Aluminium tig problems

[72challengerman]

Hey everyone, I have a miller syncrowave 250 and I am trying to weld some aluminium just for practice. I have done quite a bit of ac tig at school (Syncrowave 210) but for some reason My machine isn’t working correctly. I am trying to just lay a bead on a piece of 1/8 plate. I am using 1/8 pure tungsten and a standard collet no gas lens. 100 percent argon at 15cfh. I have my machine set to 150 amps. Ac balance is set to 60 percent, 15 seconds of post flow time, High frequency is set to continuous, yes it is set to ac with the big handle on the front of it, I can’t figure out the issue. I have cleaned my material with a flap disc then with acetone. So what happens is I go to strike an arc and the first thing I notice is that my tungsten doesn’t ball up like it should as this is a transformer machine, then I push my foot down farther and instead of me seeing a nice shiny little puddle I see black soot appearing and then a crater appears and it pokes a hole through my material. I can’t even see the puddle but it is melting my base metal. Tried adding some filler to this mysterious puddle that I can’t really see and it looks like crap. Ill try to attach a photo. Any help appreciated.

[72challengerman]

[G-ManBart]

A couple of things could be happening here but I'm sure it can be fixed. As far as balling the tungsten goes, you want to have it free of contamination and shaped to a blunt point. At that point you switch the machine to DCEP, start an arc and hold it just long enough to get the shape ball you want on the tungsten. Then switch to AC and start welding. Having the AC balance at 60% is too much cleaning for most situations....try 75% and see what happens.

You said the machine is set to AC, but are you 100% certain the leads are connected properly? The left lug on a Sync 250 should be the work clamp and the right lug for the torch lead.

Having the machine set for a max of 150A on 1/8" thick stock you need to be going to full pedal very quickly or the piece will heat up too quickly and then you'll blow holes through it. Hit it hard right away and then back off.

[72challengerman]

Ok thank you. The machine works fine for welding steel. So I don’t think the leads are backwards but will check tomorrow morning. When I try to start an arc it doesn’t stabilise until I floor it and even then it’s all over the place.

[MMW]

Black soot is contamination. If you are sure the material is clean then it could be gas. Do you have gas flowing out of torch? No leaks anywhere? Is torch assembled correctly with seals in good shape. What size tungsten? Using matching collet? Have you tried another tungsten? If you have another type of tungsten such as 2% thoriated (red band) I would try that. Are you holding torch almost vertical? Have you tried a different pc of aluminum? I'm just running through anything I can think of.

[72challengerman]

Gas is flowing out of the torch, the machine was working fine for steel so I don’t think there are any leaks. The torch is assembled correctly and is almost brand new so the seals are good. I am using 1/8 tungsten. I will try some thoriated in a bit here. The collet is the correct size. Torch is vertical and my stick out is about 3/8 of an inch. I’ll try a different piece of aluminium

[G-ManBart]

Gas is flowing out of the torch, the machine was working fine for steel so I don’t think there are any leaks. The torch is assembled correctly and is almost brand new so the seals are good. I am using 1/8 tungsten. I will try some thoriated in a bit here. The collet is the correct size. Torch is vertical and my stick out is about 3/8 of an inch. I’ll try a different piece of aluminium

Thoriated won't work well on aluminum, so I wouldn't bother trying that. One thing to make sure is that you haven't used the tungsten on steel before switching to aluminum...that will cause problems. You have to at least lightly grind the tungsten after steel when switching to aluminum. There is always a bit of transfer between the puddle and the tungsten that causes contamination. That will cause arc wander for sure. Also, 1/8" tungsten is pretty large for 150A or less and that will cause arc instability as well. If you have some 3/32 give that a try. If not, put a finer point on the 1/8" and only ball it a little bit.

3/8" of stick out is quite a bit for a standard cup. What size cup are you using?

[MMW]

G-ManBart - 2% thoriated works excellent on aluminum on a transformer machine such as a syncrowave. I'm sure there is some other color that works too but please don't say "Thoriated won't work well on aluminum" because that just is not true.

To OP - As far as torch goes you have a 1/8 tungsten with a 1/8 collet and collet body correct? That should be fine but you could drop back to 3/32 also. I would try a different tungsten as maybe yours is contaminated? Cup size shouldn't make a big difference for what you are doing, anywhere from #6 on up should work. Could you be overheating it from the start? Maybe set machine to 100 amps and just see what happens. Location? Maybe someone here is local and can stop by.

[Bushytails]

3/32 2% lanthanated is the only thing I use. But, I don't think the selection of tungsten is the cause of the problems.

I'd be tempted to toss my 'scope on the welder and make sure you're actually getting the 40% electrode positive portion of the cycle.

[72challengerman]

Is it possible my machine isn’t switching to ac properly? The handle is super stiff

[G-ManBart]

Is it possible my machine isn’t switching to ac properly? The handle is super stiff

That's not too likely. If you were to open the machine you'd find three sets of fingers that are 90* to one another. When you rotate the handle one set of fingers moves out of contact and another set moves in, but there's a pretty big gap between them. By the time the handle has moved maybe half way between positions the old set of fingers is nowhere near making contact any longer. Those fingers gather dust over time and that along with the shaft being dry in the collar it rotates in will make them hard to turn. I always clean the fingers and wipe them with pure dielectric grease and put a drop of oil on the shaft where it makes contact when I do a service on a Sync 250...makes the handle move much, much easier.

[G-ManBart]

G-ManBart - 2% thoriated works excellent on aluminum on a transformer machine such as a syncrowave. I'm sure there is some other color that works too but please don't say "Thoriated won't work well on aluminum" because that just is not true.

G-ManBart - 2% thoriated works excellent on aluminum on a transformer machine such as a syncrowave. I'm sure there is some other color that works too but please don't say "Thoriated won't work well on aluminum" because that just is not true.

You're entitled to your opinion, but I think 2% thoriated is a poor choice for aluminum. Pretty much every reliable professional source of information on tungsten selection shows 2% thoriated for DC use only with no qualifiers about transformer or inverter.

My primary TIG is a Synrowave 250DX TIGRunner. I've also owned 18 different Synrowave 250 and Synrowave 250DX machines at this point, so I would say I'm very familiar with what works best with them.

Diamond Ground Products tungsten guide is pretty much the gold standard for how to pick the right tungsten for a given application. They don't seem to agree with you either.

Page 11 excerpt:

"Two types of Thoriated tungsten electrodes are available. The EWTh-1 and EWTh-2 electrodes contain 1 percent and 2 percent, respectively, evenly dispersed through their entire lengths. Thoriated tungsten electrodes are superior to pure tungsten electrodes in several respects. The thoria provides about 20 percent higher current-carrying capacity, generally longer life, and greater resistance to contamination of the weld. With these electrodes, arc starting is easier, and the arc is more stable than with pure tungsten or Zirconiated tungsten electrodes. The EWTh-1 and EWTh-2 electrodes were designed for DCEN applications. They maintain a sharpened tip configuration during welding, which is desirable for welding steel. They are not often used with AC because it is difficult to maintain the balled end, which is necessary with AC welding, without splitting the electrode."

[72challengerman]

What’s the best way you guys have found to clean your material before welding?

[ryanjones2150]

Stainless steel wire brush that’s either new or has only been used on aluminum. I write on the handle “aluminum only”, “stainless only”, etc. You’ll know when you get through the oxide, you can see it and you can feel the brush drag. Once you have it brushed good, a clean rag and acetone for a wipe down, and don’t forget to clean the filler rod too.

Arc wandering trouble on low amperage is not uncommon. A balled electrode will always wander on low amperage. A blunt, pointed electrode will give you more stability, but it won’t get rid of it. It’s the nature of AC tig I guess. The lower the amperage, either use a smaller electrode or dress that 1/8” you’re using down to accommodate your current weld.

By the looks of it to me, your test plate is either dirty or it’s not aluminum (or a weldable aluminum at least). If your machine is working AND all other aspects of tig welding are meeting the standard, then the material you’re welding is the only variable left.

Let’s hope your machine is working and you don’t have something wonky in your doofloppy.

[elkvis]

Is it possible my machine isn’t switching to ac properly? The handle is super stiff

This is definitely a possibility. When you light up with the machine set to AC, does the arc buzz? Or does it just have the low hiss of DC? DCEN on aluminum will melt the metal below the oxide layer, and you won't see a puddle, until the metal completely melts away, and you'll get that crater. Arc rectification can happen on AC too. The system as a whole can prevent the current from flowing back in the DCEP direction, resulting in no cleaning.

Also, the black soot is definitely contamination. Get rid of the flap disc. As Ryan above said, just a stainless steel brush. Brush in one direction only, not back and forth. Finer bristles seem to work better for me. After brushing, then use acetone.