I've been welding with TIG for a while. The first machine I had was a 250/250 TIG/Stick Lincoln Idealarc. It was a pure sine wave machine with a very large transformer. There was no variation of the arc on AC, just straight 50-50 plus and minus. It was a nice machine but was rather difficult to use on AC for aluminum. I kept it for close to 15 years and then traded it in on a used Miller Syncrowave 200 that only had 8 hours on the meter.
On the Lincoln, I had been using Pure Tungsten for aluminum and 2% Thoriated for DCRP with mild steel and stainless. It worked well enough but, as I said, aluminum was touchy with regard to heat control and penetration. Also, it would cause pure tungsten to form a very large ball after sufficient heat built up. That required stopping to regrind the tip....not a show stopper, but annoying.
On the suggestion of some welder friends, I tried using 2% (red code) thoriated on AC for aluminum as well on the Lincoln. I discovered that it worked quite a bit better as long as you could keep the heat down. With too much heat, the tip would tend to split and cause an irregular arc. This was better than the pure tungsten but still not ideal. It required you to stop and regrind the tip rather frequently.
The Miller, being a square wave machine has some nice features which make aluminum somewhat easier. Unlike the Lincoln, which used continuous high frequency for AC welding, the Miller has high frequency only on startup. It uses the square wave to maintain the arc on AC after startup and that works quite well. I tried both pure and 2% thoriated tungstens on the Miller with similar results, although the welds were beginning to look better. Part of this was due to the square wave, which can vary the penetration to cleaning ratio. Unfortunately, the thoriated was still splitting a bit, although somewhat less than with the Lincoln machine.
With this as a background, I started doing some research on the internet as to the characteristics of other types of tungstens. 2% lanthanated seemed to be a logical choice since it is said to take more heat and avoid the splitting on AC. I saw an ad for a company that offered a free sample and decided to take them up on it. I got a stick of 2% lanthanated and tried it on aluminum with AC.
The results were much better than either pure or 2% thoriated tungsten. On AC, the tip doesn't split and will form a very small ball, which is ideal for maintaining the arc in a proper shape. I decided to order a box of 3/32" in 2% lanthanated. I'll use that for AC on aluminum and reserve the 2% thoriated for steel. The lanthanated will also work nicely on mild and stainless steel. The pure tungsten is now obsolete as far as I can see.
My findings are probably only valid for a transformer machine with square wave. Others may have the newer inverter style machines with greater frequency variation. Such machines will be able to use other types of tungsten to greater advantage. At this point, I'm not ready to spend the kind of money that such machines command. For my hobby work, the Miller suits me well.
Thanks for listening!
On the Lincoln, I had been using Pure Tungsten for aluminum and 2% Thoriated for DCRP with mild steel and stainless. It worked well enough but, as I said, aluminum was touchy with regard to heat control and penetration. Also, it would cause pure tungsten to form a very large ball after sufficient heat built up. That required stopping to regrind the tip....not a show stopper, but annoying.
On the suggestion of some welder friends, I tried using 2% (red code) thoriated on AC for aluminum as well on the Lincoln. I discovered that it worked quite a bit better as long as you could keep the heat down. With too much heat, the tip would tend to split and cause an irregular arc. This was better than the pure tungsten but still not ideal. It required you to stop and regrind the tip rather frequently.
The Miller, being a square wave machine has some nice features which make aluminum somewhat easier. Unlike the Lincoln, which used continuous high frequency for AC welding, the Miller has high frequency only on startup. It uses the square wave to maintain the arc on AC after startup and that works quite well. I tried both pure and 2% thoriated tungstens on the Miller with similar results, although the welds were beginning to look better. Part of this was due to the square wave, which can vary the penetration to cleaning ratio. Unfortunately, the thoriated was still splitting a bit, although somewhat less than with the Lincoln machine.
With this as a background, I started doing some research on the internet as to the characteristics of other types of tungstens. 2% lanthanated seemed to be a logical choice since it is said to take more heat and avoid the splitting on AC. I saw an ad for a company that offered a free sample and decided to take them up on it. I got a stick of 2% lanthanated and tried it on aluminum with AC.
The results were much better than either pure or 2% thoriated tungsten. On AC, the tip doesn't split and will form a very small ball, which is ideal for maintaining the arc in a proper shape. I decided to order a box of 3/32" in 2% lanthanated. I'll use that for AC on aluminum and reserve the 2% thoriated for steel. The lanthanated will also work nicely on mild and stainless steel. The pure tungsten is now obsolete as far as I can see.
My findings are probably only valid for a transformer machine with square wave. Others may have the newer inverter style machines with greater frequency variation. Such machines will be able to use other types of tungsten to greater advantage. At this point, I'm not ready to spend the kind of money that such machines command. For my hobby work, the Miller suits me well.
Thanks for listening!
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