularly impressive machine to do so. It takes a somewhat specific kind of machine (constant current, I believe)
    Just a regular MIG machine (constant voltage).

  8. #8
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    Aluminum mig is a hot process. Usually you are in a spray arc and that dumps a lot of heat into the gun. My nozzles often turn black welding aluminum. Aluminum is one of the only processes that actually benefit from pulse mig. With a good pulse mode you can get a bead that looks like a tig weld.

  9. #9
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    Quote Originally Posted by MichaelP
    Just a regular MIG machine (constant voltage).
    -I knew it was one of the two.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  10. #10
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