tungsten exploding

[shawn]

i was welding a catalytic converter to the exhaust pipe on my jeep and the tungsten keep exploding on me. what would cause that? i'm using 2% thoriated and have the argon running about 15lpm

[performance]

#1) 15 lpm is probably way to much, turn it down to 7. Make sure you hear it coming out and nothing is kinked.

#2) You have your polarity reversed. This will vaporize an electrode given the right conditions. Your torch should be negative.

[performance]

#1) 15 lpm is probably way to much, turn it down to 7. Make sure you hear it coming out and nothing is kinked.

#2) You have your polarity reversed. This will vaporize an electrode given the right conditions. Your torch should be negative.

#3) You are using a mixed shielding gas with C02 in it. Use Argon only. Its possible to have a contaminated tank.

These are the three possibilities that come to mind.

[shawn]

i'm using 100% argon.

why would the tungsten be blowing up now when it was welding fine with just the exhaust pipe? i had to add in a section of pipe to move the cat further back and it welded fine but when i added the cat is when the tungsten started exploding

[shawn]

so i should be welding with the torch in the negative slow all the time? thought that was just for aluminum

[Rodsmachineshop]

I got a bad argon once destroys your electrode and 15 lpm is way to hi.

[performance]

AC is for aluminum, not DC, though a highly experienced tig welder can use DC + for aluminum with a mix of helium and argon, no DC current is great with aluminum.

DC+ will blow through the tungsten, especially if it is small tungsten as the electrode gets very hot. To weld with it, you need large tungsten to weld with very low amps.

I believe you have a PowerUltra, and it is not designed for aluminum.

[shawn]

ya i have the powerultra and no i'm not trying to weld aluminum. so lemme make sure i got this right. for welding any metal with a dc tig my torch should be in the negative slot and my ground should be in the positive?

[performance]

That's correct. In the manual, there was a misprint...my fault actually, not through ignorance but from weariness.

negative for torch, positive for earth/work clamp.

[shawn]

ok so i hooked it up the way you suggested and all it does is burn my tungsten up. turns my nice sharp point into a huge ball within a second or 2

[performance]

Can you post a pic of your setup? It seems that your tungsten was already coming apart. Plasma cutting and tig polarity are both the same. Look it up...Tig torch polarity is always DCEN, straight polarity. Your torch should be in the right jack and not the left.

[shawn]

that's how i had it setup originally then tried it the other way when you suggested i had it wrong. the units been malfunctioning for the past week so maybe the tungsten exploding is just another problem with it because the plasma is acting up as well. alex told me to send it back at the end of the week or beginning of the next so it'll be in the mail soon.

my new mig will be in tomorrow. can't wait to try it out since the tigs been acting up i haven't been able to finish any projects

[performance]

Shawn,

I suggested you check the polarity. Read again. I did not tell you to change it but to check it. TIG is always going to be DCEN. On the PU, there is only workpiece and torch designation, which is same as the recommedations I gave you with the torch jack being negative.

Nothing the welder could do would cause the tungsten to explode, unless there is not any shielding gas.

What size tungsten and amperage are you using? The only other thing that would rapidly deplete the tungsten is lack of shielding gas. Are you sure you are getting good flow from the regulator? Is the ball holding steady while you are welding?

I have also had a lot of reports lately( as Rod confirmed) of bad or contaminated cylinders. This is a possibility. I have had a few guys swear up and down it was the machines' fault, until they went ahead and changed out their "pure" argon, for another bottle. If the bottle wasn't properly vacuumed, the argon and argon co2 bottles are the same and they can sometimes be mislabled, cross filled or whatever, instantly consuming the electrode.

[shawn]

it welded fine for about 15 hours then when i went to weld the cat on is when i started having problems. the only thing i can think of is maybe the cat is made out of stainless. would that cause the tungsten to blow up?

[performance]

No, but the cat could have a lot of co2 trapped in it. Try some other metals. This will tell the tale. But a contaminated tank can work fine for a while then mess up, keep in mind that just as with any other "mixture" of gases, the gases can settle out for a while when they are first used, and you may only get pure argon for a while... Just a theory.