tig question

[bulletproof]

i just picked up a syncrowave 250 dx with a water cooled torch. my question is when i am welding aluminum i can't get it to mend. it is hard as hell to get a puddle started and the filler rod balls up and will not fill. what am i doing wrong? any help is appreciated.



did that even make sense?



it welds perfectly when i weld mild steel with it. i changed to continuos hf and changed the polarity. does anyone have any experience with this perticular machine?

[ToyFamily]

I'm self taught but decent on alum so take it for what it's worth...Weld alum AC and steel DC-, DC+ is for balling up the tungstin (sp)..If you try with DC+ it acts like what you are saying. If that stuff isn't the prob. then maybe get the piece more heated before introducing the rod and back of the heat when you bring in the rod. Sometimes I've also seen it when there is not enough angle on the torch so the heat balls up the rod before you get to the puddle. Just my experience. If you are just starting to weld alum try it without rod for a bit to get used to it, then use the rod when you have good heat control. My machine is a lincoln 175. hope any of that helped.

Nick

[Brad]

Didnt mention it but are you cleaning the AL before you weld it? If not that could be a contributing factor

[BumpyDodge]

My experience with aluminum is limited, but the AWS forum has a good thread on it with a machine like yourshere (http://www.aws.org/cgi-bin/mwf/topic_show.pl?id=6548). I used the pure tungsten(green)w/ball technique when I did it on an old Hobart (didn't have an AC balance ctrl like I think your Miller has because it wasn't square wave).

Here are some things that helped me.....
-Clean the aluminum like it's got a bad disease. Use a new clean SS Brush.(I think this is your problem)
-snap the tungsten w/pliers and ball it set DCEP on a scrap piece, then switch back to AC.
-Use a copper backing plate if it's thin
-Preheating with a torch makes life much easier
-the "pedal-to-the-metal, hot and fast" technique leads to cracks - slow down a little on Aluminum, especially if you're used to Tig on steel

Miller (http://www.millerwelds.com/education/tech_articles/articles42.php) and Lincoln both have a ton of how-to info on their sites.

[bulletproof]

thanks guys! well the first problem i need to fix is i need a green ended tungsten. the guy at the welding supply place said i needed red. monday i'm gonna go get one and try that and see what happens. i'll keep ya'll posted.

[mountain4x4]

Pure tungsten works fine, but I've had better luck with ceriated tungsten... You might want to get a couple different electrode types and diameters and see what works best in your machine. I also use a gas lens, which I think helps a lot. I use a gas lens for everything now.

Also, if the filler rod melts before you get it in the puddle, pull the arc back as you dip the rod, then quickly move it forward after you add the filler, so you go back and forth over the weld a little as youre adding the filler rod. If the arc is ahead of the puddle as you add the rod, it'll just melt the rod before you can get it in the puddle.

With Al, you need to set your machine to a higher power level than needed to maintain the weld. Starting the puddle requires a lot of heat, then after it starts melting, you need to back off with the foot pedal quite a bit as you run the bead.

As far as cleaning the Al, it needs to be spotless, then I wipe everything, including the filler rod, with acetone before attempting to weld it.

Just takes a lot of practice, its way different than steel, experiment with different electrodes, machine settings and techniques until you have a nice looking, strong weld.

[bulletproof]

thanks for the tips!

[Urban Wheeler]

My experience with AL is that is has to be really clean, as in wipe it off, wire brush it, and use a torch to heat it and drive out the moisture. That also helps to lift out the dirt and clean it a little. There is such a thing as shitty AL that just won't weld, but that is really dirty stuff.

[mountain4x4]

There is such a thing as shitty AL that just won't weld, but that is really dirty stuff.

True, but I havent run into stuff thats so bad I cant weld it, though I have heard it does exist. Some of the crap you get from the hardware store is difficult in that way, the solution, besides not buying it, is to weld it with the AC balance set more to cleaning, and use more power so you can burn off the crap instead of having it float around too much in the weld puddle. You have to weld it faster than is ideal (in/min stated on the welding chart) and dont have as much controll, but it works. I'm sure the weld quality isnt perfect no matter what you do, but if you need structural welds, you probably arnt using that crap anyway.

[weedwacker]

I welded aerospace parts for ten+ years. If you are welding .100 or less 2% thorted tung works best in general, 100% tung. for thicker material. AL dissapates heat very fast so you need alot of amps to weld it. A straight helium or 50/50 argon helium mix transfers heat much better for AL welding. If you are welding .125 ^AL with a 250 amp machine you will need helium to get decent penetration.

[mountain4x4]

If you are welding .100 or less 2% thorted tung works best in general, 100% tung. for thicker material.

Do you think different machines respond differently to changing electrodes?

I've haven't tried Helium or He mixes before. When you say "transfers heat better" does that mean you get more heat into the Al with the machine on the same power level compared to Argon? Will my Argon regulator work for He or He mixes? Since Helium is so light, do you need to use more of it compared to Argon?

[MC]

I welded aerospace parts for ten+ years. If you are welding .100 or less 2% thorted tung works best in general, 100% tung. for thicker material. AL dissapates heat very fast so you need alot of amps to weld it. A straight helium or 50/50 argon helium mix transfers heat much better for AL welding. If you are welding .125 ^AL with a 250 amp machine you will need helium to get decent penetration.


yes yes yes

[HaWiiLuVeR]

i was told on another board that the electrode requirements were different for inverter vs non-inverter. i cant remember what im using now, but there was an article that said for inverters you dont change electrode types. ac, dc, steel, alum, whatever, its all the electrode.

[Bigger Valves]

I welded aerospace parts for ten+ years. If you are welding .100 or less 2% thorted tung works best in general, 100% tung. for thicker material. AL dissapates heat very fast so you need alot of amps to weld it. A straight helium or 50/50 argon helium mix transfers heat much better for AL welding. If you are welding .125 ^AL with a 250 amp machine you will need helium to get decent penetration.

Weedwacker,
I disagree about the Helium. A 250 amp machine will not need Helium or or other boost in the shielding gas to obtain decent penetration. 250 amps is way more than adequate for 1/8" aluminum. However the Syncrowave 250 is a 310 amp max output machine. 250 amps is its rated output.

Bulletproof,
As for welding aluminum. Yes you need to stick with pure tungsten with your machine. I've played with lanthanated and throiated electrodes with syncrowaves and it only really works well at very low amperages. If you have a high frequency intensity adjustment I like to turn it up a bunch, but that's just me. If your filler is balling up then it's too close to the arc. Keep it away from the arc until it's time to fill because aluminum is very finicky in this area. Don't try to dip until you have some kind of puddle to put it in. When you really start rolling it's effortless and to me it feels almost as if the puddle sucks the filler right in when you go to fill. I like to weld aluminum hot, smooth, and fast. Get a puddle going, fill it in, and don't dilly dally. Find your own rhythm, that's the key. With a butt joint it can be difficult to get them to initially join and fit up is very important.

[Bigger Valves]

i was told on another board that the electrode requirements were different for inverter vs non-inverter. i cant remember what im using now, but there was an article that said for inverters you dont change electrode types. ac, dc, steel, alum, whatever, its all the electrode.


Inverter based machines should use ceriated or lanthanated tungstens in both AC and DC.

Transformer based machines tend to perform best with pure or zirconiated tungstens on AC.

I use lanthanted with DC current on transformer based machines.

I continue to advise everyone to use up or throw away whatever thoriated tungstens they have and never buy anymore. They have no benefits over lanthanted and ceriated tungstens and at the same time create radioactive dust when ground.

[Bigger Valves]

Do you think different machines respond differently to changing electrodes?

I've haven't tried Helium or He mixes before. When you say "transfers heat better" does that mean you get more heat into the Al with the machine on the same power level compared to Argon? Will my Argon regulator work for He or He mixes? Since Helium is so light, do you need to use more of it compared to Argon?


Yes, with helium or helium/argon mixes you get more heat for the same current as compared to 100% argon. This is because helium has a higher thermal conductivity than argon and because it's ionization potential is higher. Basically, the helium because it transfers heat well broadens the arc which heats more metal and allows the center of the puddle to get to a higher temperature and thus penetrate a little further. Also because its ionization potential is higher (more resistance at the arc) helium requires more voltage to maintain the same current. Since heat is a function of both voltage and amperage and is proportional the more voltage at the same amperage creates more heat. Your argon regulator is likely to have a second reading on it for gases other than 100% argon and it might have helium or helium mix. Even if it doesn't helium will not hurt it. Yes higher flow rates are required when using helium. It becomes a double whammy because not only is the helium more expensive, but you use it up faster. All that being said helium is really not typically the answer for the hobby welder. It is used often when welding metals that dissipate heat very well like copper.

[HaWiiLuVeR]

my parents own a party supply store so ive been thinking about grabbing one of their helium tanks to play around with. :)