Tig welding tips, questions, equipment, applications, instructions, techniques, tig welding machines, troubleshooting tig welding process
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dhoop
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    Sun Jan 17, 2010 12:23 am

I am an apprentice and have a question that my instructor told me to find the answer to.
Why does Tungsten melt when welding on reverse polarity?
g234me
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    Sun Jan 17, 2010 6:56 am
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    Newnan,GA

I just started TIG school last Monday myself. One of my instructors happens to be the Admin of this site. He also instructed me in MIG last year.
The tungsten melts in DCEP because current flows from -to+ so the current is going from part to be welded to tungsten. Which heats it up.
In DCEN current goes from tungsten to part, heating up part.
In AC current goes back and forth which gives cleaning action on aluminum. Most TIG machines have a setting for more cleaning or deeper penetration. Hope this helps.

Martin
brian
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    Sat Oct 03, 2009 10:11 pm

You said it Martin, on DCEP about 70% of the heat will be directed toward the tungsten, the opposite on DCEN.
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