TIG contamination removal techniques

[jakeru]

OK so on the learning curve of TIG here, I've done a bit of tungsten-weld puddle dipping recently (in both mild steel and aluminum), and I am wondering what is the most effective and economical way to remove the contamination?

On a miller TIG welding troubleshooting guide, it says if the tungsten gets contaminated, to break off 1/2" of the tungsten, and re-sharpen the tip. Is removing that much tungsten really necessary?

Is there anything wrong with grinding off any hard metal deposits and re-sharpening the point, and just scrubbing with a scotchbrite pad any carbon/discoloration deposits on the rest of the tungsten until it is clean? Or would using that technique be detrimental to weld quality. Should I really be snapping off a large amount of tungsten every time I get some contamination?

Oh yeah also, is carbon or other material build-up inside or on the front edge of the ceramic cup a problem? Can those cup deposts be safely ignored without impacting weld quality, or is it important to keep the cup surfaces clean as well. (If so, how do you clean the cup, in particular the inside of it.)

I am trying to reduce the arc wander I am getting recently, and I think contamination may be contributing, and maybe how I sharpened my tip. I remember when doing some welding before, that holding the tungsten very close to the work would cause all the heat to concentrate right next to the tungsten. But with contamination, it seems that doesn't even work, the arc wanders all over. I'm wondering what techniques you who are very proficient at TIG welding are doing it. (Aside from not dipping the tungsten in the puddle in the first place.) Thanks!

[performance]

Jakeru,

The breaking off the piece of tungsten is the standard way to decontaminate a tungsten. Now with that said, it depends on how critical of a job you have. The reason you break the tungsten off is so that you don't contaminate your tungsten grinding wheel when removing the deposits. The grinding wheel should be dedicated to the task of grinding tungsten only. "Sharing" the wheel for other grinding applications is usually forbidden as it contaminates the tungsten while grinding with whatever was ground on the stones before.

A certain amount of build up inside the cup can be experienced from time to time. Usually the build up can be removed quite easily with the fingers by scraping the inside with your fingers or a small pick or tool very gently. A lot of times the build up is from poor operating technique.

A wandering arc is usually a sign of tungsten contamination, particularly in Aluminum AC operation. You can also adjust your frequency higher on AC to stabilize the arc. IF it is wandering in DC, then readjust the location of your work clamp.

[jakeru]

Thanks a lot Mark, the contamination of the grinding wheel reason makes sense enough to me not to do it!

It's amazing how sensitive these tungstens are to contamination (if all it takes is a dirty grinding wheel), but given the extra arc wander I am seeing compared to what I remember in the past, I can believe it.

Kind of reminds me of a stainless steel project I wire brushed with a carbon steel wire brush, that ended up "rusting" in spots where I wire brushed, from apparently the minute metal transfer of the wire brush material into the stainless steel.

And indeed, on the inside of my cup just look like a light layer of carbon deposits. (Maybe from forgetting to turn on the gas once or twice. )

[jtybt]

Good post! I was wondering about cup contamination and what was acceptable and what was necessary to clean it with.

[performance]

Whenever, you begin to loose the proper gas shielding cone, you will need to clean the cup, especially before it comes loose from the heat and falls into the weld puddle.