Quote:
Originally Posted by GregWeld
.... Non inverter welders use a balled end (hate that) and green (pure) tungsten works well for this - depending on the amperage being used....
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Greg you are right about hating the idea of a balled tungsten, but this needs some further clarification...
Many old-timers (Like my Dad, who grew up on transformer, ie, non-inverter tig machines before the advent of today's inverter machines) got schooled in the practice of using a pure, balled tungsten electrode when welding Aluminum on A/C. Back then, the only way to have a pure tungsten electrode be able to actually survive the heat of aluminum welding on AC, was to ball the end of it by striking on DC. That made a little "globe" on the end of the electrode, which would help heat to radiate off the electrode tip during Aluminum AC welding, due to all of the added surface area. But, the torch heat zone was HUGE and hard to control.
However, much has been learned in the past 20-30 years, and today we have far superior electrodes which have compositions/metallurgy which can handle the heat of Aluminum welding much better than pure tungsten, and so we can put the desired pencil point on the electrode and have a nice, tight "flame like" heat zone off the electrode.
Today, there is NO reason that you have to, or would want to, use a pure tungsten electrode, and you do certainly not want a balled tungsten,
even if you are using a transformer (non-inverter) machine.
Any transformer machine when A/C welding Aluminum, will perform infinitely better when using a 2% Lanthanated tungsten electrode (gold band) or a 2% Ceriated tungsten electrode (orange, (sometimes looks more like red) band), sharpened to a point with a pencil-like angle. (Be sure to grind the electrode longitudinally) after sharpening the electrode, I grind a tiny "flat" on the very end which is about .030" diameter (using my calibrated eyecrometer). My machine is a 2003-ish Miller syncrowave (big honkin transformer machine).
http://www.thefabricator.com/article...ten-electrodes