Stainless mig welding

[Carpenter84]

I only ever tig weld stainless. I recently did a very large fixture job which resulted in a solid week of stainless tig welding. Turns out that same job is coming up again in December. I know you can mig weld stainless. I need to do that next time to cut the weld time down.
Has anyone done enough stainless mig welding to offer any suggestions or opinions?

I am running an old dinosaur Airco large transformer multi-process machine. It’s a big old beast that I have Frankensteined into a half decent production machine. Capable of around 160 amps DC mig. I also have the matching high frequency unit.
I have any and every gas and accessory available at the “order desk”.

So, who’s done it? And what do I need to know?
I’ll ask the gas supplier what gas I need. I’m very familiar with my machine and every type of welding it’s capable of - but I’ve never mig welded stainless. I know cleanliness is going to be key. I’ll also ask the supplier what wire to use.

I’m looking for more experience based suggestions. Is there a certain technique to use? Is there anything I need to watch for? Are there certain products I should have on hand?
Believe the stainless is 304. It will be coming in 6mm sheet (form bent), 1/2” & 5/8” plate I will machine to necessary dimensions. The last order tig welded just fine (as fine as a butcher was capable of…) but I’m a slooowww tig welder….
Thanks

[Terrywerm]

I have done a small amount of MIG welding on stainless but a lot of TIG which is just slow by nature, but a much higher quality weld in my opinion.


Anyway, the little bit of stainless MIG that I've done is not enough to qualify me to really say much on the subject. I can say that it would be faster, but that is about it. 


 


 

[Carpenter84]

This is by no means structural or pipe welding. They are assembly fixtures for the auto industry. Likely to be abused and welded back together countless times.

[4GSR]

I recall they use 308 wire to MIG 300 series stainless with.  Speeds, feeds, voltage, play with until you get something that works. Follow the same as you do for steel and adjust accordingly.  High frequency not needed.  Practice on scrap until you get something that works.  Sorry I can't say much more than that.

[Carpenter84]

I recall they use 308 wire to MIG 300 series stainless with.  Speeds, feeds, voltage, play with until you get something that works. Follow the same as you do for steel and adjust accordingly.  High frequency not needed.  Practice on scrap until you get something that works.  Sorry I can't say much more than that.

Ok, that's fine.
But what I'm understanding is there isn't any major difference to mild steel? Figure out your settings, point and shoot? No special consumables (aside from gas and wire), or accessories?

[4GSR]

That's correct. nothing special other than the wire. No change in your gas either.  Now, if you want to whine a little, there may be a slightly different gas from your common 75/25 that may be recommended and available.

[Carpenter84]

That's correct. nothing special other than the wire. No change in your gas either.  Now, if you want to whine a little, there may be a slightly different gas from your common 75/25 that may be recommended and available.

Really! I read it has to have carbon dioxide.

[Carpenter84]

I'll likely replace my tips and diffuser/nozel. Should I replace my liner too? For cleanliness?

[4GSR]

"I'll likely replace my tips and diffuser/nozel. Should I replace my liner too? For cleanliness?"

I wouldn't worry about it unless it's needed. I'm no expert on the gas.  Try it with what you have first.  If it's not working, then change gas supply. Diffuser/nozzle/liner should not make a difference unless its bad to begin with.

[Carpenter84]

Diffuser/nozzle/liner should not make a difference unless its bad to begin with.

Yeahhhhhh...

[Carpenter84]

Thanks for the info, Ken. Appreciated.

[PJB]

No hands on experience here MIG-ing SS Shawn but I would think MIG will put a lot more heat in compared to TIG and in stainless that can be “fun” times. 


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[Carpenter84]

Yes, MIG puts out a lot more heat... However, so do I when I tig weld...  lol