Welding Tips and Tricks

Sounds like a stupid question as I am obviously missing some info on how fcaw works. As you might be able to tell by some of my posts, I am not a seasoned welder. One thing I can't, for the life of me, figure out the relationship between volts and amps while running FCAW.

What I am struggling with is mainly the voltage requirements for FCAW (Shieldcore 15 0.9mm). I use solid wire (0.9mm) at work and pretty much everything I weld is 2mm or 3mm sheet/box, so settings never change, just technique.

Browsing CIG's product manual, and millers welding calculator I noticed there was a huge difference in voltage requirements, even though the current remains largely the same (When comparing solid wire to gasless wire). For example for 6mm steel it is recommended to run around 22-25V for 170-190A with 0.9mm solid wire, while gasless wire recommends only 15-16V for the same current (170-190A).

Where I am stumped is here. I know this might be obvious to most, and I'm probably overlooking some fundamental but here goes. My unimig 180 had a voltage range (i think) from around 15V-22V. My CIG has something like 15-20v. If i was to run the 0.9mm gasless I have here on the 15v setting, and tried to weld 6mm steel it plain wouldn't work. When I weld 4mm here at home I have it on its max voltage and it still seems a little cold, and needs a nice weave to build up heat (Thats 135A/20.5V from what the machine's manual says).

Where am i backwards here. I am obviously missing something. Does Polarity have an effect on voltage? Thats all I can think of off the top of my head.

Volts and amps have a direct relationship with ohms of resistance. Ohms law. Probably has something to do with the change in resistance due to conductivity of the puddle, the flux coating, or the gas shielding.

Gasless wire is "cored" wire. There's flux inside, so for a given inch of a given wire size, you have less metal volume in that inch; The balance is flux.

This changes the equation; Ignoring the flux, burning an 0.045 flux wire might be electrically equivalent to burning a solid 0.035 at the same "inches per minute."

Steve S

Are you running the correct polarity for fcaw?

If polarity is correct, and your machine is maxed out on voltage, and the bead is tall, rope like, and narrow - dial down your wire feed speed until it runs correctly.

Yes, the polarity is set up for gasless welding at home (DCEN), normally i juts turn the voltage to max and fiddle with the wire speed until it sizzles, and doesn't spatter. Depending on travel speed and technique it works well for 2.5-4mm steel, nice smooth bead and good penetration. I was just puzzled at the low voltages recommended for gasless wire from the manual.

For shits and giggles I set up my machine to the miller calculator/cigweld recommended settings for 3mm steel sheet which is 14.5v , set the feed to 190 ipm as they recommend and it was impossible to weld with, the gun was stuttering so hard, and pushing my hand everywhere. I turn it up to 3 (18.5V) instead of 1 on the voltage and it runs fine at 190 ipm...... What just struck me as odd was at work, when i set the machine to run gasless at work, and i select 14V as the wire recommends for 135A at 180ipm, the readout displays 55 Amps.....and its too cold.

I just find it odd that the one time I actually look at the supposed settings and measure wire feed i get a horrid weld, and when i just turn the voltage up to max and tune the feed by sound, it works wonders. I might try actually educate myself a little in the wonders of electricity, so when i see 14v at 140A (when my machine puts out 135A at 20.5v) i don't have a brain fart and pass out.

Funnily enough I have a wia 150s mig, a dial for wire speed and 2 switches marked 1, 2 and 3,4.
I have tried using the info on the wire cover, but keep going back to running a practice bead on scrap the same thickness as the job and getting that frying bacon sound and fine tuning until I get the bead shape and penetration I need, which may or may not resemble anything written on the cover.
Stone age simple, like me.
One day I'll buy something Noah didnt use to build the ark and has spray transfer.
So Vincenzo just use the settings as a guide and keep on doing what you're doing if it works.