Convert to higher frequency in order to weld aluminum

[salright]

Hello all-
I acquired an older 220v AC DC welder which I was able to retrofit with a TIG attachment. It works wonderfully welding steel. I was interested in welding aluminum with it as well, however from what I've read it helps to have a higher frequency as well as having a square-ish wave. Is it feasible to make my own frequency converter to go from the standard 60 Hz to around 100 or 120 Hz? They say it helps to have a square wave, triangular or a soft square wave as well. We are talking about lower voltages, but higher amperages, like in the 100 to 150 Amp range. Any ideas or suggestions to help me out are much appreciated!

 

[dick_freebird]

If you look on eBay you may be able to find a used HF attachment
for less than the cost to make.

Square waveforms reduce the "time away from peak" and can
eliminate the need for a HF starter. A sine wave has enough
"valley time" for an arc to snuff. Triangular is worse than sine.

The HF is not just 120Hz, it's going to pulse many times per
cycle so that the arc can't die out.

Steel can be welded DC. The AC waveform is used on aluminum
because one direction has favorable metal transfer, and the other
favors disrupting the native oxide (but has inferior transfer and
heats the electrode instead).

 

[salright]

Thanks for the suggestion and info. There were just a few on ebay and it seems the lowest runs around $1k. So from the sounds of it maybe I don't need the HF? Do you think it would possible to just make a converter for a square wave then or am I looking at some pretty expensive parts for building something like that?

 

[FvM]

Welding transformers are special designed devices involving a high leakage inductance for current limit. They can't perform well at a higher frequency and won't reproduce a rectangular current waveform, I fear.