Balled VS Tapered tungsten electrode

[waqasmalik]

Hi all, My question is regarding the use of balled electrode vs tapered electrode in AC Welding of aluminium. I have studied some books which says that balled tungsten electrode produces intense heat source as compared to tapered tungsten electrode. But, recently i have studied some literature of Miller electric which says that tapered electrode produces more focused and high heating arc while balled electrode produces wandering arc.

I would like to know the opinions of experts in this regard.

Thanx in advance

 

[racookpe1978]

Can't talk about Al welding practices.

For what its worth, we only accept tapered tungsten tips for steel and stainless welding in the plants.

 

[waqasmalik]

Thanx sir, but what is the reason behind this convention?

 

[Tmoose]

http://www.thefabricator.com/article/aluminumwelding/5-tips-for-successful-aluminum-gtaw

tip #10 here from a very practical fellow - has some "why"

http://www.weldingtipsandtricks.com/welding-aluminum.html

 

[waqasmalik]

Ok, We don,t make a ball, we make it round. But why round for aluminum, tapered for steels?

 

[kingnero]

AC vs. DV current. Google must have some information about this.

 

[kingnero]

That must've been AC vs. DC current...

 

[EdStainless]

Points only work with DC, when you reverse the polarity they don't function correctly (no stable arc).
So for AC welding you use rounded or balled electrodes.

We weld SS and Ni alloys. The electrodes are ground to a taper (actually polished, no grinding marks allowed) and then a flat is put on the tip (a sharp point will not last).

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P.E. Metallurgy, Plymouth Tube

 

[Tmoose]

Miller, the maker of those blue welding machines, says this about using ceriated tungsten-
"When welding aluminum, it has become very acceptable to grind a point on ceriated tungsten (especially when welding on thinner materials)."

And this
"Pure tungsten melts at a lower temperature causing it to easily form a rounded ball at the tip. When the ball grows too large, it interferes with your ability to see the weld puddle and causes the arc to become unstable.

http://www.millerwelds.com/resources/tech_tips/TIG_tips/hints_tips.html

 

[waqasmalik]

Tmoose

Exactly,you pointed out all right