Weird TIG arc instability

I have had a similar problem over the years. I find it has to do with the quality and type of tungstens and how happy your high frequency unit is.

Try Cold Scratching.

Every time a TIG arc is created, a certain amount of vaporized metal ions are trapped in the arc stream. When the arc collapses, these ions will cling to the surface of the tungsten, creating a very thin layer of metal oxides. This layer of oxides acts as a perfect insulator, preventing the arc from re-initiating.

By scratching the tungsten on a piece of metal with no current running, you can break this oxide, thus allowing the arc to initiate.

Get in the habit of cold scratching before each weld and you should have much improved arc starting.

BTW try switching to Lanthanated tungstens for all AC and DC TIG.

Ernie,

Are you saying that lanthanated tungsten are preferred over regular tungsten? I am trying to learn something here.

Thanks

AH!!! That explains a similar problem Iv been having. THANKS!!

I did at your advice year or so ago..makes a hell of a difference.

Gunner

"I think this is because of your belief in biological Marxism. As a genetic communist you feel that noticing behavioural patterns relating to race would cause a conflict with your belief in biological Marxism." Big Pete, famous Usenet Racist

2% lanthanated (blue) is suppose to be the "best" for DC.

i experienced your issue using blue. taking off the cup i noticed burn marks on the copper collet... odd, seems as if the arc was jumping off the collet and skinning down the outside of the tungsten. i cant figure it out. i did however notice that more gas flow seems to make it happen less....

also make sure your gas line is purged and you have some argon pre flow set to purge the weld area (mine is set at 1 sec. preflow)

Re place the cup.

Yes.

2% Thoriated (red) tungstens are "ok", but only OK, not great. Plus Thoria dust is a radioactive alpha emitter, which may or may not cause lung cancer. Also Thoriated tungstens only work well on DC. With AC they erode rapidly and make for an erratic arc.

Pure (green) tungstens, the traditional choice for AC TIG, ...SUCK. Yep they just plain suck eggs. Don't waste money on them.

1% (black), 1.5% (gold) or 2% (blue) Lanthanated tungstens will work on AC or DC and do both better than almost any other tungsten out there.

The only kind of tungsten, other than lanthanated, that I buy are zirconiated (brown). Zirconiated tungstens are specifically for very high amperage AC.

The only other AC/DC tungsten available is Ceriated (orange), but they are more for very low amperage work. At higher amperages they don't work so well.

Thanks, Ernie.

Doggone, I wish that you would write a book. Anyone else wish this? I am standing back for the flood of replies.

"Ernie Leimkuhler" wrote

I ordered the 1.5% in 2 sizes and it makes my welds look like I know what I'm doing. I also got a box of 1/16 ceriated, but havent welded anything really thin yet. What about the percentages? Why would you chose one over the others?

Higher percentages of doping agents should increase the heat resistance of the electrodes.

I did, years ago, about welding for theatrical scene construction. I couldn't get a single publisher interested.

If I do write a book it will be self published.

Viva La Internet.

Had something similar going on. Believe it is poor contact between the tungsten and the copper collet. I buff the oxide off the tungsten with a wire wheel-seems to help greatly. using the more expensive polished finish tungsten would also help.