Helium Shielding

[Wotsit]

Hi,

I was wondering if anybody has any experience of using helium or helium argon mix for shielding when welding aluminium. I have use of an ac welder but only at work, and i am considering a new project that will be to big to transport.

Thanks in advance,

 

[Wotsit]

Sorry should have made it clear that i intend to use a dc welder (Inverter fusion 200 PHF)

 

[Paul.]

I sometimes use BOC Alushield universal with my optipuls synergic mig set, with amazing results, its pretty expensive though, depends on the project, great for positional work

 

[Wotsit]

Have you used it with your tig on DC for Alu TigPaul?

 

[dstealth]

You cannot weld aluminium using DC current, only AC!!

 

[Wotsit]

Sorry dstealth you can indeed weld aluminum with DC, helium raises the temperature of the arc and aids deper weld penetration. I was hoping somebody might have experience of using this technique, before I go out and buy a expensive bottle of helium.

To quote http://www.arcraftplasma.com/tigwelding.htm

"When ac is used with argon shielding, an arc cleaning action is produced at the joint surfaces on aluminum and magnesium. This cleaning action removes oxides and is particularly beneficial in reducing weld porosity when welding aluminum. When using dc, helium may be used as the shielding gas to produce deeper penetration. However, stringent precleaning of aluminum and magnesium parts is required with helium shielding. Argon and helium mixtures for gas shielding can provide some of the benefits of both gases."

 

[Drains]

dstealth and wotsit, you are both not quite right!

You CAN use dc Tig to weld ally, but you need to use electrode positive (normally you'd use elec neg) The problem with this is that you need a whacking great electrode, as a small one will burn out smartish.

re wotsit's quote, you still need the cleaning action, however deep the penetration and however fancy the gas, cos you won't penetrate the oxides formed, they must be cleaned away. I havn't tried this, so I can't say with absolute certainty that stringent precleaning wouldn't work, but seeing as the oxide is produced immediately on contact with air, I reckon successful welding with elec neg and helium is pretty unlikely.

 

[Paul.]

Have you used it with your tig on DC for Alu TigPaul?

Yes I have, but compared with pulsed AC really not worth doing, the residual oxide is removed by the AC cycle, this is known as a scavenging effect, with DC you have to manually clean and weld almost straight away, I think its probably intended for automated welding on heavier sections, not much experience with this though.

 

[Wotsit]

Thankyou for the advice, i'll forget about this idea and move on to something else! Looking at a few bit of copper for the next project......