Tig welding aluminium AC or DC

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Is it possible to weld alluminium using a DC tig welding machine or do i need to buy a DC rectifier? as i have heard you need AC to weld alluminium is this true?
Reply:There has been some stir lately of a few guys on the Hobart forum using DC for alum. I haven't tried it myself but with some practice, it works from what I've read and seen.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:You can use DC.  You will need a tri mix to help run hotter.  Also pulse works fine with it.  I will find out at work why they weld our bores with DC and the rest of the magnet with AC.  I will then repost my finds for you, give or take around this same time tomorrow.
Reply:A well proven method of welding heavy aluminum, 3/8" and thicker, is to TIG with DCEN and 100% Helium.  I have done a good deal of this and it woriks very well, although as with any form of aluminum welding the material must be very clean and the oxide freshly removed with a SS wire brush.  In AC welding, the DCEP portion of the AC wave acts to "clean" surface oxides, but it also acts to heat the tungsten electrode and reduces the max current you can run.I have not tried He/Ar mixes, but in theory a mix, or even 100% Argon should also work, the effect being that less heat is transfered through the arc as the percentage of Argon increases.
Reply:Originally Posted by yom_johnIs it possible to weld alluminium using a DC tig welding machine or do i need to buy a DC rectifier? as i have heard you need AC to weld alluminium is this true?
Reply:Im in the UK and there are a lot of DC only machines sold over here and in europe. Used a lot for site work where a gen set would be too heavy and or big to place close to the work area
Reply:--------------------------------------------------------------------------------A well proven method of welding heavy aluminum, 3/8" and thicker, is to TIG with DCEN and 100% Helium. I have done a good deal of this and it woriks very well, although as with any form of aluminum welding the material must be very clean and the oxide freshly removed with a SS wire brush. In AC welding, the DCEP portion of the AC wave acts to "clean" surface oxides, but it also acts to heat the tungsten electrode and reduces the max current you can run.
Reply:Originally Posted by Shox DrIm in the UK and there are a lot of DC only machines sold over here and in europe. Used a lot for site work where a gen set would be too heavy and or big to place close to the work area
Reply:Some years ago i saw a demo from miller using dc helium  and continuous hf to weld ali,but the way to go is ac.
Reply:Originally Posted by WashmanYes, but are you talking about straight "Stick" type welding machine or "TIG"?You mean the machine plugs in the wall so to speak and is only DC?Washman
Reply:Originally Posted by WashmanYes, but are you talking about straight "Stick" type welding machine or "TIG"?You mean the machine plugs in the wall so to speak and is only DC?Washman
Reply:dc tig aluminum get some 90%he10%arg the argon helps hold the arcChuckASME Pressure Vessel welder
Reply:Originally Posted by chopper5dc tig aluminum get some 90%he10%arg the argon helps hold the arc
Reply:And one other overlooked thing...The tungestion must be sharp to do DC aluminum.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.