Which argon mix to go for?

[Munkul]

Thankyou for the input .. I will defo switch to a light mix now and fingers crossed it will help my spray application )

Probably will, if it's a true 26 volts, but it sounds like you're actually in a lazy globular transfer if you have to run a long stickout to stop it popping. It should never pop. Crackle, yes. But no pop.

Either way, don't worry about it, just set your wirespeed for the thickness and set volts for the bead size/avoiding spatter.

 

[Country Joe]

It’s one of the delights of “more mature years”, everyone expects you to be a grumpy old git so why disappoint them

Well, I'm definitely qualified - and everyone should aim to please!
CJ

 

[Ed.]

I'd already covered that, earlier:-

For further reference it's:-

2% Oxygen, 5% Argon & 93% Carbon di-oxide.

CJ

I think that the Argon and the CO2 are around the wrong way!

 

[backpurge]

I think that the Argon and the CO2 are around the wrong way!

No, that’s perfectly correct (Argoshield Light mixture)

 

[Country Joe]

I think that the Argon and the CO2 are around the wrong way!

No, that’s perfectly correct (Argoshield Light mixture)

Phew! Just in time - I was just about to apologise!
But I might have checked, first!
(Probably not, though!)

All the Best,
CJ

 

[Munkul]

I think that the Argon and the CO2 are around the wrong way!

Correct.

No, that’s perfectly correct (Argoshield Light mixture)

Wrong.

Argoshield light is mostly Ar, with a small amount of CO2 and an even smaller amount of O2.
A "heavier" gas simply has more CO2 content.

 

[Country Joe]

Correct.


Wrong.

Argoshield light is mostly Ar, with a small amount of CO2 and an even smaller amount of O2.
A "heavier" gas simply has more CO2 content.

Christ! How did I get into this!

You're right, and I've actually checked, this time!
I (obviously) wasn't really thinking about it too hard - I do realise it's mostly Argon, but maybe only if I stop to think!

The embarassing bit is that I checked before I first used those figures - as like I'd said - I don't even know what's in it.
I mean I did once, but I've probably forgotten since. Just like when I read it from my screen & still put it down wrong on here!
After a duration of only seconds!

See, it's so bad, I'm forgetting how to end a post!
Anyway, once you get to a certain age, you hardly remember what you......

All the Best,
CJ

Oh, yeah....
....looked like yesterday, come the morning!

 

[Munkul]

I know there are a few subtleties, but these are very small changes of effect, and quite difficult to understand. I have to admit I don't get them, and i also don't need to know... more about metallurgy and weld wetting characteristics.

Sorry I can't correct my post now, but looking back through the thread I realise I had actually misunderstood the HUGE difference between CC and CV gas characteristics.

I was wrong about the ionization potential I always try to understand something in it's simplest terms. In Terms of ionization potential, the rising order is CO2, Argon, then Helium. This doesn't really explain the welding characteristics very well!

https://www.thefabricator.com/thefa...bles/choosing-shielding-gases-for-arc-welding
https://www.esabna.com/euweb/mig_handbook/592mig4_6.htm
https://www.sciencedirect.com/science/article/pii/S2211379718308118

So here goes again.

Arc length is the one I still best understand... And the biggest change of effect, in both CV MIG and CC TIG.

There's two different scenarios: CV MIG gas change (Argon-CO2), and CC TIG gas change (Argon-Helium).

CV MIG - put a "heavier" gas in there like more CO2 - it closes arc length, changing weld characteristic for the same settings. It does NOT raise the current. The voltage will not change, because the arc length self-adjusts, lowering the total resistance back down. You can then set a higher voltage to set the arc length back to where it was, and then you have more total energy going into the weld pool.

How does it do this? Apparently through some fairly complex chemical interactions. I'm not actually sure, my research only leaves me more confused! But you don't get power from nowhere, and breaking the carbon-oxygen bonds is an endothermic reaction, not exothermic. Whatever the mechanism, the actual effect is that the short-circuit current lessens, so burns off less, and the arc shortens in total. No extra energy is going in, until you adjust the machine - it just changes the arc characteristics.

CC TIG - put a "hotter" gas in there like Helium or Hydrogen - arc length stays the same, since it's controlled manually - voltage rises to keep same current setting - more arc energy in total. Much simpler than CV MIG because there are less variables. Helium = higher arc voltage = higher power.
How does it do this? As well as additional cooling effect from the the thermal conductivity, the arc column is wider, with lower current density, which means the resistance of the arc is higher. Higher R, with constant I, = higher V.

One thing is certain. You don't get energy from the gas. It's physics. V=I.R, and Power = V.I - these two formulas govern the welding process... all you have to do is make sure that energy goes into the weld puddle, and not everywhere else

 

[backpurge]

No, that’s perfectly correct (Argoshield Light mixture)

My mistake totally, didn’t read the post properly, just fell out of bed when I read it
The correct mixture of Argoshield Light is - O2 2%, CO2 5%, balance Argon, apologies for any confusion caused

 

[Ed.]

That's OK, for a minute there I thought I was loosing it too despite the fact that is what I use as my MIG gas mix , but I didn't think that I had developed dyslexia or senility ....yet!

I know what the correct gas ratios are but after seeing what you wrote in writing I had to double check that I wasn't seeing things wrong.

 

[Country Joe]

That's OK, for a minute there I thought I was loosing it too despite the fact that is what I use as my MIG gas mix , but I didn't think that I had developed dyslexia or senility ....yet!

I know what the correct gas ratios are but after seeing what you wrote in writing I had to double check that I wasn't seeing things wrong.

My bad, really - I should think more carefully, before I first "informatively" type stuff!

All the Best,
CJ