GAS TUNGSTEN ARC WELDING VIDEOSSee the gas tungsten arc welding aluminum "stack of dimes" page here
Old style conventional transformer tig welders weld at 60 hertz because that is the typical frequency of Alternating current in the USA. Ron is using an inverter tig welding machine that allows him to adjust the frequency of the Alternating current. He sets the frequency to 120 hertz and that provides a stiffer and more focused arc. He also mentions setting the A/C balance to 75 which means he is welding with 75% DCEN. Remember that in alternating current you have both electrode positive and electrode negative alternating rapidly and giving you some of the characteristics of each. The Electrode negative provides more penetration and the electrode positive provides what is known as "cleaning action". Without some cleaning action that you get from the electrode positive part of alternating current is is almost impossible to break thru the aluminum oxide and get a clean puddle. A drawback to old tig welding machines is that the electrode gets hot with all that electrode positive going on and you really dont need as much cleaning action as you might think. Thats why inverter tig welders are becoming so popular. When Ron says he as set his A/C balance to 75% , what means is that the are has about 75% Electrode negative instead of 50/50 like you might get with an old school tig welder. Welding at 120 hertz and with 75% Electrode negative lets you weld with a sharpened electrode instead of balling the tungsten electrode. That is a huge benefit. Especially when trying to pinpoint the arc onto an edge or if you need to prevent arcing off on something that is really close to the weld. Some Inverter tig welders like the Miller Dynasty 350 are capable of welding on alternating current with as much as 99% electrode negative and at as much as 400 hertz and are even adjustable as to how much amperage is applied on electrode negative vs. electrode positive (independent amplitude). These type adjustments are not for the typical tig welder building a hot rod but are definitely useful for very precision applications when the heat input must be controlled precisely as in some aerospace precision welding tasks.
Ron appears to be using a miller diamondback #17 style air cooled Tig torch. I dont get that. I would much rather use the smaller and more nimble #9 style torch. Sometimes you have to get the torch in places that the big #17 just wont fit into. Also, its just easier to hold. One consideration though is that the #17 will stand the heat better before needing to switch to a liquid cooled torch. Once you go to liquid cooled, its hard to go back because then you can use the small size tig torch and it never even gets warm...even when welding at high amperage like when you need to weld a cast aluminum transmission case housing.
Notice that Ron is using a piece of copper plate as a surface to weld on. Copper is really useful to have on hand and can be used for a good ground as well as for a heat sink and backing for welds. Its just not practical to use a heat sink on everything but when you are practicing welding on small pieces of aluminum like he does in this video, the aluminum gets saturated with heat quickly and behaves differently than typical weld where the piece is big enough to conduct heat away. If you can get your hands on some copper then great, if not a piece of thicker aluminum is the next best thing to conduct heat out of your practice piece.
Ron demonstrates tig welding by puddling beads without filler metal, then with filler metal, and then he welds a butt joint using 3003 aluminum and 1100 filler metal. 4043 aluminum filler metal is much more commonly used for general fabrication of 3003 and is much stronger than 1100. He uses a 3/32" 2% ceriated tungsten electrode and with the inverter power source he is using, is able to weld with a sharpened point. A note here on tungsten electrodes...Pure Tungsten is Pure crap! dont use it. I dont use it at all. Even on transformer machines like the syncrowave 250. But when using Inverter type tig machines ..definitely do not ever use pure tungsten. Miller Electrics Customer support Department routinely get calls from customers who bought a Dynasty inverter and are having poor arc starts. 9 times out of 10 they are using pure tungsten and simply switching to ceriated or lanthanated fixes it.
There are 2 things to watch for when you are learning to tig weld aluminum and doing the exercises Ron demonstrates...
1. Arc length and
dont use too much of either.
Good luck Tig welding Aluminum.
In this video on gas tungsten arc welding of 4130 tubing, there are about a dozen tips for welding chromoly tubing.
and who calls TIG welding gas tungsten arc welding?
The AWS, and some engineers. Not many welders call it that .. Read The full page of tips for tig welding 4130 tubing