TIG Weld Gas Question

[imagineer]

What is the benefit of 50%Helium/50%Argon shielding gas vs 100% Argon?

I've just finished up a large project that involved about 100 hours of TIG welding aluminum. All the material was relatively thin walled, .080" - .125", I used 100% Argon for all of it and it seemed to go well.

I recently tried TIG welding an aluminum project with heavier material, .250" walls, and my Miller Diversion 165 TIG machine didn't seem to have the amps needed.

Will TIG welding aluminum with 50/50 mix create more heat?

 

[racecougar]

 

[cvairwerks]

You're a little shy on power from the info I've seen.... Most info states 1 amp per .001" thickness on Al.

 

[imagineer]

You're a little shy on power from the info I've seen.... Most info states 1 amp per .001" thickness on Al.

Ya, that's obvious from the machine control dial. I'm just looking to get a little extra out of it.

 

[cvairwerks]

Ya, that's obvious from the machine control dial. I'm just looking to get a little extra out of it.

LOL....not going to be able to make up a deficit of 100 or more amps with that machine. Changing gas isn't going to be much help. Move over to an oxyhydrogen gas torch and you can do 1/4".

 

[speed bump]

Helium supposedly gives you a little extra umph. I haven't tried to get it but according to the internet helium blends are expensive and almost to get right now though.

 

[Siegel1719]

Helium conducts heat better than Argon. The difference is very slight I would guess in the 5-10% range. I have used 75/25 many times welding aluminum and it helps to get going faster and allow you to travel slightly faster but will not make up for a machine that is too small.

 

[imagineer]

Helium supposedly gives you a little extra umph. I haven't tried to get it but according to the internet helium blends are expensive and almost to get right now though.

I have access to free 80cf cylinders of welding gases.

 

[matt_i]

Where you are under capacitized you can always back-bevel and fill or multi-pass to create penetration at the root of the joint and build the fillet. Just speaking in generalities.

 

[zmotorsports]

I have not used the argon/helium mix nor any of the tri-mixes so I have no personal experience with any of them but I have read that they help to put a bit more punch into the heat input of the component. That being said, when we had our smaller TIG welder at work and I needed to weld a thicker weldment I would preheat the part to be welded and even with a slightly undersized/under-amped welder it would weld like butter.

 

[thammel]

Yep, helium is a much better conductor than argon. During my engineering days, we would fill sealed insulation cavities with either argon or xenon for low thermal conductivity. Helium, on the other hand created much greater heat flow due to its high thermal conductivity.

 

[welder4956]

What is the benefit of 50%Helium/50%Argon shielding gas vs 100% Argon?

Will TIG welding aluminum with 50/50 mix create more heat?

The benefit of adding helium to the mix when welding aluminum on AC is more heat is transferred to the base metal, higher arc voltage (2-3 volts for 75% helium/25% argon), and a wider bead profile. The trade-off is a slightly less stable arc and less cleaning action. The most common mix is 75% helium/25% argon. I have not welded with 50/50, but it should help a little on thicker material.

I have a 185 amp Lincoln machine and it is pretty much maxed out on 1/4" aluminum. It is slower to get the puddle going and travelling, but it can be done. If you think you will be welding much aluminum, get a bigger machine. It won't be good for the machine if it is running full out for very long and tripping the thermal overload frequently.

 

[imagineer]

It won't be good for the machine if it is running full out for very long and tripping the thermal overload frequently.

That's my biggest gripe about the Miller Diversion 165... the short duty cycle.
I'd love to get a larger TIG unit, with a water cooled torch, but am reluctant to cough up the dough for one.

 

[Steve from Socal]

Preheating the area to weld would help a lot with welding at low amperage. Heat the parts to 350 or so, the rest of the part wont be sucking the heat out of the weld.

Steve

 

[Jlarson]

I used to mix helium with our smaller machines, does help, along with preheat. Preheat really is a key when you're getting into thicker and or chunkier Al weldments, goes for TIG and spool gun work.

 

[sms1974]

You gain about 20% with a helium mix, you can try to grind out a bigger bevel, preheat it, and crank your machine to the max but I think your going to unhappy with the result… you need a bigger machine