100% CO2 is much cheaper and will last longer than 75/25. When you buy CO2, it is a liquid that off gasses as you use it, so it lasts longer. 75/25 or C25, 75% argon 25% CO2, is just gas and will produce a nicer looking weld with less spatter. CO2 will produce a hotter arc with deeper penetration.

So for thin material or work that has to be finished to a point where spatter will be a negative, I would use C25. But I am going to start using straight CO2, for cost purposes.

 

100% CO2 produces arc instability and a lot of spatter. The range of voltage and wire feed speed in which you get smooth, crisp arc performance is rather narrow. It tends to cause burn-through in thinner materials. It makes vertical, horizontal, and overhead welds rather difficult. It tends to cause welds with lots of slag and oxidation which needs to be ground off before painting.

In fact the only good thing that can be said of pure CO2 is it's dirt cheap and bottles last longer.

You should only use ER70S-6 wire with 100%CO2.

Note that you can manage burn-through in very thin materials by using thinner wires that draw less current, such as .030 or .025.

75%Ar + 25% CO2 produces a smoother arc with less spatter. It makes out-of position welds easier, especially if you use 70S-3 wire which has less puddle fluidity. Welds are a lot cleaner.

 

Once again here we go, I use 100% CO2 because I work on heavy equipment, and I can run hard wire(.045) and Dual Shield with it, it is cheap, and the 20 pound soda bottles fit nicely on my truck.

 

I'm no professional but I use co2 and I have very little spatter. I have used it on thin materiel and had no problems, you just have to know how to use it properly. I like it because it's cheap and it will make small welders run a little hotter. I have a hobart handler 140 I use as a portable welder and use the paintball bottles on it. It works great plugged into my generator.

 

I have never had a problem welding sheet metal with CO2 on my little MIG either.

 

Yes and No

It doesn't last longer but you get more for your $$ ( depending on your supplier)

1 # Co2 = 8.74 Cubic feet of gas

so in a little 20# Bottle you can get 174.80 CF of gas

My Supplier charges 30 bux

so cost/cheaper will depend on what your supplier charges for C25 mix equal to 174cf

 

I use 100% CO2 because I work on heavy equipment, and I can run hard wire(.045) and Dual Shield with it, it is cheap, and the 20 pound soda bottles fit nicely on my truck.

How long do those little cylinders last burning .045?

 

I get almost a whole roll out of a 20 pounder.

 

Tozzi, how big is the roll I am thinking of getting bigger tank.

 

33 pounder on the hard wire and whatever a 12" roll of Triple7 weighs. I cant be certian because I will run the same bottle on the mini MIG foe small BS jobs too

 

I get almost a whole roll out of a 20 pounder.

Gotta like that, since the little ones are light and easy to sling.

 

Do you need a different regulator for Co2(I have a millermatic 140)?

 

you can get an adapter but under heavy use it might freeze up. The adapter is less than $20 if I remember correctly.

 

Wow that's a lot of welding for a 20 pounder. Maybe I'll get two 20 pounders and keep one for back up. The 20# tanks are easy to store and handle. Thanks for the reply Tozzi.

 

Hi

Just a newbie question I have my welding jacket on so flaming won't hurt much.

I have a Lincoln 180C that i have just taken out of the box, 6mm/0.024" solid wire with 100% CO2. I have had a lot of blow through problems with 1-2mm (18 to 12 gauge) 0.040" to 0.081" mild steel. I read about the hotter CO2 weld and deeper penetration.
So if I adjust my voltage down (?wire speed) should I be on track ???

 

Maybe. There are a lot of other issues besides having the machine misadjusted that could cause burn thru issues. Having too slow of a travel speed being a big one usually. The lower thickness 100% Co2 will be tough. It's at the bottom end of whats doable with the "average" machine without a great deal of skill.


Voltage on a wire feed machine is usually done with the "power" settings, either a continuous adjustment or taps on some machines. Wire speed usually adjusts your amperage roughly, but it's adjusted in combination with your voltage. Mig is a constant voltage process, and the machine attempts to maintain a constant voltage allowing the amperage to vary as needed. Wire speed as well as how far away you hold the gun from the surface will change what the actual amperage is during the weld.

If you are having issues, start your own thread with picts of the problems ( especially the face side), machine you are using, type of joint and weld position, material thickness, machine settings, gas used etc, and we'll be happy to look at your welds and try to help you improve.

 

It's harder get good weld bead appearance with co2. It's also harder to set up a machine to get nice welds (in nearby factory they use pure co2 and you can't find any splatter around welds). So if you're on budget buy co2 gas.IMO if appearance of the weld bead is important to you, then buy mix. But for home use I think that, it's much beter to use co2, because it's alot cheaper and just good enought. You can even use modified co2 Fire extinguisher.

 

I've used straight CO2 for many years and have no problems of any kind with it. I do like that it is way cheaper and lasts much longer than mix gas. Like Tozzi, I like the added penetration and the ability to weld unclean steel in places that can't be cleaned. I wouldn't go back to mix gas for any thing.

 

Tell me more about the ability to weld unclean steel with CO2. A lot of the salvage iron I have here is pitted with rust in spots.

My Miller chart (211) tops out at 3/8" single pass for mix but only 1/4" for CO2. I would have expected at least as high of a max with CO2 if it has better penetration.

Ken