General purpose mig gas - I'm confused!

[njc110381]

I've been searching the forum as well as doing a general internet search, and I'm still confused over what gas I should get? A friend of mine works for a gas supplier and gets good rates, so the world is my oyster from what I can gather. But which one do I need?

From what I can gather, CO2 helps penetration, argon stops the spatter and oxygen??? There's a pub gas thread - so is this ok? I don't know what to ask for!

I'll be using it with an R-Tech 250A mig to weld everything from thin sheet to 5mm, more occasionally. I'm sure it's been asked a million times, but I can't find a thread that really gives a solid answer!

 

[slim_boy_fat]

I think most use Argoshield [BOC] or a similar mix for mig [other brand suppliers are available ]

 

[Kent]

A light mix from BOC is what you should get

 

[Richard.]

Straight Co2 is the cheapest solution but runs hotter than argon mixes which in turn makes thin sheet a little more challenging . It doesn't run as clean and as you pointed out much more spattery . Argon mix is much nicer and cleaner. You should select your ratio depending on Common material type and thickness. Stainless runs best in 97.5% AR
Steel up to 5mm 95% Ar
Steel 5-10mm 85% AR and 10mm plus 80-75% AR. It's not an exact science and you can push the boundries but the higher the % of active gas the hotter it runs and deeper pen achievable. The active gas CO2 and O2 are needed for ferrite metals to offer wetting, penetration and smooth toe transition. The only time you'd weld with straight AR would be for aluminium.

 

[njc110381]

Thanks guys. I think it's going to be fairly simple for me to chop and change. Where my mate works, if they take in part filled bottles the staff are allowed to take them and empty them as long as they are returned fairly quickly. I've asked him to get me an 86/12/2 or close to it for now (spoke to him before I read Kent's comment), but can always raise the argon if I have trouble.

I'm thinking of running my first welds on fairly hefty metal. I found some 8mm sheet and a couple of offcuts of RSJ in the garden along with some 5mm box so I'll stick them together before I scrap it, and pick up some thinner stuff when I do. I haven't got much under 5mm "in stock".

 

[Welderpaul]

I wouldn't get too fussy about the precise mix if your cobbling stuff together. Any BOC Argoshield (light/Universal/Heavy) would do...or Air Products equivalent etc

 

[njc110381]

That's the sort of thing I like to hear! Being a complete novice it was seeming like the mix could be pretty vital. The last thing I want is to need more than one bottle.

 

[Kent]

Yes, Paul is correct you can use any
When I first started there was only co2! However get the correct one for your set and use rather than make do

 

[Paul G]

Quote Welderpaul "Any BOC Argoshield (light/Universal/Heavy) would do...or Air Products"


I get by using Hobbyweld 15. (i.e. universal)

Everything from an MX5 sill to a digger bucket tooth.

Paul G