Soot, soot and more soot???????

[cumbriasteve]

Hi All
I have managed to find a couple of threads re my problem but not really an answer...I don't think.

Portamig 235 with Co2...clean welds but spatter as expected, so I got a bottle of 95/5 argon co2, appears to weld nicer but the soot deposit is unreal, black and heavy, wipes away no problem but am sure it should not be there.

Am welding new steel, round and sq bar onto flat, ranging from 5 to 10 mm, flowrate is about 12 and machine settings about 75% power.

Any suggestions welcome

 

[slimjim]

is there an oily film on the steel?

 

[cumbriasteve]

Hi Jim

No, its very clean just a little bit of the grey mill coating but that never bothered it when I was using co2...I tend to think its a lack of gas but can hear the gas and it seems right as in the flow rate etc

 

[pedrobedro]

What wire are you using? I never heard of sooting round welds before and if your gas is good and the metal is clean you should have no problem.

 

[cumbriasteve]

The welder came without wire so I bought a role from a firm that advertises on Ebay, apparently they are the last wire producer in the UK (Sheffield).

Thought I was doing right to avoid the cheap imported stuff, still hope I have.

 

[malcolm]

Could you post a picture?

You would normally associate a brown covering with lack of shielding gas (caused by vaporised metal rusting). A black soot would generally be carbon getting hot and burning.

Is the reverse of the plate also free from paint and oil? And is there any paint or sealant nearby that could be getting hot and blowing away the shielding gas with carbony fumes?

 

[cumbriasteve]

Hi Malcolm, I had a fiddle with the gas flow today and got rid of 90% of the soot but am now blowing gas out like a compressor.

Nothing at all close to cause a problem, the metal is held in a grease free vice.... probably close to a perfect welding environment

Will have a play tomorrow afternoon and take some pictures of it.

 

[weldequip]

Voltage could be too high, try turning the power down a bit. You'd be better using a 20 gas mix aswell on that kind of thickness

 

[cumbriasteve]

Voltage could be too high, try turning the power down a bit. You'd be better using a 20 gas mix aswell on that kind of thickness

Will try that, think I may have to drop to a 20% mix when I have used up this bottle...Cheers Steve

 

[Sparkey]

Gasflow should be around 10 lpm for you Steve...at work i'm welding at 18-20 lpm, but hey! t'is not me who has to pay for the gas!
I have some soot too when the parts are very greasy!

 

[Robotstar5]

...at work i'm welding at 18-20 lpm, but hey! t'is not me who has to pay for the gas!

The welders (& tackers) at work won't be able to adjust flow rate soon, we are fitting anti-tamper flow regulators!

 

[cumbriasteve]

Thanks Sparkey, Yes I thought 10 lpm was about right but to no avail, still soots the weld, there is without a doubt no grease anywhere that could cause it.

Considering the exact same steel did not soot up with Co2 I am thinking it has to be the argon mix as previously mentioned, probably need to drop it to 80/20 for the thicker stuff and higher voltage range.

Beginning to think my 30 year old arc welder was not so bad after all.

 

[Ed.]

Have you checked that there are no gas leaks in the line and that the fittings are tight from the tank to the torch?

 

[cumbriasteve]

Hi Ed
Yes all connections as tight as a ducks rear end, been fiddling with flow and taking greater care on torch angle to ensure arc is in the gas shroud and its getting better....so looks like its a combination of me and incorrect gas flow.