Hobart 170 porosity issue weird !!!

[onyx]

Hello thought I'd try here
problem is it welds great until something gets warm in the machine. Then it welds like it has no gas. It does !!! The thinker the material the higher heat setting makes it happen faster. Let it cool down and good to go until it gets warm again. I know not much info. This unit is older mid 1990's

Thank you

[ryanjones2150]

What wire, shielding gas and settings? Explain your weldment too please.

[onyx]

Hello I should add that this started to occur on my last project welding 3/8 material. The welder has worked fine before this. Something has gone amiss. Ryanjones2150 I am welding 030 wire co2 argon mix on 3/8 mild steel. I feel like maybe I've over pushed this welder too much throughout the years. It just started about half way thru this project and will still weld fine until it gets heavily used or as I call it warm.
Thank you

[ryanjones2150]

Generally speaking, porosity is a shielding gas or a cleanliness issue. I'm guessing you're running solid wire? What brand? I have seen a few times inconsistencies in the lower end wires, like the junk from horrible freight.

[Noel]

I'm just throwing this out there but a weak gas solenoid is what I would suspect. A magnet with a weak coil? Sounds like its electrical field looses it strength and its allowing the solenoid to either partially or fully close impeding gas flow and coverage? I have an older Millermatic 135, giving me that problem on occasion. At least that's what I suspect? Well that's my guess.

[onyx]

Ryan good quality wire from local welding store Praxair. Yes solid. Again the issue seems heat related with the welder. Noel. I was wondering something along that line myself. I can hear the gas start for sure when it occurs, but I can't be sure while welding. I will try and source the coil out and attach a meter to it while welding to see if it changes as I weld. Thank you both for the imput. I'm ready to start another big project and hate to go buy a new welder. I'm having trouble with the reviews and issues that people are having with boards and such on new ones. This has been a great shop welder for me for a long time.

[elvis]

If you have a floating ball type flowmeter then it's easy to have someone watch that when you have the problem and see if your gas flow is dropping.

[onyx]

Elvis good point unfortunately I don't have that style. Thank you

[ryanjones2150]

When it starts to act up, pop the clamp on the feed motor so it's not pushing wire. Then you'll be able to flow gas without running wire out the tip. Even if you don't have a flowmeter, you can still see a fluctuation on the needle of a regulator if the flow rate is dropping off for some reason.

[onyx]

Sounds good I will try that. So what I'm hearing from you all is its more likely gas rather than transformer issue ?

[ryanjones2150]

I'm not a welding machine repair guy, but when I see porosity, I think metal contamination of some sort....be it the metal or the gas.

[aametalmaster]

Make sure you gun is pushed all the way into the drive casting. Loosen the wire clamp from the drive rolls and hold the gun to your ear and make sure its getting gas. Is there a cut in the gun cable? 3/8" metal with .030 wire. I thought I was the only one who did that ...Bob

[Noel]

Humble pie to that Sir. I was doing a Stainless job changed out a roll of wire and started experiencing problems. Yup, hadn't reseated the gun and cable far enough back in. Pressure would hold for the first inch or so and slowly go to crap.

Thanks for the memory.

On to my Sunday evening musings and over thinking.

-030 wire co2 argon mix on 3/8 mild steel.
-Hobart 170
-3/8" plate
Onyx...I'm going to offer up a plausible explanation as I did previously about the gas solenoid, but as always when I open my mouth words come out so work with me. What if I suggested that switching to .035 would solve that problem? It might some what.
I suggest you're trying to push that Hobart 170 to scream a thread of .030 fast enough to fill a weld deposit on 3/8 plate for which I would suspect will be at a risk to reaching the high end to a duty cycle capacity if you work er' steady?
You should share your settings? A picture would be great.
But think of it this way. You have enough argon in the mix to almost get that wire, and I'm sure you are, into a semi spray. I say semi because as the experts will tell you, you need a greater percentage of Argon and your on the small end of wire size to obtain current density to achieve it, an axial spray transition.
I'm sure however it looks like the droplets off the end of the wire appear to be streaming?
Now at the risk of loosing the audience to some deep theory, picture a tornado. At the top is the nozzle on the ground is the destruction.
During the process the wire short circuits, the current surges. Think about a few simple things in theory. That wire it's carbon steel. It's magnetic until it reaches temperatures upwards of 1200F. You have current flow you have magnetic fields. They form rings around and up much like the tornado. The wire hits the plate, the current surges (Slope) the rate of rise (Inductance) causes the wire tip to heat up, and the magnetic field strength is changing as heat build up increases, in the plate and on the wire.
The type of shielding gas effects the strength of the magnetic field and it's potential but it's ebb and flow causes the droplet if the wires tip gets hot enough to be pinched off. Until that current is lost it will squeeze droplets of molten metal over and over if set properly, the speed of which is controlled by setting on the machine, volts/wfs (amps), stick out and operator control to maintain it. As well position and inclination when welding or variations too changes when welding. A larger wire size is like a large log on the fire over a bunch of kindling.
I'm thinking out loud...you have the voltage set fairly high, the wire speed cranking and the wire is burning as fast as it's exiting the tip in which case, if your getting things done, that odd burp riding the edge of settings and wire size causes enough disruption when it happens that you get porosity. Hence why a larger wire size could offer greater arc stability and filling capacity on those 3/8" plates.
Good luck, lots of good advice.