Is AC required for aluminum welding?

[tomsign]

can all ways count on you Stan
Thank You Sir

[SICFabrications]

now, to the OP and the original question of can dc weld aluminum tig....... yes, it can, you had better have the parent metal "more than surgical" clean, you will be using helium instead of argon or helium/ argon mix. as said before, this is NOT a process for the beginner and sometimes it isnt for the experienced either.

there is a reason why the tig machines have adapted to AC.

gadget said it well, the ac is constanly switching between straight (electrode negative) and reverse (electrode positive) polarity. on the old transformer based machines, they made this switch 60 times per second (hertz) when the straight polarity is on, the arc is heating the metal, when the arc switches over to reverse, it "blasts" the oxides off the parent metal. the drawback is when the machine is in reverse, it actually super heats the tungsten creating the "balled" end on the tungsten.

the invent of the inverter machines, you can actually set the hertz of the switching of polarities and also set the balance (setting of neutral in the sine and cosine of the ac current waves) higher the balance, the more cleaning action, but, youre gonna spew tungsten into the weld because you are making the reverse polarity more dominant and over heat the tungsten...

hopefully i cleared some stuff up for ya

stan

[rustycase]

Good explanation, Stan!
rc