Welding Tips and Tricks

What causes frosty tungsten and the little nodules to form on the tip of the tungsten?

I don’t have an inverter machine so should I be balling my tungsten or can I start with just the tapered tip and let it ball up as I go? I use 2% ceriated tungsten at the moment. I use an older Syncro 250.

With what I’m welding, I use a 3/32 tungsten, #5 cup and pure Argon. My settings are generally 70 Amps, 7 on the AC balance, which is supposed to be around 70% EN cleaning from what I have read was on this machine.

More than not I end up with more of a flattened tip on the tungsten that is not shiny or smooth.

Maybe you can help me understand what needs to be adjusted.

Thanks!

Most folks I know that run a transformer machine use a pure tungsten (Green). The nodules are due to the cleaning action tearing at your tungsten.

i would have thought that if the machine has AC balance then the old "use pure tungsten with transformer" rule would not apply.
i would be inclined to just go with what works. if you do a point and find it just blows away rather fast then i would ball the tungsten. i would use a flattened tip.

the nodules i don't know the cause, i've had it a bit myself. possibly due to tungsten type. i would try a 2% Lanthanated as a good all rounder.

Pure tung is an economical choice and doesn't stand up to the arc very well. Zirconiated tung is usually recommended for AL welding with a transformer machine, and it does stand up to the arc quite well as long as you have the appropriate dia for the job.
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In summary, follow these three recommendations:

Use a pure tungsten or zirconiated tungsten electrode when AC welding aluminum. Don't use a 2 percent thoriated tungsten electrode.
Make sure you use a tungsten electrode large enough in diameter to carry the welding current you plan to use. Remember that AC welding requires larger–diameter tungsten electrodes.
Let the tungsten form a round ball on the end. This will happen naturally while welding.

From an article in the The Fabricator.com

I run the same machine and used pure tungsten for ever. I was burning back the tip bad (learning curve being self taught) so I turned up the penetration to 9.
The tip lasts longer (shiny ball) but they still deteriorate faster than I wanted. I tried 2% Lanth per watching Jody's testing and they seem to hold up better. I still keep pure tungsten on hand.

I run a transformer machine (Sync 250) and 2% lanthanated tungstens work just fine on AC.

I wouldn't worry about the nodules that form on the end, it's just the way it is. I think it's just a version of the "balling" that you get with pure tungsten, which I believe is caused by the "electrode positive" portion of the current melting the tungsten. All other things being equal, if you move your AC balance toward more EN and less EP, you'll get less balling/nodules...not that they hurt anything...