CO2 or CO2/Argon mix with MIG?

Should I use CO2 or a CO2/Argon mix with my MIG welder?

I was reading "The Welder's Handbook" last night hoping to pick up some MIG welding tips, and the author says to use CO2 with MIG welders because it "works better." That's all it says. It doesn't say why it works better or better in what way.
I've got a buddy who only uses CO2 with his MIG welder, but he told me he does it just because it's cheaper. I've always used a CO2/Argon mix because the gas supply place recommended it the first time I went in.
Which really is better? Why?
I'm welding mostly sheetmetal (body work and floor pan repairs) one car build at a time, so the cost of the gas isn't a huge factor. I just want whatever will give me the best weld.

I did a search, but if I missed this topic please just give me the link.

 

You can use both, they both work, but argon mix apparently gives a softer weld, which makes it easier to work with a hammer and dolly after.

Using C02 is actually recommended in an old Unitor welding book we have here, but I think that was published before argon mix became common.

 

Argon / CO2 gives you the quality weld. People used plain CO2 because of the cheaper cost / not quality. If it's just Mig short circut welding then 85/15% mix is great. If you start using MIG spray arc or spray transfer then you'll want 90/10 mix.

Rule of thumb - Plain CO2 is for Beer. Carl Hagan

 

If You Do Alot Of Overhead Work Use Helihum Instead Of Co2

 

I've used both and the mix is better, the CO2 has a lot of splatter with it.

 

My Lincoln recommended using what they called "C25." That's what the guy at the welding supply house said as well. I think that's 25% CO2 and 75% argon.

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Thanks to all. I'll stick with the mix.

 

Yep! stick with the mix. Co2 creates more spatter and without a heater unit attached to the welding machine it's colder temperature when used at a fast flow can freeze the bottle and the regulator. The argon in the mix gives the bead a better appearance, and has better weld characteristics. Bear in mind that MIG is a form of Low Hydrogen Welding, if you need to drastically shape your panels afer welding you may find they distort as a result of the tension in the welds. If you think this may be a problem, gas weld, using low carbon wire ( baling or tie wire ).

Get it HOT! hit it HARD!

 

Good board to go to...

http://www.hobartwelders.com/mboard/

Did a serch for C25 and:

http://www.hobartwelders.com/mboard/showthread.php?t=23068&highlight=C25

If you really look---you'll find more about which mixture is good for what etc...

Roadrat

 

c25 Or Bust

 

MIXED GAS !!! Been welding for years , from hot rod stuff to production . For what you guys need 75/25 would be the best all around gas mix, cool enuf for sheet metal and hot enuf for welding frames to get good penetration ....... for wire size on sheet metal us .025 for nice beads and good control , less heat with smaller wire ( no big stabing boogers like you get with the larger wire ....... for welding frams etc us .035 , to get good penetration (larger wire , more heat ) but still have the controll of your bead for nice welds .........

 

All I've ever used in my Lincoln SP100 (and in the Miller 250 out on 'da Farm) is C-25...a Mix of 75% Argon and 25% CO2...it's 'mo money, but gives the cleanest weld compared to straight Argon or the other mixes. I also use the Easy Grind alloy and .023" wire....for body work sheetmetal.

Hope this helps....

 

I use a 25% mix. I'm only a weekend welder, but from my experience the straight CO2 seems to splatter more.