How can i weld aluminum using my dc inverter tig wekding machine

[Michael millena]

Can i wekd aluminum using this tig welding machine

 

[Mr Roo]

Simple - use helium, not argon!

but on the offchance that helium is far too cost-prohibitive, you’re gonna need an AC welder.

 

[Tangledfeet]

Simple - use helium, not argon!

I had no idea - I take it that the helium negates the need for the cleaning action provided by the AC cycle as it prevents the aluminium oxidation?

 

[Mr Roo]

I had no idea - I take it that the helium negates the need for the cleaning action provided by the AC cycle as it prevents the aluminium oxidation?

not 100% sure on the science of it all, but I know that Helium burns hotter so might just break through the oxide layer easier?

 

[zzr1200]

Can i wekd aluminum using this tig welding machine View attachment 275513

Ermmmm..

Not really unless it very very thin aluminium, it's all to do with the heat the tungsten has to absorb....I'm sure Richard or one of the others will be along soon explain why in more detail...

Plus the cleaning action of the ac arc

 

[eSCHEn]

You have two parts of the AC waveform which correspond to the high and low parts of the wave. At one point the wave produces 100% cleaning action, removing the oxide layer (which has a very high melting point). At the exact opposite point of the wave the action changes to 100% penetration, melting what is in front of the tungsten. The pure Al (with no oxide) melts a lot more easily that with the oxide layer.

By balancing the cleaning vs penetration you get a nice weld on AC.

With DC you are restricted to one or the other. You can either run DCEN and get penetration but no cleaning or DCEP and get cleaning but no penetration (or the other way around, I forget and SWK will correct me). The other problem with DCEP is you're eating the tungsten and so you need a much larger size to cope with the power. I have some 4mm ones here to try at some point.

If you clean the Al and then weld it on DCEN with pure Ar then you'll get some penetration but not a massive amount, maybe 1.5 - 2mm at a push on pure Ar and 200A? The issue mainly is you'll spend ages getting a pool and then PLOOP it's super liquid and you need a very fast action to catch it.

He, as I understand, is more excitable in terms of the electrons and so 'punches' harder and gives more penetration. Again, SWK will correct / add I'm sure

 

[backpurge]

Reverse the polarity, stick in a much bigger tungsten and use a gas with at least 75% helium in it

 

[heldtogetherwithblutack]

Heavy industry and marine use DC on aluminium, years ago when the Seacat was first operating had interesting chat with onboard engineer regarding construction. Google throws up this:-

11 Tips for TIG Welding Aluminum with DC - Welding Mastermind

When TIG welding aluminum, alternating current (or "AC") is almost always used. Alternating current has a scrubbing effect on the surface, breaking up oxides

weldingmastermind.com

 

[Tangledfeet]

Well... what about aluminium MMA rods? I didn't know they were a thing until recently!

 

[Hood]

Well... what about aluminium MMA rods? I didn't know they were a thing until recently!

And now you have heard about them it is better to forget about them

 

[Mr Roo]

And now you have heard about them it is better to forget about them

aye - aluminium ones are specifically called MMA rods because it takes a fair scrap to get them to do anything right!

 

[Hood]

aye - aluminium ones are specifically called MMA rods because it takes a fair scrap to get them to do anything right!

Step brothers bought a box to do small repairs to their boats to save me having to haul myself and my gear out (I always moan about these jobs ) They couldn't get them to work so brought them down to see if I could. I managed by bumping up the current and pushing them in as fast as I could. They worked, it wasn't pretty but not too ugly either but wasn't that strong, it would have done for filling the wear grooves up as they had bought them for but they just couldn't get the hang of them so now I have sold them my old EWM Phoenix 330, still have to give them a few lessons, should be fun

 

[Tangledfeet]

And now you have heard about them it is better to forget about them

aye - aluminium ones are specifically called MMA rods because it takes a fair scrap to get them to do anything right!

Serious question; would they be any better or any worse than DC TIG with Helium gas then?!

 

[Hood]

Serious question; would they be any better or any worse than DC TIG with Helium gas then?!

Never tried DC tig, heard it is like stirring soup through porridge. I wouldn't fancy having to use either except in an emergency so that is as good as my answer gets

 

[Mr Roo]

Serious question; would they be any better or any worse than DC TIG with Helium gas then?!

i’m sure i saw a video of Jody from wt&t showing it which is how i’m aware - from what i gather it gives insanely good penetration; but the weld isn’t as nice looking. Iirc his explanation is that it’s used for heavy parts that need solid penetration profile and then usually an AC&Argon run over that for the rest of the weld.

EDIT: found the vid...

 

[Tangledfeet]

I found a different one and the results were pretty darn good, certainly compared to most amateur (mine anyway) aluminium welding on AC!

 

[backpurge]

Used to sell quite a few small DC TiG inverters to the RAF for ground crew to use carrying out repairs on aircraft that were parked up on the runway ready to scramble

 

[TechnicAl]

Well... what about aluminium MMA rods? I didn't know they were a thing until recently!

Aluminium Rods are only used when nothing else is available

as for DC TIG....follow Backpurge instructions and make sure you clean the job thoroughly first....if possible use burrs

 

[E T]

Well... what about aluminium MMA rods? I didn't know they were a thing until recently!

And now you have heard about them it is better to forget about them

Modern day aluminium MMA rods aren't as bad as they used to be. I have a tin of AlSi12 rods that weld very nice.
Made some alu boxes out of 4mm sheet that turned out ok.

 

[TechnicAl]

Even the manufacturers dont like Aluminium rods.........the wet flux / coating is abrasive and corrosive....it ruins the mixers very quickly so the cleaning and maintenance time is out of proportion with the returns