Anybody on here that can tig ally that could come and have a play on my ESAB machine to see whats wrong with it??

I am between hinckley and leicester.

It welds perfectly on DC, but on AC it is useless.

I cannot weld ally without contamination, I tried the other day for a long time with no joy at all.

I was worried that it was "just me" but I am now sure that its not.

The "blasted" zone that you get either side of the weld is barely there when I try to weld, on a piece of material that has other tig welds on it exibiting a good 5mm other side of thr weld bead.

I also suffer with the arc simply moving away from the end of the electrode and coming off the side of it about 5mm up!!!!!

I am sure that there is something amiss with the machine but have no idea what it could be.

its very odd that it is without doubt the best TIG I have used on DC mode!

What type and dia of tungsten electrodes are you using and what is the shielding gas .Could you also tell me the metal thickness and amps you are using.

Cheers Carl

For TIG ==> alloy the electrode needs to be 100% tungsten also the shape of the electrode is not the sharpe pencile one.

more like ball on the end.
the gas should be argon by alloy.

Tks

If you have any photos of the welder it may jog some one.

Just some tips

Argon approx 9 LPM flow

Hf start

Its best with a foot pedal so you can adjust the amps as you weld. If the ally is not pre-heated you will need more amps to start the arc.

Green White or Gray electrodes for AC welding Grind to 120 Deg angle and it will form into a ball as you weld.

Hold torch at approx 80 Deg angle to work piece and fillet rod about 10-20 Deg's

If welding ally sheet you can prep the joint 1st with stainless steel wire this some times helps the arc to start but it must be stainless steel or it will contaminate the weld.

Sorry if you know/have tryed all this but its all worth checking.

Hope its of some help

Jason

quote:

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Originally posted by tks
For TIG ==> alloy the electrode needs to be 100% tungsten also the shape of the electrode is not the sharpe pencile one.

more like ball on the end.
Tks

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I think yours might be the same model as mine Nat ,esab squarewave 200 ? I pulled the cover off it the other day to change it over to 3 phase supply, it looks like the HF circuitry is on one small circuit board, maybe its faulty?, Rest of the stuff inside is fairly basic. might be worth checking all the connections inside first, but watch yourself with the capacitors.
I don't experience any of the problems you describe. I use white tipped tungstens, and i don't grind them, just whack the power up to full to form a ball end. I would think spares are still available from esab. Do you have a manual for yours?

Al.

I had a similar problem until i started scrubbing the filler rod with stainless wire wool first to make sure they arnet adding contamination.

u2u sent
atb Trev

Thanks for the replies folks!

I have done all the obvious and know all the usual ally advice.

Its fixed balance squarewave so no adjustments there.

Yep Wadders its the same as yours, Esab DTA 200 AC-DC Squarewave. I thought and sort of hoped that you would say that, as I am now pretty sure its a machine issue not a Nat issue! With no rod at all, the surface cleaning effect of the arc is only very slight, it sort of pits the surface in a scattered array of pits rather than properly cleaning it.

I always clean the work with scotchbrite and/or a stainless wire brush, then isopropanol,and clean the rod with scotchbrite.

Right!

Trev has been over and had a go with the welder, and confirmed that there is something amiss with the machine!!

Now I have to find out what the hell it is.

The HF start works fine in DC mode and AC mode, but once up and running the HF must not be working properly as the weld does not "self clean" as it should.

Also the arc does not trigger automatic helmets, nether mine nor Trev's switch over when the welder is on AC mode..............

any ideas???

I've read a lot of people saying AC doesn't trigger auto helmets. The HF is only there to initiate the arc, not run all the time. It sounds like it's not switching the balance properly between AC and DC for the cleaning action, the AC breaks down the oxide layer and leaves the white etch mark alongside the weld.

well i would say take of an oscilioscope over there and plug it in.

it will tell you exactly whats wrong with the signal..

(no it won't burn out)

Tks

Right, update!!!!!!!!!!!!!!!

YAY, we have working welder!!!!

Pete, the HF does run all the time on AC mode, but you are right in the cause being the wrong balance when swapping from ac to dc.

Will have to check this one with Wadders, but the front of my machine has clear indications of which is torch and which lead is "earth" clamp on DC mode, but for AC mode it just says "AC" next to both of the terminals...........................

you know where this is going!!!!

I tried swapping the torch and earth connections over. I had assumed this made no odds as on AC both terminals are both polarities!!! However, I had clearly overlooked the obvious fact that as my machine has no balance control, the AC is hardly going to be equal, and therefore requires the leads to be swapped over for AC operation!!

As I said, I could do with confirmation of this from Wadders as my manual makes no mention of it, but it seems to work.

I now have a clearly cleaned zone where the arc is working, and can see a proper pool, and to be honest, when its behaving itself its a doddle to control.

My problem now is that after a few seconds welding, sometimes the arc becomes unstable, and either wanders a lot or flickers and goes out.

I have found that dropping the gas flow helped a lot, and stopping the arc every 30mm of bead, letting the tungsten cool a bit, touching it on the workpiece and then restarting seemed to stop the problem altogether.........could this be the statix buildup issue you mentioned 907 Paul????

Anyway, thanks to Trev, as he did mention that polarity WAS important on AC, but then we didn't try swapping it as it looked right at the time!

I just meant the HF is only needed to start the arc, it doesn't play any further part in the process and the AC cycle is the important part, my inverter cuts HF off till it's needed again. Is the tungsten balling up? Seabass was onto the same train of thought if you look back a bit.

It does not seem logical that the polarity on AC matters.

However it DOES.
The reason being that the AC Ballance can give longer portions of the pulse.. say the Positive pulse could be 40% power, and the Negative pulse 100% power. Hence the heat not going into the workpiece, and being put in the tungsten instead.

I'm no expert (and may have the above info on polarity reversed), however even though its AC, the power is NOT even distributed in each half of the cycle. Some sets have an AC ballance control to be able to adjust this feature.

Hence your problem. and it being cured by swapping the connections between the workpiece and the torch.

I think this explains what is happening.

It does indeed!

Thanks to all for their help, and particularly Trev who took the time to drive up from Northampton to Leicester to come and try the machine to confirm the issue!

thanks all

Nat