5% CO2 or 20%?????

[RogL]

I'm about to order my first refillable cylinder - we're using CO2 on my MIG course at college but I'd like less spatter.
Should I get 5% or 20% CO2/Argon for car body/chassis work, bearing in mind I'm newish to MIG welding?
I'm using a Supermig 180.
Any advice appreciated.

I'm also intending to use Adams gas, no rental, mid price on the spreadsheet, and they have a local supplier. Makes sense...?
My nearest Hobbyweld supplier is sadly too far away.
Cheers
Rog

 

[shenion]

5% will also have a few % of O2.

20% will be just Ar/Co2 mix.

They will work about the same for most uses. I use 75/25 as it is the standard here and I get nice clean welds and no problems on thin metal.

 

[backpurge]

In the UK 5%, 12% and 20% "standard" mild steel MIG welding gases all contain 2% oxygen as well

As Scott says, a 5% mix will be best for car bodywork

 

[pedrobedro]

Higher co2 for thicker material, go for 5% for car bodywork. Not all suppliers put O2 in the mix but it doesn't hurt to have it in there it is supposed to help wet out (flatten) the weld so more for appearance than anything. 20% is like the old BOC argoshield heavy which is one step up from pure co2

 

[Daz1968]

I went with 5% for car bodywork its what was recommended for thinner material, same mix as argoshield light

 

[matt1978]

The "real" reason there is Oxygen in the mixes is because they use crude Argon for cheapness and not the high purity stuff as is for Tig. The gas suppliers then say its there for a benefit but its all smoke and mirrors.

But around 5-7% Co2 will do you fine.

 

[RogL]

In the UK 5%, 12% and 20% "standard" mild steel MIG welding gases all contain 2% oxygen as well

As Scott says, a 5% mix will be best for car bodywork

Thanks very much for the replies - that'll be 5% then and we're good to go!

Cheers
Rog

 

[Llama]

The "real" reason there is Oxygen in the mixes is because they use crude Argon for cheapness and not the high purity stuff as is for Tig. The gas suppliers then say its there for a benefit but its all smoke and mirrors.

But around 5-7% Co2 will do you fine.

I always thought it was for stainless MIG, as you can't run pure argon with MIG but CO2 causes carbon buildup or something

Or have I been sucked in like you say

 

[matt1978]

The specific Ar/Co2 mixes for Stainless are never more than 3% Co2 (dependant on supplier) usually 2-2.5% Co2 and there in no Oxygen inc in the Ar/Co2 but you can also buy a Ar/Oxygen mix for Stainless which has 2% Oxy 98% Ar

 

[backpurge]

The "real" reason there is Oxygen in the mixes is because they use crude Argon for cheapness and not the high purity stuff as is for Tig. The gas suppliers then say its there for a benefit but its all smoke and mirrors.

But around 5-7% Co2 will do you fine.

That's not strictly true Matt

 

[matt1978]

In what way?

 

[backpurge]

I know of a least one major gas company who's mild steel MAG gases are a genuine 3 part mix

 

[matt1978]

I wasn't saying that they are not really 3 component gases ie Ar/Co2/O I was just saying their is a bit of jiggery pokery with regard to the benefit to the customer as to why it has Oxy in. It's cheaper for the gas company to use crude Argon to produce the mix and a product of that is that included Oxygen.