Arc extinguishing on aluminium TIG

General · 2 replies · 127 views · 3 followers

Josef K

10 months ago

Hi all, wondering if anyone can help me out with a problem I'm having whilst welding aluminium.
I'm using a made in China TIG machine, just about the cheapest you can get which will also do AC from the brand Vector Welding. When I weld aluminium on AC the arc extinguishes all the time. On DC the arc does not extinguish.
Often it extinguishes almost instantly, before it even stabilises. It also seems to often extinguish whilst adding filler (maybe because I'm moving the torch away to prevent dipping the tungsten, which might be increasing arc length). It also has a really hard time reigniting an arc on any area of the workpiece which already has some frosting from the cleaning action, ie. reigniting on a weld restart.

Has anyone else had a similar experience? As far as I can tell from research, the arc is going out because it's rectifying. I just wonder if there's anything I can do to make it happen less.

Things I have already done:
- checked both leads for good electrical connections
- put ground directly on workpiece
- tried AC on other materials: on steel with aluminium bronze AC 90% EN the arc is stable
- experimented with gas flow, no obvious difference within reasonable range (10 - 16 CFH on #5 cup)
- experimented with frequency and balance, best at 80 Hz and 80% EN. Frequency too high or too low makes things pretty unstable
- tried different tungsten (ceriated, lanthanated, always very cleanly prepped), all seems the same
- tried a #5 gas lense, surprisingly way way less arc extinguishing than with a standard #5
- tried foot pedal and on/off switch

Really appreciate it if anyone has some advice!

Deichwerkstatt

10 months ago

I know these machines really good from my students when they bring them with for the workshops…

Around 80 Hz is good for them, no crazy settings on the balance.

Make shure the HF spark gap is set correct in the machine, set it a little close then what the manufacturer does

Ground directly to the workpiece with a strong ground cable. Place the ground „behind“ the arc

Clean your work like crazy

Put the machine far away and make Shure the leads all run straight with no circles etc

And… use a Alustar Tungsten that helps the most.

And even if you do that these machine will weld sometimes like shit because they can’t hold the settings you give them…

1 Like

Josef K

10 months ago

Thanks Christian! I thought you might have some advice on this topic.
I will check out the HF spark gap. I know the HF is pretty weak because if I forget my ground clamp and try to start the arc I don't get an electric shock. At work I get a shock immediately on my Rehm Invertig if I forget the ground.
On DC sometimes when the arc ignites it swirls around a bit and makes a whistling sound before it stabilises. At first, I thought this was the gas but the noise actually seems to come from the arc itself. Really unusual. Maybe you have an idea why this happens.
I would like to try these Alustar tungstens... but if I'm really honest, if you put a random tungsten in my torch and I welded with it and had to guess what it was, I don't think I'd be able to tell you based on its behaviour. I just don't see such big differences between the ones I've tried so far (turquoise, E3, 2% and 1,5% lanthanated, ceriated). Apart from E3 does have amazing arc starts and heat resistance on AC.
Cheers

1 Like

brian vanderbeek

10 months ago

That whistling sound is the HF arc. When it wanders, the voltage required to jump the arc changes which leads to a changing pitch from the capacitor charging time changing. If the arc extinguishes at longer length it may be due to the wimpy voltage control circuit not having enough authority to meet the demand. A gas lense helping makes sense because of the smoother path through the plasma requiring less than peak voltage to maintain current flow.

I agree with Christian. Check that gap, and do whatever you can to make the wimpy machine's job easier.

I agree with you on the tungsten opinion. I want to try the Alustar but they are real expensive. I'm gonna have to wait till my birthday and treat myself.🥳😂

2 Likes

brian vanderbeek

10 months ago

P.S.
It may not be out of the question that one of the boards in the machine is failing.

2 Likes

Josef K

10 months ago

I hope it's not a failing board because this machine has only been used for a total of about 6 hours weld time...
Thanks for the explanation about the whistling sound. I noticed when the arc start is good and the arc doesn't wander, it also doesn't make noise. Totally correlates with what you say.

2 Likes

Josef K

9 months ago

Hey guys this thread is a bit old and quiet now but I made another interesting discovery. The filler alloy appears to affect the stability of the arc. 5356 works great and looks great too. With 4043 filler the arc destabilises with each dab and frequently goes out. Totally bizarre. Has anyone experienced the same?