Tig weld aluminum

Date 02-06-2010 06:52 Edited 02-06-2010 07:39

Hello Chevy_welder, the majority of aluminum welding done with the GTAW process is indeed done with AC current, it also requires a hi-frequency generator to provide arc continuity and argon, helium, or an argon/helium gas mix, there is also some that is done using DC straight polarity and helium shielding gas. GTAW aluminum welding done on the cheap, requires a hi-frequency generator and an AC stick welding machine or one that is capable of producing AC current. A true GTAW aluminum capable welding machine usually has the capability to remotely vary the amperage output of the machine and also control the shielding gas via a synched solenoid and also generally has the capability to control the afterflow time of the shielding gas(this avoids burning up the tungsten). That's the short rundown, recent technological advances have expanded the capabilities of machines designed to GTAW weld aluminum and any other weldable material, an explanation of all of the different variables out there would take a whole lot of time and certainly be outside of my knowledge, yet collectively, it is likely that others on the forum could give a very complete rundown. Hope this explains a bit of what you were asking in your question. Best regards, Allan

By Superflux (****)

Date 02-06-2010 07:47

Chevy,
Yes it is possible to weld Aluminum (I have welded pivot sprinkler irrigation pipe) with straight polarity and pure argon. Not the most desirable set up but the basics can be performed this way even with out Hi Freq and remote amperage controls.

By Tommyjoking (****)

Date 02-06-2010 20:55

Manual Tig welding is typically applied using a powersource/machine that is constant current or CC. The majority of stick welders can be used as tig welders as well, whether AC only, DC only or AC/DC most of these machines will be CC. The flip side is a CV power source this is typically used for wire or Mig welding. There are not a ton of machines that are capable of both CC/CV but they are out there and usually rate a higher cost because of that flexability. For 98% of any aluminum TIG welding you will do whether at home or on the job, you will be using an "AC" or AC/DC capable machine with a high frequency arc stabilizer. Most "stick" or arc welders will require the addition of a high frequency unit to be able to pull this off. However there are plenty of ARC/TIG machines with it built in, miller synchrowaves, Lincoln squarwave tigs and Esab heliarcs are both popular and economical machines with this capability. I have used a simple "tombstone" or buzz box Lincoln 225-250 stick (read cheap not bad just inexpensive..they sell them at home depot) welder with a high frequency unit added to weld up aluminum boats day in and day out and it worked great. So you do not necessarily have to have a 5k machine to do this...they are just nicer and have more capability.

By Blaster (***)

Date 02-06-2010 20:56

An AC balance control, while not technically essential, sure makes aluminum work a lot more pleasant. A balanced wave results in a lot of unnecessary heat being directed to the electrode. This limits limits the maximum current levels possible for a given electrode (limiting thick aluminum performance), and also results in a wider arc and bead (limiting thin aluminum performance).

Purpose built AC/DC square wave TIG machines are really the best way to go if you can find access to one.

By chris2698 (****)

Date 02-07-2010 00:44

go over to the Hobart forum and you can ask guys there and there alot of people who prefer to weld aluminum useing dc and helium. I was really amazed of how well it welds. I seen a bottle of helium at school the other day and am dieing to try this process out to see for myself how it welds

By Iron Head 49 (***)

Date 02-07-2010 10:22

I’ve only played with 100 % helium a few times. You can pretty much cut your heat in half. One thing I do remember there is a very small window that you can get an arc started, compared to 100% argon, but once that arc starts you better take off! LOL!

By chris2698 (****)

Date 02-07-2010 18:25

not bad and it looks like the plate has to be cleaned extremely well. We use this trimix gas at work I think it is argon carbon dioxide and helium mixed and yes I can tell the helium really does help to punch deep into the metal

By Blaster (***)

Date 02-07-2010 20:18

The trimix is for stainless MIG. Argon & helium blend we keep around for aluminum GMAW and TIG.

By chris2698 (****)

Date 02-08-2010 07:50

we're useing trimix on armored plated steel

By Blaster (***)

Date 02-08-2010 17:37

Woops, sorry Chris. I thought you were a different Chris on this forum, from where I work.

By Metarinka (****)

Date 02-10-2010 21:23

we use 100% helium for all our semi-auto GTAW orbital welders.

arc initiation is harder, the torch has a very low standoff distance (few thousdandths) to start the arc then it's lift to normal working height. something possible with a CV head on an orbital controller.
it doesn't cut our heat in half but increases the pentatration for a given bead width by a good portion.