Inverter Based TIG same as Square Wave?

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I've been reading a lot about TIG welding aluminum and have come across many references to "square wave AC," which apparently requires a pointed tungsten vs. a round ball on the tungsten.When looking at welders, however, it seems that some manufactures list "square wave" but some only list "inverter-based."  I understand that there are other advantages to an inverter-based TIG machine, but does this also mean square wave AC?  Or are these features independent?Thanks!-Kerry
Reply:The simple answer is that an AC/DC inverter will have a squarewave.
Reply:Inverter is a type of power supply.  Dynasty, Maxstar, Thermal Arc, PowCon, XMT, Invertec, Passport, etc are all examples of inverter based welding machines.  Transformer/rectifier is another type of power supply.  Syncrowave, Dialarc, Idealarc are examples of transformer/rectifier power supplies.  Square wave is the AC weld output wave form.  Sine wave is another wave form.  You can have choice of multiple wave forms from the same inverter power supply, which the Dynasty's have now.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Not all inverters are AC/DC.  Some are DC only.   Some are AC/DC.  Almost all AC/DC inverters produce at least a square wave in AC.  Some can produce up to 4 different kind of wave forms.  But for many the sine wave form is considered old, but there are uses for it.The oldest AC/DC transformer machines produced a sine wave form for AC welding. The newer ones do usually  produce a standard square wave.The square wave "requiring" a point on the end isn't exactly true.  Balls can be used, but just aswith a sine wave welder, you may experience arc instability.An advantage of an inverter tig welder when it comes to welding is that the AC switching is so fast that HF is only generated at start, and the arc doesn't go "out", at least be observed to.  Another advantage is that the frequency of the AC switching can be infinitely adjusted up to a maximum programmed value, down to a minimum value which can be quite low.   Also the time spent in either positive or negative polarity of the cycle can be skewed to provide almost pure DC neg or DC positive.  Too much positive, and your ball will form, just as in older transformer machines.  Some transformers allow a little skewing of the balance, but not very much, not like more advanced inverter systems.To sum it up, its fair to say that not all inverter based produce AC welding current.  If they do produce AC welding current, it will have at least a squarewave. AC possibly more.  Some people question the need for multiple wave forms since square seems to work fine for most situations, but there are times when an adjustable wave form may be required.  For the most part adjustable wave form isn't something  worth sweating about  unless you KNOW you're going to need it.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT