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I'm in a TIG welding course, and during the course we (inevitably) messed up a few (suicidal) tungsten heads by grazing/suicide dive into the molten puddle during operation. Standard procedure is to grind down the tungsten using a grinder, but our instructor indicated that grinding the tungsten horizontally (may) interfere with the conductivity properties of the electrons moving through the head. His explanation was something similar to: if the lines formed from grinding are horizontal (by holding the tungsten orthogonal to the grinder) the electrons will have trouble/a harder path to move through, whereas if they are vertical (by vertical grinding) the lines will be going in the same direction as the electron beam. Was my instructor right?

NOTE: In all fairness, he was uncertain as to whether it was true or not, and advised us to test it out personally if we were curious.

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  • $\begingroup$ This doesn't sound right, but without a picture it's hard to be sure of what you are saying. I can tell you that you want a field concentration at the tip - and this means you want some kind of "sharp" shape. It sounds as though one kind of grinding makes the surface more blunt - if so, that would make things a little bit harder. But really, tungsten is a plenty good conductor, and the issue with TIG welding is to get a plasma to form. This is happening outside the head - but that's where the interesting physics happens. Good luck with the course - wear your PPE! $\endgroup$
    – Floris
    Commented Jun 13, 2015 at 1:50
  • $\begingroup$ At the level of physics that you can explore with a welding head it's certainly not "true". Having said that, there are anisotropic transport phenomena in metals, but it takes some serious physical experimentation to even detect them. $\endgroup$
    – CuriousOne
    Commented Jun 13, 2015 at 6:08
  • $\begingroup$ I know nothing about TIG welding, but I found this article describing tip preparation (on page 6), and it confirms what your instructor says. My guess is that the high spots created by grinding act as points where the arc can be initiated, though exactly why this matters I don't know. $\endgroup$
    – John Rennie
    Commented Jun 13, 2015 at 10:00

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