wondering arch

Date 12-22-2005 16:16

I have not Tig welded in years but try moving your ground clamp. I have seen it in SMAW before cannot remember what the technical term they have for it is. When stick welding sometimes the arc wants to pull to one plate instead of where you want it to go and moving the ground clamp sometimes helps.

Hey I think I remember.
This is coming from my 2 day long memory. I think if I recall right it is caused by eddy currents. Which I think means the magnetic field is strong in one plate than in the other which causes the arc to pull to oneside. But do not take my word for it my memory is getting shorter and I am just waiting for the day that I forget my way home (not saying that would be a bad thing).

By Lawrence (*****)

Date 12-22-2005 17:50

Arc blow as described above is one possibility.

More info is needed.

Your GTAW Arc will wander if your welding at low amperage and your electrode is too big. The electrode size must be determined by what alloy your electrode is doped with, what alloy your using for parent material, thickness and weather your torch is water or air cooled.

High argon flow rates can make an arc wander.

Poor tip prep (unclean electrode or improper angle) will cause wander.

If your power supply has adjustable frequency on the AC than increase to 150-200 Hz to bring the arc down to the tip.

If you are using pure tungsten (green) with AC and have a pointed tip you will struggle. If yes, switch to Cerium or Lanthanum 1.5%, even thorium is better in my opinion as long as you don't over heat it.

Here are a few General guidelines give or take a gauge #

Alum below 0.063 use 0.040 electrodes

Alum 0.063 use 1/16 dia electrodes

Alum 0.063 to .0.90 use 3/32 dia. electrodes (if water cooled torch you can use 3/32 electrodes up to 1/8)

Try these and let us know how it goes.

By welder5354 (**)

Date 12-22-2005 22:11

Welding Alumium requires a balled end, not a pointed end.
To get a balled end for Alumium welding. Grind and taper the end of the tungsten down to about 2/3 the diameter of the tungsten. Set your amperage to about 150. Hold the the torch directly above a piece of scrap copper (1/4") untill the end of the tungsten balls. This is the preferred way of shaping the tungsten for welding Al. Alumium should be welded by using a continous high-frequency /Alternate Current system with higher amperage than mild steel.

By Lawrence (*****)

Date 12-23-2005 00:16

With all due respect to 5354,

Welding GTAW aluminum does not require a balled electrode.

There is no reason to hold to the outdated notion of balled electrodes unless an old power supply or a poor performing electrode is selected. The lower melting point of Pure (green) electrodes have tradionally forced the balled end. Zirconium (Brown) electrodes may be balled or pointed depending on performance requirements. Thorium, Cerium and Lanthanum doped electrodes won't properly ball.

This topic has been covered in depth in this forum and a search of the words "tungsten electrode" will provide ample backing. Furthermore, any edition of any reputable welding textbook in the last 15 years has good coverage of GTA electrode tip prep for aluminum, not to mention Miller, Lincoln, Hobart, Boieng, General Electric standard practice and training manuals.

Here are a list of conditions that require a balled tungsten:

1, Pure tungsten electrode. (The low melt point makes pointed tip prep impractical.

2, AC power supplies that do not provide square wave output. An old style sine wave will produce too much dwell time on the DC+side of the half cycle to allow for pointed electrodes.

3, An air cooled torch that will not keep an electrode cool enough to keep the point on a given electrode.

4, A desire by the welder to produce a wide shallow penetrating bead profile.

Any power supply that provides AC and Balence control may make use of pointed electrodes when the balence control settings are over about 70% EN.

Try it for yourself and see :)

By Benesesso (*)

Date 12-28-2005 18:28

Lawrence,

"1, Pure tungsten electrode. (The low melt point makes pointed tip prep impractical."

This may be hard to believe, but all tungsten-based GTAW electrodes melt at the same temp. The electron-emitting oxides have higher melting points, but they are not actually *alloyed* with the W. They allow the electrode to operate at lower temps.

"2, AC power supplies that do not provide square wave output. An old style sine wave will produce too much dwell time on the DC+side of the half cycle to allow for pointed electrodes."

Not "dwell time on the DC+ side", but sine waves allow too much time at low voltage compared with square waves.