Newbie aluminum welding question coming your way.

admin

Hi all  If you're using a multi process machine (Mig/Tig/Stick) that is a DC only machine why can you weld aluminum using a spool gun on the mig process but not on the tig process? This has me a bit confused.Thanks
Reply:If you can hook up the spool gun, then yes. TIG aluminum is strictly AC, while aluminum wire is DC+, just like regular steel MIG. There's no point in setting the machine to run TIG if you want to run wire.Last edited by Hillbilly Welder; 06-07-2016 at 05:15 PM.
Reply:aluminum has a very weld unfriendly oxide layer that you have to deal with.   the tig process uses AC  to overcome the oxide layer.  spoolgun  use  spray transfer (not short circuit) to deal with that oxide problem.   they are completely two different processes its not necessarily an AC vs DC  scenario.
Reply:Originally Posted by Weld_aluminum has a very weld unfriendly oxide layer that you have to deal with.   the tig process uses AC  to overcome the oxide layer.  spoolgun  use  spray transfer (not short circuit) to deal with that oxide problem.   they are completely two different processes its not necessarily an AC vs DC  scenario.
Reply:Originally Posted by Hillbilly WelderIf you can hook up the spool gun, then yes. TIG aluminum is strictly AC, while aluminum wire is DC+, just like regular steel MIG. There's no point in setting the machine to run TIG if you want to run wire.
Reply:With the flow of "negative" electrons goes heat. In the TIG process we need electrons to flow from the tungsten to heat the workpiece. It forms a liquid puddle. We then dip filler in the puddle. Heat transfers to filler melting it. With the heat drawn away, the puddle freezes. Hence, the stack of dimes. Steel stays adequately clean. We use DC EN. Clean aluminum instantly bonds with oxygen forming aluminum oxide. Oxide melts at a temperature twice that of clean aluminum. Using AC blasts oxide off the surface of aluminum along with the negative ions.   TIGging aluminum calls for both EN to heat the workpiece, and EP to clean it.   In argon atmosphere, it won't oxidize.MIGing aluminum, (spool gun) uses rapid expansion to jet metallic droplets onto the surface of the joint. Electrons bring heat to the filler wire along with oxides from the piece. Jet action sprays it at the work.WillieAn optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:The short answer is you can't AC for aluminum Tig with a multiprocess welder. The short version of the long answer is your machine will not have enough power to DC tig aluminum as is done in some industries Sent from my SCH-I605 using TapatalkRyanMiller Multimatic 200 tig/spool gun/wireless remoteMillermatic 350P, Bernard/XR Python gunsMiller Dynasty 350, Coolmate 3.5 & wireless remoteCK WF1 TIG wire feederMiller Spectrum 375 XtremeOptrel e684Miller Digital EliteMiller Weld-Mask
Reply:Originally Posted by Weld_aluminum has a very weld unfriendly oxide layer that you have to deal with.   the tig process uses AC  to overcome the oxide layer.  spoolgun  use  spray transfer (not short circuit) to deal with that oxide problem.   they are completely two different processes its not necessarily an AC vs DC  scenario.
Reply:Yup, DCEP is what breaks up the oxide layer as the electric arc goes from the base metal up to the electrode.OP, remember that DC is "direct current", but there are two ways DC can flow, Electrode Negative (towards the base metal), or Electrode Positive (towards the electrode on the welder). 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:Originally Posted by MinnesotaDaveI would respectfully disagree with the spray transfer statement.  It's the DC+ that cleans the oxide layer from the aluminum.
Reply:You can TIG Aluminum with DCEN and helium with that machine, but there's no cleaning action from the arc. You can get cleaning action out of the spool gun, because it's DCEP. Use a push angle to keep the clean area ahead of the puddle.SqWave 200Millermatic 190Airco 200 ACHypertherm PM45Boice-Crane Band SawVictor O/A
Reply:As an experiment I tried DCEN on aluminum. It was necessary to puddle deeply, and shove filler under the oxide layer. If desperate I think it could work.WillieAn optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.