At what thickness would you change from Argon mix to pure CO2?

[visor_down]

Hi all

I mainly weld thin stuff and have a 5%CO2/Argon mix for this, I need to do a few bits using thicker stuff, would the current mix be OK for this or do you have to use a higher content of CO2 or even pure CO2 when welding 3-8mm?
Where would you consider the cut off to be in terms of thickness for 5%CO2/Argon mix?
Part of what I need to do is join 8mm round bar (which i will bevel) and weld some 10swg weldmesh on it.

Although i don't have any 8mm bar/sheet stuff to do in the immediate future would be handy to know if it could be done with the mixed gas.
Welder goes up to 215 amps which I think is about 7-8mm so just interested to see where the gas becomes the limiting factor.

Would there be a need to increase the flow of the gas on the thicker stuff ? (usually run at about 10lpm on thin stuff)

Cheers
visor_down

 

[the snooper]

Stick with your current gas and flow rate

 

[Hitch]

I'd just stick with your 5% mix. Changing to a 20% mix wouldnt be of any real benefit on such a job.

 

[dannyp]

use the gas that's right for most of what you do, just adjust technique to compensate where needed.

at no point would I change to pure co2 as you cant spray. and I like spray transfer

 

[Andy south east]

I agree. I 5% for all my work. Ranging from 1.5mm right through to 12mm. Although if your going any thicker argon heavy will be a better and cheaper overall.

 

[Ed.]

The gas you are currently using is fine, 3-8mm is light fabrication, your welder's capabilty will have a greater influence on whether you get good penetration or not (ie; can it put out enough amps for 8mm?). I weld easily up to 16mm plate with a 93,5,2 mix. Argo heavy would be a better choice for 11mm+ sort of thickness. If you do a lot of heavy plate 11mm+ then go to argo heavy, but 8mm round is not anything to concern you.

Cheers

Ed.

 

[backpurge]

Totally agree with the above, as has been said CO2 is not a good option for thicker material as you cannot use it in spray transfer which you will probably be using for owt over 5mm welded in the flat position and it generates loads of spatter at high amps