Tungsten Size -vs- Penetration

[malich]

I have been working on TIG welding 1/4" MS and 1/4" Aluminum both with 3/32 Tung and 1/8" Tung.

If welding with the same amps and a large tungsten, would you get more penetration into the medal? It appeared that way to me, but maybe it was jut my imagination.

Thanks!

[Mark...]

no more penetration. Just use the bigger tungs for higher amps and visa versa.

[David R]

Mark said it.

The only reason I use the "Oversize" tungsten is I can see it better.

David

[malich]

I was kind of thinking the same thing. I asked because It seems like I get a nicer weld using the 1/8" instead of the 3/32" Tung. It seems like the puddle stats a little easier...

Thanks!

[Supe]

If anything you'll get slightly less penetration, as a smaller tungsten can typically focus to the arc more precisely, albeit very slightly.

[malich]

Hey Supe,

What's the difference if I grind both tungstens to the same point? How would the arc focus differently?

Thanks,
Mike

[David R]

I am not supe..... But..... the more pointed the tungsten, the more focused the arc. A blunt tip will have a wider arc.

If you grind them the same, then the arc should be the same. Maybe a little wider for the bigger tungsten. The tungsten works best when its HOT. SO a little amps on a big tungsten will not let it get hot and will not work as well.

Help?

David

[pulser]

It's common knowledge that a sharp tungsten gives a more focused arc, right?
Sorry, guys but there is evidence to the contrary.

Here it is: http://www.weldingweb.com/showthread...lectrode+angle

See how the arc comes off the sides of the electrode tip? So, the blunt electrode actually gives a more concentrated arc.

Now, it is true that a smaller tungsten/sharper tungsten, may work better for getting in very close the root of a tight joint or the corner of a "T" joint, and a tighter arc gap does give a more concentrated arc. Also, as mentioned by others, a smaller tungsten/sharper tungsten improves arc starting and arc stability and is needed for as lower amperage is used.

[David R]

DAYMIT pulser, now I gotta try it!

Lemme consult the bible.

Thanks

David

[pulser]

Originally Posted by David R

DAYMIT pulser, now I gotta try it!
Lemme consult the bible.
Thanks
David

I was thinking you might say that! It will be interesting to hear if you can see any difference with the tip angle. Go for it.

[David R]

OK, today I gave it a shot. I used 1/8" tungsten. Ground one to a short blunt point and one to a LONG skinny point. No flat was included.

For the test, I used a piece of 1/8" plate with the mill scale ground off. I really didn't know how to make it a good test, so I set the tig welder on pulse, 125/5 amps. 60% high current, 40% background .5 Hz. I got the arc started, moved the tungsten to a fresh spot on the plate and hit the pedal full. After 3 welding pulses, I let off the pedal. I did this with sharp and blunt tungsten. I came to the conclusion I can't see the difference. Here is the pic, top 2 dots are sharp long point, bottom 2 are blunt point.


The dots in the center are pretty much the same, but the camera angle makes them look different.

I took a set of vernier calipers and measured the heat affected zone and the disturbed metal in the center (puddle). Not enough for me to see, so for me its just sharpen the thing and dip it in the puddle.


OOps, here is the back side B is for blunt. Still pointed, but a really short point.





David

[pulser]

So, no difference in this test, from what you could see?\
Well, that's welding for you.

[David R]

I learn from this stuff I do. Apparently its nuttin to get fired up about.

I also turned one around and used the flat tip. The arc went off one corner of the electrode until it got really hot. Then it seemed to come off the whole electrode, but didn't make much of a puddle, so I am sure you need a point, but the angle is "pointless" to me.

David

[malich]

Good idea for a test David!

The only thing I can add is I have noticed a difference when trying to form a puddle on a MS fillet weld with the sharp point is seems to be more focused and the puddle does start easier.

That's the only place I have ever noticed a difference so when I weld fillets I make a nice sharp point on the tungsten.