Major issues with porosity in MIG welds

[JobeFabrications]

I've been having intermittent porosity issues and in the last week they have gotten horrible. I'm running a Millermatic 175 that I have had for several years now with no issues. Today I swapped out the gas and wire. The stinger is less than a year old, new tip, cup, etc. Still have major issues. Tonight I swapped the regulator out with a friends Miller 211. Tried his gas tank. Nothing worked. I then tried his welder...and no issues.

So my question is what could be wrong with my welder that would be causing these problems? I'm getting gas flow, no issues there. I recently switched to a magnetic ground clamp, but I put my old clamp on tonight and same problem.

All the steel is brand new and clean.

I'm at a loss and ready to just go buy a new welder.

Thoughts? I'm going nuts and in the middle of a big project. And this is a major issue as all of my furniture I make is bare steel with ground welds 75% of the time. No way to fill and hide the issues.

Thanks.

 

[W-Cummins]

Porosity is almost always caused by contamination of the weld. Looks like you have tried to elmiminate the most common causes. The only things I can see that may still be the problem are in your gun. Can you swap the gun with your budddy's gun? Could be **** in the liner or maybe a clogged up gas diffuser??

William....

 

[king nero]

porous lines or connectors, too few or too much gas, problems with you regulator (frozen? dirty?), your gun too far from the weld or incorrect positioning,
contact tip not in the middle of the outer tube, or the outer tube is full with splatter,
water lines (watercooled gun?) leak and evaporate in the gun, thus water in your melting pool => porosities, ...

 

[koditten]

Does the welder have a speed seletor switch? Hi and low range. I made this mistake once. Must have bumped this rocker switch. Took me all after noon to figure it out. I felt pretty stupid.

KO

 

[koditten]

You checked the ground cable at the welder? How about the whip power clamp at the welder?

You don't have a cieling fan on hi speed? I've had trouble with this one at times, I like to run my gas at the absolut minimal and the fan can blow the shielding gas away at times.

KO

 

[Doug Arthurs]

You haven't recently changed polarity have you? Maybe by accident or if you changed over to flux core for something.

 

[kf4zht]

I have a miller 175 and have the common issue where the lead to the gun pulls a little bit out of the body of the drive assembly. This causes the gas ports not to line up. It tends to happen after working on the gun or if you ever pull on the hose too hard. All it takes is 1/8" or so.

I would check this. The front lip must be flush with the cast part.

 

[aka Larry]

I'm not sure the cause, but it seem definitely related to an issue with the shielding gas. I'd try turning the cylinder off and see what happens. If it welds pretty much the same then you're not getting a good flow of gas when the cylinder is on.

 

[JobeFabrications]

Thanks for the tips guys...responces in no particular order...

The gun is less than 6 months old, properly seated as I've had that problem before. I'm getting flow just fine, tried different pressures, I can feel the gas coming out, all the ports are clean. I even tried another regulator, same problem. Polarity is correct, I never run flux core in this welder. I weld inside, no air flow, no fans, nothing blowing gas out. Running the same stick out and tip/cup position as I always have. I have changed nothing on this machine since the gun 6 months ago. Was running a 10 pound roll of wire, just changed the wire, have changed gas canisters, even from different welding supplys. All I can guess is something is wrong with the welder itself but I have no idea what it would be.

 

[ezzzzzzz]

Take it to Texas Welding Supply and let the service shop check it out. It will cost you a fee, plus parts if it's really broken, but they're the professionals.

 

[JobeFabrications]

That's who I shop and deal with, they are the best in town. And that is where my welder is going this afternoon. I just hate be down without a welder for any amount of time.

 

[theknurl]

contamination;
its either gas being diverted, deflected or turbulence in the nozzle
or rust on the wire

do you use wire lube?

 

[bullnerd]

Well, the presence of tiny cavities in a piece of welded metal is basically what Weld porosity is. I believe you will need to buy a new welder, as this has got spoilt and will not work anymore.

****!

Good luck Jobe.

 

[AndyA]

Make sure all your gas connections are tight. Look for cracked hoses. I'd bet you're drawing air into the shielding gas (think venturi).

Also dirty material will cause porosity. You said you used your buddy's machine. Was this on exactly the same material?

 

[welder4956]

I'm thinking a loose or damaged gas connection somewhere. Check all the fittings for tightness at the regulator, the gas solenoid, and the gun connection to the machine. Inspect the rubber o-ring on the end of the gun at the machine to make sure it is not damage. Then you might check for leaks in sections. Turn on the regulator and set to a normal flow rate, say about 25 cfh. Does the ball on the flowmeter rise or flutter with the gun trigger not pulled? If it does not, the line between the regulator and the gas solenoid is good. Loosen the drive roll tensioner so it does not feed wire when you pull the trigger, remove the contact tip, place your thumb over the hole for the contact tip and pull the trigger. Does the flowmeter ball rise? Can you hear the leak somewhere along the gun or inside the machine? It is possible that something could have been dropped on the gun causing damage to the gas line inside the covering. Inspect each end of the gun cable closely for damage. The gun cable is made with the gas and liner running through the center of the copper cable, as shown in this pic. You could have a leak inside the gun cable. You would think the gas would only leak out, but a leak also aspirates air to the inside of the gun.

 

[trbomax]

What gas mix are you useing? 75-25 runs much cleaner than 100% co2 100% argon will do what you describe too.

 

[Steroblan]

Look very carefully at what has changed just before the welds went bad. New wire? Try a new spool of wire and examine the new tip and make sure you installed the parts right. Check your stickout. Check all your variables carefully before you take it in.

 

[JobeFabrications]

Took my welder in for service, explained what was going on and they were stumped as well.

Got a call 2 hours later saying it was my nozzle! The stop inside the nozzle had broken loose and was letting air in the backside of the nozzle. Crazy! New nozzle and a clean bill of health on the diagnostics machine and we're back in business. They had never seen that problem before either.

 

[Keyblazer]

What gas mix are you useing? 75-25 runs much cleaner than 100% co2 100% argon will do what you describe too.

That was my thought too...
Are you sure your bottle has 75/25, because I mistakenly left my Argon bottle attached after doing some Aluminum..
The results of trying to MIG steel with Argon were horrible!

 

[kevin47]

You said it was "new steel"...Where'd you get it from...? Are you sure of the type...? It's not "free machining"...? Like a 1200 series...?

 

[welder4956]

Took my welder in for service, explained what was going on and they were stumped as well.

Got a call 2 hours later saying it was my nozzle! The stop inside the nozzle had broken loose and was letting air in the backside of the nozzle. Crazy! New nozzle and a clean bill of health on the diagnostics machine and we're back in business. They had never seen that problem before either.

Glad to hear you got it fixed! Happy welding!

 

[LG63]

I'd bet you're drawing air into the shielding gas (think venturi).

Looks like AndyA called this one. Impressive!

 

[theknurl]

Took my welder in for service, explained what was going on and they were stumped as well.

Got a call 2 hours later saying it was my nozzle! The stop inside the nozzle had broken loose and was letting air in the backside of the nozzle. Crazy! New nozzle and a clean bill of health on the diagnostics machine and we're back in business. They had never seen that problem before either.

what kind of gun are you using?

Twecos use 3 round wire snap rings to hold the nozzle on the insulator which threads onto the tip holder
the tip holder has the gas port in front of the insulator
there is no stop....in a Tweco

 

[black88coupe]

Cool! Glad you got it worked out.