Ac hf

HEY!
i havent been able to find out this by searching the net so im gonna ask here. when welding in AC squarewave do i need a constant HF curent to go along an keep the arc lit if/if not i would very much apreciate an explenation about why ? im kind of an electronics guy and not the pro welder, so im hoping for a quick answer that i can understand ?
Best regards!

The HF is for starting only. An inverter does not need a constant overlay of HF to sustain the arc.Once the arc starts the HF quits. Its your choice to start HF or lift...When it comes to aluminum, though you had better use the HF to keep contamination of the tungsten down.

thanks! but what does the HF do against contamination on Aluminium?

The HF starts the arc without contact with the metal. It only has to be close so not to transfer molten aluminum to the tip of the redhot tungsten. HF energy causes it to jump the short air gap between the base metal and the tungsten tip.

thanks alot! really apreciate it!
Best regards

Also keep in mind that it is common to have to slightly scratch the tungsten on the material being welded. You do this before you hit the foot pedal or torch button. Just a little scratch, sometimes even just a touch does it.

Actually, Diabolic,
With our units, that is not common, unless there is a spark gap issue, or some malfunction in the HF.

If you are welding with a transformer power source in AC (including some that are marketed as "squarewave") you may need to keep the high frequency on "continuous" to maintain a stable AC arc.

Inverter power sources (such as all Everlast machines) however do not require continuous high frequency when welding in AC mode and generally only need high frequency when starting.

I think the output of a "squarewave transformer" power source is actually not a true squarewave, but more of a truncated sine wave, while an inverter power source's output is much closer to a true square wave. The inverter drives the signal from positive to negative (and back the other direction) more quickly than the transformer can, which helps keep the gas ionized (or in other words the arc "lit") as the electrons flow from one direction to the opposite (current direction changing from electrode positive to electrode negative, or vice versa.)