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Pirosity

JeepFreak21

NAXJA Forum User
Location
Cameron Park, CA
Alright, so all the sudden I've got wicked pirosity with my Millermatic 175 (Mig). I didn't touch the regulator, the tank is full of gas (75/25), the tip is free from obstruction, I can hear the gas flowing, and the metal is prepped (I've tried several different pieces). Everything was flowing great, then, all of the sudden, I can't get a decent weld to save my life; crazy pirosity. I checked the gas hose for leaks the best I could without a spray bottle. What should I be looking at now?
Thanks,
Billy
 
filler metal issues? its rare, but it does happen. you could swap a different spool on. also check where your mig gun plugs into the wire feed and make sure things there are all buttoned up. and i know you said you didnt touch the regulator, but what is your flow rate?
 
porosity can result from impure metals being welded too, not just the wire. i have never had bad (or no) flux cause porosity. usually it just screws up the bead or won't weld at all, never mind having to worry about it being porous. i would change the wire, i think.
 
porosity can result from impure metals being welded too, not just the wire. i have never had bad (or no) flux cause porosity. usually it just screws up the bead or won't weld at all, never mind having to worry about it being porous. i would change the wire, i think.

the reason i didn't mention that was he said he tried on multiple pieces... of course i suppose it could all be from the same big piece or something.
 
filler metal issues? its rare, but it does happen. you could swap a different spool on. also check where your mig gun plugs into the wire feed and make sure things there are all buttoned up. and i know you said you didnt touch the regulator, but what is your flow rate?

I'm right in the middle of a ~10lb spool. I'm sure this makes it less likely, but still possible perhaps? I think my flow rate was at about 22 cfm (cfm?), but I've now tried it everywhere from 10 to 35.
Thanks,
Billy
 
porosity can result from impure metals being welded too, not just the wire. i have never had bad (or no) flux cause porosity. usually it just screws up the bead or won't weld at all, never mind having to worry about it being porous. i would change the wire, i think.

the reason i didn't mention that was he said he tried on multiple pieces... of course i suppose it could all be from the same big piece or something.

Yeah, I tried several different pieces from different sources. I even tried welding over and right next to the nice beads I did the week before.
dunno.gif

Thanks,
Billy
 
hmm this is weird. a long piece of wire could have been drawn from the same vat of molten steel that had a non-uniform composition :dunno: it's a long shot. i still say not the flux. porosity stems from impure metals. and if metals you know welded fine otherwise aren't welding fine... i say it's likely the wire. i personally haven't ever had a really porous weld, but i've seen it a lot. it's really common in cheap aluminums. can't say i've ever seen a porous weld in steel though.
 
hmm this is weird. a long piece of wire could have been drawn from the same vat of molten steel that had a non-uniform composition :dunno: it's a long shot. i still say not the flux. porosity stems from impure metals. and if metals you know welded fine otherwise aren't welding fine... i say it's likely the wire. i personally haven't ever had a really porous weld, but i've seen it a lot. it's really common in cheap aluminums. can't say i've ever seen a porous weld in steel though.

porosity also stems from reactive gasses infiltrating the sheilding gas atmosphere. i would keep your flow at 25-30 cfm; that is pretty standard flow for mig. if you do have a break in the lines somewhere it is possible that you could be pulling outside air into the lines(venturi effect) that is why i suggested checking the gun hookup, that is a prime candidate for that. what wire are you running(manufacturer)? is you porosity linear (longitudinal bubble lines down the center) or is it more of a massive porosity everywhere? pics would be helpful also.

G
 
Can I ask the obvious?
Is this a new bottle? Or are you using flux core?
Change your spool out if it is flux core, or take the bottle back if you just
had it refilled.
 
hmm this is weird. a long piece of wire could have been drawn from the same vat of molten steel that had a non-uniform composition
dunno.gif
it's a long shot. i still say not the flux. porosity stems from impure metals. and if metals you know welded fine otherwise aren't welding fine... i say it's likely the wire. i personally haven't ever had a really porous weld, but i've seen it a lot. it's really common in cheap aluminums. can't say i've ever seen a porous weld in steel though.

porosity also stems from reactive gasses infiltrating the sheilding gas atmosphere. i would keep your flow at 25-30 cfm; that is pretty standard flow for mig. if you do have a break in the lines somewhere it is possible that you could be pulling outside air into the lines(venturi effect) that is why i suggested checking the gun hookup, that is a prime candidate for that. what wire are you running(manufacturer)? is you porosity linear (longitudinal bubble lines down the center) or is it more of a massive porosity everywhere? pics would be helpful also.

G

Can I ask the obvious?
Is this a new bottle? Or are you using flux core?
Change your spool out if it is flux core, or take the bottle back if you just
had it refilled.

The pirosity is everywhere, not just down the middle. I'll get some pics tomorrow hopefully.

It's not a new bottle and the wire is Lincoln SuperArch L-56 .030. The gas is 75/25.

I'm thinking it's gotta be a gas leak, but I can still hear the gas flowing well at the tip. If I crank up the CFM, it would just increase the venturi, huh? I don't see any other causes for leaks, but I'm going to get a spray bottle so I can test it better.

Thanks for the advice guys.
Billy
 
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