Possibly daft new TIG welder question

When TIG welding aluminium alloy, on a Migatronic 220 AC / DC TIG machine, i know that i should be using a tungsten that has balled. However, if i
take a new ceriated tungsten from the box, sharpen it, flatten the tip to say small "flat", can I then immediately start alloy welding with it, or should I ball it first, maybe on some scrap alloy?
Secondly, I have welded some -10 weld on Aeroquip pipe fittings to an alloy cam cover on a race engine. The weld on fittings are about a 1/4 inch thick on the boss for welding, and the covers a similar thickness. I ended running about 100 amps, and my 3/32 tungsten has started to erode. Is that too much current / too thick a material weld for that size tungsten?
Thanks.
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Best Regards,
Chris.
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typitcal practice is to ball the tungsten on copper, using reverse polarity. Careful as you won't need much amperage. However I have also done it your way, the tungsten will form to a ball as you use it. I prefer to use Zirconium tungsten for Al.

100 amps is not too much for 3/32" tungsten, check your post flow time to ensure gas coverage until the tungsten cools. Use gas lens for best gas coverage.
Richard
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If your Migatronic is an inverter machine it will work just fine with tungsten prepared just as you have described. If tungsten seems 2 small to take the amps you are using, just try the next size up.
k
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This is how I understood it too: inverter machines apparently don't need to have 'balled' tungstens. Simply grinding a point and flattening would be enough.
Though my tungstend often end up with a ball, sooner or later.
But I'm just teaching myself to weld too :)
Apparently, older (transformer) welding machines are more critical in respect to the use of balled tungstens. Don't ask me why.
Peter.
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If the inverter has an adjustment for arc balance for AC welding, then you can not only adjust the balance in favor of electrode negative, but also adjust (the amperage) both the positive and negative sides of the AC wave. An example. electrode + 50 amps electrode - 150 amps AC balance 68%
Richard

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When I weld on AN fittings, I consider the stuff I'm welding to - if it's .059 AL sheet, then I might use a lower current. 100 amps sounds right for what you're doing, and yes the electode does tend to get used up a bit. I personally have started to use a slightly tapered point for Al welding, it seems to give me better arc control that just putting a ball on the end of an unground electrode. But I tend to do lighter material than a cast valve cover, typically.
Brian

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alluminum         Current type AC    butt 280Amp        electrode 3,2 - 4mm alluminum         Current type AC    lap 220Amp        electrode 4mm alluminum        Current type AC    fillet 300Amp        electrode 4 - 4,7mm obviously at 60Hz of AC welding current.
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