Power Mig 255 Spray Transfer?

[Shadill]

Hi guys, I'm trying to achieve a nice spray transfer with my powermig 255, using .045 solid wire and praxair's stargold 66 gas, which has some helium in it (my lws recommended this gas for spray transfer), I'm welding 1/4' thick mild steel with mill scale still on, and the majority of the welds are fillets, anyway I am so close that I can taste it and just need some help. Currently the closest I'm getting to a spray transfer is with the welder settings at 26 volts and 220 wire speed, but it's still making some spatter and still not a nice hissing quiet clean spray.

Any help would be greatly appreciated, I'm trying to put off buying a larger 3 phase machine with a power source and separate feeder for as long as I possibly can.

[Dan]

Switch to a bottle of C10 (90ar/10 CO²) or 98/2 oxy shielding gas, and your unit should have no problem producing a solid spray with an .045 wire. Admittedly though an .035 wire might be a little better choice to go with for the out put power range of the PM 255 unit. I'm not stating the wire diameter reduction is required though. I definitely recommend switching to a gas mix that doesn't contain helium in it.

You should also take the time to remove the mill scale from the weld zone area. Not doing so, tends to corrupt the quality of the spray transfer arc.

[Shadill]

Thanks for the reply, I'll try to get some c-10 or c-5, I was told that .045 would be better because of the lower wire speed, I have to find a way to weld with the mil scale still on, it would just take too much time for the production type work I'm doing right now to grind it off

[MoonRise]

The 255 -can- do spray-transfer.

But too big of a wire and the 'wrong' gas and it can't.

0.045 plain steel wire transitions to spray-transfer at ~ 220A with 98-2 Ar-O2, ~200A with 95-5 Ar-O2, ~225 with 92-8 Ar-CO2 (aka C8), and ~240A with C15.

0.035 plain steel wire and you are looking at ~140-165A, ~155A, ~175A, and ~180A for those same gas mixes.

WIth 0.045 wire I think you need to turn the machine up a bit higher in WFS/amps to get into spray transfer, depending on the exact gas mix being used (if that gas mix even supports spray-transfer).

Lincoln wire catalog lists parameters for 0.045 L-56 (ER70S-6 wire) using C10 gas at 27V and ~285A.

0.035 L-56, C10 gas, 23V and ~195A.

[astrazzi]

Helium will act like CO2 in the sense that it is counter productive to producing a spray arc. Helium mixes are most commonly used when trying to achieve greater penetration and most common on Aluminum or Stainless. When welding fillets on .250 mild steel using the "spray arc transfer" mode I would select ER70S-6 .035 wire and C5 (95% AR/5% CO2) gas. Last I would slap the guy who recomended using helium mixes on .250 mild steel. Helium is really expensive right now.

[Matt_Maguire]

Originally Posted by Shadill

Thanks for the reply, I'll try to get some c-10 or c-5, I was told that .045 would be better because of the lower wire speed, I have to find a way to weld with the mil scale still on, it would just take too much time for the production type work I'm doing right now to grind it off

That wire size thing is true for short circuit but goes out the window with spray based on power supply. The 255 class will actually spray more lbs per hour with .035 vs .045 using carbon steel wires and stay together.

I gotta be a bit careful here because this is one of the reasons mig won't pre-qually for structural as you can burn off more can you can "stick" as you run deeper past the transition.

With .045 at 220ipm you are just at the bottom of spray and you will be running 200-220ish amps. That gives a burnoff of 4-5lbs per hr. With .035 at 220amps you are consuming 430-460ipm of wire and getting between 6-7lbs per hr burnoff. As you turn up the .035 past that 450ish ipm rate in a true spray, poor fusion (especially in "T" joints) can happen quickly.

A 255 doesn't have the poop really to spray .045 where it really likes to work (275-350amp).

Matt

[aevald]

Hello Shadill, I may be a bit late with this item, yet you might consider using a metal-core wire. Solid wires use a certain percentage of the power supply's available energy to melt the "solid" filler, a metal core wire has a thin metal sheath that encases powdered metal and melts more readily, requiring less overall energy to melt the wire and allowing for more energy to melt the base metal. They generally also work really well on materials that have a less than ideal surface condition. See if your LWS has some wire that they would be willing to allow you to demo. A little something else for you to consider. Good luck and best regards, Allan

[Shadill]

Thank you guys for all the useful information, I finally got my hands on some 95/5% mix and have it very close with .045 wire 26v, 210 wire speed, still getting some minimal but large diameter spatter at the start and towards the end of my welds. I may switch to .035 and see what happens.

It's pretty sad that no one locally even knows what the heck I'm talking about when I ask about spray transfer, I even talked to a welder who was welding spray, working at a scissor lift manufacturing plant all day long and he didn't even know what the difference was, he was just trained to weld that way. They use larger 3 phase machines, like deltawelds

What advantages are there to switching to a larger machine, like a deltaweld or idealarc with a separate wirefeeder? I have the option of connecting 3 phase to my building

[Silicon-based]

As others said, the main advantage is being able to run .045 wire in its ideal range, with a higher duty cycle.

You can also go up to a 350A-class machine without needing 3-phase power. This will not only give you more oomph, but also more functions such as run-in, burn-back and post-flow, which will improve your starts and stops. Most also have pulsed spray capability, which will give you more options.

John