One gas mix for spray & short circuit?

[drscotch]

I've always run C25 for my MIG work. I understand you need at least 80% Ar to run in spray mode. What impact would 80/20 have on short circuit mode? It would be tough to justify 2 bottles on hand to run each mode from time to time. Is there a mix that is a good compromise for both modes?

thanks

[fluxcore]

I've always run C25 for my MIG work. I understand you need at least 80% Ar to run in spray mode. What impact would 80/20 have on short circuit mode? It would be tough to justify 2 bottles on hand to run each mode from time to time. Is there a mix that is a good compromise for both modes?

thanks

I head 85 ar/15c

[MAC702]

Don't know about your particular machine. My PowCon, will run a good short-circuit with C-16, and also spray with it, but it's at the borderline and sometimes drops out of spray into globular transfer. So, I would say it's POSSIBLE with some machines. Worth experimenting maybe, but then if you can afford the experimenting, it might be just easier to get a second gas...

[HAWK]

I favor a 92% argon/8%CO2. The MM250 has plenty of power for a nice spray with this gas mix and will also run a "soft" short arc.

[burninbriar]

Whats a "soft" short arc ? If its not something easily explained its no problem becouse I dont have a mig any way. Just curious.

[Danny]

The ol MM 250 has a pretty sluggish weld puddle in short circuit transfer mode with C-25, and lowering the CO2 in the shielding gas content sure seems like its going to make it even more sluggish. I ve tried spray arcing an .035 solid wire with C-15 using a MM 250, and based on my experience I most definitely wouldn t recommend the gas mix as a spray mix for a MM 250. Heck, based on my experience the MM 250 struggles in spray transfer mode with 98/2 Oxy. Based on my experience, the MM 250 just wasnt/isn't a very good spray arc unit. Now, the MM 251 that has replaced it, is a very impressive spray arc unit. Heck, in the range that my MM 210 will spray arc, it is a far better unit then the old MM 250 too.

[HAWK]

Dan,

The MM250 had its problems and so did the first release of the MM251's. They would not run a rated duty cycle without shutting down way too soon. We had a a batch of 12 machines like that here in town. Miller replaced them no questions asked and all was fine from then on.

You are correct that the 98Ar/O2 will spray better in the MM250, but certainly won't yield much of a short arc. I suppose it's a 2 gas proposition or a different machine. This is easy for me to forget when using 400+ amp GMAW machines with variable inductance and all the goodies.

[HAWK]

Whats a "soft" short arc ? If its not something easily explained its no problem becouse I dont have a mig any way. Just curious.

burninbriar,

The arc does not have the distinct hard and crisp crackle of a standard GMAW setup using C25. The softer arc tends to wet the toes easier and yields a less convex bead profile. Penetration can become a problem with the lower CO2 content, but this is easily overcome with 250+ amp machines.

[burninbriar]

Ah-Ha : Thanks for the explanation Hawk, makes sence.