Hi! I am considering buying a TIG welder with HF start and, since aluminium is something I would also like the ability to weld, it should be AC/DC.
After having studied what is available in my (European) neck of the woods, I have narrowed my search to 2 or three machines, all of the inverter type. Recent machines, because the progresses in those small inverters seem such that the new generation is smaller, more powerful, has more features and is cheaper, so...
Still, even cheaper, it's quite some money and DC only would be quite cheaper. I understand that aluminium can also be welded on DC (electrode positive) with helium. A bottle of helium is less expensive than a welder, but I also read that TIG with helium is so difficult (because the arc gap must be kept constant and very short), that it is only really relevant for robotic welding. So is helium tig usable or not?
Second, the new inverters, being computerised, offer lots of adjustable features. I understand that being able to adjust the ratio between + and - is the minimum, adjusting the frequency is good and adjusting the length of the pulses is also good. One of the machines advertises a "dual wave" process in which it would weld aluminium by switching every half second or so between AC and DC. Is that a gimmick or is that likely to be useful?
Thirdly, I got inconsistent numbers on the thickness of aluminium that can be welded with the same intensity (I got consistent figures for steel). Are the figures the same than steel or do you need double the intensity? Can I weld 3 mm aluminium with, say, 150 A? Or to put it the other way round: what can I weld with, say, 150 A and 200 A? Same question for stainless.