[hemtran]

using thermal arc ultra flex wire feed ultraflex 1000 wired 460 volt 3 phase
90% argon - 10% co2 flow rate 25
settings 15.4 volts wire speed 350 (turn table 20) automatic welder

first 360` weld perfect no holes in weld sometimes need to reweld to make pass wider
do not change any setting
second pass - immediately begins weld as if no c02 ( crater hole weld like metal sponge)
tried higher concentrate of c02 no difference
tried fast turn table - lower voltage

Not sure what is the cause or remedy

welding torque converters since 1992

any suggestions would be greatly appreciated. Mark

[MinnesotaDave]

Did you verify that the right amount of co2 is actually coming out of the tip?

It's happened to a couple people I know - started leaking where the gun meets the machine - pulled out just enough.

Regardless - leak somewhere is my guess.

Oops, just re-read it - are you using a mixer?

[Braehill]

Mark,
I'm no expert on Mig welding first off, but there are folks here who are and maybe they'll chime in here.

Have you welded the second pass prior to this with sucess? Reason I ask is some welding wire is made for a single pass. I thought this was limited to fluxcore wire, but I'm not sure. I know sometimes there's porosity trapped in a weld that doesn't make it to the surface and maybe the second pass is actually bringing it to the surface from the first pass.

Just some thoughts.

Len

[Mike]

Welcome to the forum Mark.

[jwright650]

Sounds like your first pass is cooking some impurities out and when you try to run back over the first weld it can't handle all of the junk that has floated out of the first pass. Just a guess. Are you chipping the silicon islands off before attempting the second pass? We are assuming that you are using a solid wire due to the voltage mentioned and not a flux cored wire. You mentioned 90/10 gas mix....there are some E71 FC wires that use that gas also.