weld porosity issues

[rattle_snake]

Recently been having porosity issues with MIG. Have a fair amount of time on machine now, not sure what has happened. Checked all the usual suspects, but cannot find anything wrong to correct. Base metal clean as possible. Stuck at this point cannot weld anything that matters.

Miller 211 on 220v, Hobart ES70-6 0.030" C25 gas, mild steel.

I think I have ruled out base metal contamination, or contamination from flap wheel or grinder. Clean fresh ground metal. tested on multiple scraps. same result on un-ground mill scale.

Adjusting C25 flow has some effect, but anything from 15 to 40 CFH all have unacceptable porosity. I usually set at 20-25.

Adjusting voltage or wire speed outside of normal range also makes thing worse.

New tips. Gas passages clean. Seems to flow fine, same as always. Checked hose from tank to machine, tight. Tried different C25 tank, same result. O-rings at drive look good. Disassembled gun, don't see any issues.

Seems like this is a shielding gas issue, but not sure what to do next.
Went through this list
https://www.thefabricator.com/thefa...ing/22-possible-causes-of-weld-metal-porosity

Ideas? Suggestions?

 

[hefnerconstructionlc]

You don't have a fan or window blowing your shielding gas away do you?

 

[rattle_snake]

No wind, fan, A/C or other disturbance. Same environment. No change in tip angle, distance.
Issue seemed to start after welding on frame that had been undercoated. I cleaned it very well with solvents. Assumed is was base metal contamination, but doesn't appear so.

 

[GaryM909]

Maybe a leak between the flow meter and the machine.

 

[hefnerconstructionlc]

Man that is weird sounds like you have went through all things. Work clamp tight, all fittings to machine tight? That makes them act weird. I wonder if the heavy solvents leached into the plastic or something. If you changed the tips and cleaned the gun, you would think, it would rule those items out.

 

[tarbellb]

Double check your roller fed speeds, Miller has that quick lock system that can be overlooked sometimes.

 

[matt_i]

Its a long shot but open the case while disconnected from power and check the internal gas line fittings between the back port to gas valve and to and the front port where the gun plugs in (you get the idea, I don't know exactly what's inside of it) A compromised internal hose/tube/fitting would result in inert gas loss.

 

[rustyjames]

I would try lowering the gas to 15 and see what happens. I've had this happen to me before and that cured it. That's providing you have no draft in the work area.

 

[east_tn_emc]

Might consider that your shielding gas is contaminated....did it start happening after changing bottles of gas? I see you tried another bottle, but we’re they filled at the same time and location? A bit of a reach, but seems that all other possibilities were covered other than bad gas.

 

[The Cobbler]

^^ there was just a thread on here with contaminated gas, and the lower the tank got, the worse it got.

 

[Jlarson]

New spool of wire or has it been sitting out, or in the machine for a while?

 

[PugetDude]

I experienced the same thing, thought it was a breeze blowing my shielding gas. Played with pressures, no change so I started investigating...
Took the nozzle off, noticed the gas orifices in the gun were a bit mungy, probably residue from nozzle gel. Wiped everything down with denatured alcohol, hit it with a shot of air and it's welding fine now. (well, my welds still look like ****, but it's not the welder now)

 

[MP&C]

How humid is your shop? May want to check the wire spool for rust accumulation.

 

[king nero]

gas diffuser on the torch OK?

 

[BD1]

WOW ! You did everything imaginable and tried different tank.
Different wire is all that's left. I sure hope you let us know what caused it .

 

[zmotorsports]

Sounds like you've gone through much of it already Justin.

It certainly sounds like gas related but and possible contamination but couple other things to check.

How is the spool of wire? Is the wire tangled or corroded to the point of having a hard time coming off the spool?

Drive wheel tension. I've seen too much deform the wire and cause fish-biting as it's coming through the liner and the contact tip creating uneven weld deposition. I've also seen not enough drive wheel tension and not pulling the wire off the spool evenly.

For setting up drive wheel tension my procedure is to back off the tension to where the drive wheels slip and don't progress any wire. Then rest the gun tip/nozzle on a flat surface (floor or workbench). With the ground disconnected I squeeze the trigger and then tighten the tension on the drive wheel to where it just lifts the gun off of the work surface. This method has served me well for many years to ensure enough tension to pull the wire but not so much tension as to to deform the wire.

 

[C91x]

I have the same welder. Before I purchased I tried to find any and all reviews I could. I remember one youtube video where the guy had the same issue, sent it to Miller and they told him his nozzle was bad and that was changing the gas envelope.

I'll try to find it.

 

[C91x]

Miller Nozzle

 

[TS3g]

Miller Nozzle

Interesting video, thank you C91x! My 211 has been welding like garbage as of late, and has started gassing out randomly as well. I still have the original nozzle on it since it appeared to be fine. I'll definitely change it out the next time I use the machine.

 

[BigMike782]

Is the power pin of the MIG GUN fully seated in the drive housing?

 

[rattle_snake]

Miller Nozzle

Thanks Clint and everyone for the feedback and help. This is really a great place to share knowledge like this.

So the nozzle was the issue, very obvious once I looked. I hammered the ring back down to get proper tip stick-out, now porosity issues are gone. Time for a new nozzle or 3.

brass ring is way down inside the tip

Tip stick out was way past what it should be, gas envelope disturbed.

 

[The Cobbler]

GJ to the rescue again! A wealth of information here

 

[MoonRise]

Good find Clint!

Glad to hear you got things working again Justin.

 

[koditten]

Did you really weld with that much tip protruding beyond the cup?!