A/C Welding Issue

[Lee Patterson]

Hi Guy's I am new to the forum. I have read plenty off here over the years learning tig welding with my DC welder.
I got a cheap chinese one a few years ago for some odd stainless projects and it has served me well.
I decided to get an upgrade an bought a chinese A/C D/C pulse welder of the same brand. My stainless welding is not amazing but good enough for what I need. I have made some exhaust system parts using 1.5mm stainless tube and was welding at around 80amps on the welder setting. Which maybe be a touch o the high side but seemed to suit be best.
So my new welder arrived the other day and I thought I would give it a whirl today but I am having issues.
I know ally welding is a bit different so I thought I would see what you guy's think before I jump to the conclusion there may be an issue with the welder.
First of all I ran a weld on DC on some stainless tube offcuts 1.5mm thick. I noticed that I at 80amps it was blowing right through the tube in now time and dropping to around 60amps I could get a reasonable weld but was having to move fast.
As I didn't have much time to play I thought I would give the ally a quick go. I have white 1.6mm tungstens and found a bit of plate 4mm thick which I just wanted to run some lines on.
What I have noticed is in basic A/C with 50/50 AC balance at 40amps the tungsten is balling up very quick and large and the arc is completely unstable and all over the place. if I drop down to 40amps I can get a fairly stable arc bit no pooling or penetration and just about the right size balling on the tungsten from what I have read. I turned the welder up to 80 amps and it basic obliterated the tungsten. The end just started balling up like crazy and dropping off like a bit of filler rod! It sounds like the amps are completely out of balance or rising rapidly as you trigger on to me? but maybe I am doing something wrong. I tried changing the AC balance and that didn't help. Just got worse or spattered around more on the job.
I am running argon gas around 8-10lpm

Thoughts please chaps.. Have I done something silly or is something in the welder gone?

Side thought.. once the clean tungsten has balled up when do you need to regrind it and start fresh. Am I correct in thinking you can just cut a square end on a 1.6 tungsten and let it ball?
I tried both options for info. Also gone through about 1/2 a tungsten in 20mins playing! Something is not right!

Cheers
Lee

 

[Wendelspanswick]

1.6mm tungstens on 4mm plate is too small, you really need a 2.4mm tungsten or even bigger. Do you have adjustable balance on your welder? High cleaning results in rapid wear of the tungsten, turn down the cleaning and you end up with a smaller ball on the tip.

Edit, just reread your post and I see you do have AC balance, I think your problem is just the tungsten is too small for the work thickness.

 

[chevy2]

Also, if you have the facility on your machine then try turning up the ac frequency dial quite a bit,
that'll focus the arc better while practising so it does not bounce around so much,

without this option you'll be fixed at 60hz frequency and the arc will tend to dance around more especially on fillet welds.

 

[Lee Patterson]

Thanks for the replies. I don't have adjustable frequency. I have pulse and 2T or 4T options but thought I would start with a basic setup to get weld running and go form there. I hear what you are saying about tungsten size but surely with the amps set low on the machine the tungsten should not be melting away? 80amps and the tungsten does literally melt away all the way up into the nozzle like a bit of mig wire!
From what I have read a 1.6mm tungsten is good for about 60-160 amps or something like that and I am running on or below the bottom end and melting away the tungsten like no tomorrow. I don't want to weld the plate so much as run a bead along the surface of it. That should be possible right?
The frosted cleaning area I am getting is very big too with no pool or anything coming through the middle.
I have cleaned the plate with a brush and scotchbrite but if is was real oxidised could this cause the problem I am seeing or would the right balance solve that? i presume it would not cause the tips to melt?

 

[wheresmejumper]

You want about 160amps with a 2.4 or 3.2 tungsten
set balance at 50, and tweak from there.
80 amps for 1.5 stainless is way high.try 50 to 60

 

[chevy2]

I weld 1.5mm stainless exhaust tube on about 40amps.

 

[wheresmejumper]

Twas just a suggestion.i tend to put less heat into the piece by running hot and moving quick
either way,80 is stretching things

 

[Richard.]

Thanks for the replies. I don't have adjustable frequency. I have pulse and 2T or 4T options but thought I would start with a basic setup to get weld running and go form there. I hear what you are saying about tungsten size but surely with the amps set low on the machine the tungsten should not be melting away? 80amps and the tungsten does literally melt away all the way up into the nozzle like a bit of mig wire!
From what I have read a 1.6mm tungsten is good for about 60-160 amps or something like that and I am running on or below the bottom end and melting away the tungsten like no tomorrow. I don't want to weld the plate so much as run a bead along the surface of it. That should be possible right?
The frosted cleaning area I am getting is very big too with no pool or anything coming through the middle.
I have cleaned the plate with a brush and scotchbrite but if is was real oxidised could this cause the problem I am seeing or would the right balance solve that? i presume it would not cause the tips to melt?

As said above a 1.6 tungsten is too small if your taking it above 100 amps and you won't get a pool going on 4mm thick unless you start off over that. 2.4 tungsten, 120-140amps set the balance 75% DCEN and if you can 100-120Hz . This should get you started then fine tune from there

 

[Richard.]

Can u send a pic of the front of your machine and perhaps one of the guys here can see where you might be going wrong or at least help u set it up correctly. Have you tried putting the balance maximum towards the penetration side dcen to see if that dose stop it balling up. If it doesn't then I guess your balance control dose not work. Put in a 2.4 tungsten and grind it to a point . Set the balance max DCEN at around 120 amps, no filler and strike it. The point should pretty much remain. Then move the balance down 10% towards dcep and try again. Keep doing this and you should see if it's working as the tungsten should ball up a little more every time u adjust it.

 

[Lee Patterson]

Thank you for the reply Guys.. So maybe my old DC unit was running way low on output compared to the dial setting? I would say around 40amps was getting a decent weld on the 1.5 tube. 1.6 red tip on that set-up.
So, I am still a bit confused here. I understand that I won't get a pool going unless I run higher amps and a bigger tungsten on this bit of plate but as yet I am only running on 60 amps and melting the tungsten away? Is that normal? I will fiddle more later if I get a chance and send a pic of the front of the unit.
Moving FWD I plan to weld maybe 2mm ally mostly.. What thickness tungsten is best suited and am I on the right lines with the white tip?

Thank you
Lee

 

[Richard.]

It's not normal no but if your AC balance for some reason is broken and fixed well into the DCEP side of things then 60 amps is enough to kill a 1.6 tungsten try the advice I suggested above to see if the ac balance is working as it should.

 

[Lee Patterson]

Thanks again for the replies.. I will try and check this out tomorrow. I presume I can turn the dial while the trigger is depressed and listen for a change in the sound the arc is making as much as anything else?
As I recall when I last tired it almost seemed as the longer you held the trigger the more the tungsten seemed to heat up.. As in the sound was getting stronger.
Hopefully below is a picture of the front panel for future reference.



Also going back to the DC side of things at 40 amps it was still seeming aggressive on 1.5 wall tube.I thought that the current rating was aprox 30-40amps per mm wall thickness? Maybe that is not correct for stainless?
What should it roughly be for ally? To help me get a ball park if I try a thinner piece of ally?

Can I verify the output amps at the trigger easily does anyone know? I am thinking if I try and earth it through a multimeter it will just fry it due to voltage but I am no electrician!

Thank you
Lee

 

[Wendelspanswick]

'Start A' is your welding current, every thing else you can turn to zero apart from 'Post Flow' which I would set to 5 and 'AC balance' which I would set halfway to start with.
If your tungsten still melts back, regrind it and turn the AC balance one way or the other without changing the amps and see if the tungsten melts better or worse.
The AC balance controls the cleaning, lots of cleaning results in the tungsten receiving more heat and balling up.
The ideal is just enough cleaning so that the tungsten retains it's profile.

Aluminium takes more current than ferrous and stainless.
As a rough guide
1.6mm = 60-80amps = 1.6mm tungsten
3mm=80-100amps=2.4 mm tungsten
This is for a lap weld, a bit higher for a butt weld but I would avoid those for now.
Bear in mind that if you are welding piddly little squares of sheet they will heat up very quickly and the current will need to be reduced, this is where a pedal comes in handy.

 

[Lee Patterson]

Thank you for the info.. Sounds Like I have my current too high on my old machine for stainless for sure! Must be running low power. Explains why DC seemed hot to me!
I will have to get some 2.4 tungsten or try some thinner offcuts with the 1.6 tungsten if I have any. To be fair when I get going I will be mainly butt Jointing. So I need to pick that up! I will try settings as suggested. However I think in this instance the welding amps is marked by 'welding A' start A is apparently for striking the arc when in 4T mode.

Thank you
Lee

 

[Lee Patterson]

Thanks for the info and advice so far guy's I think I have made some progress. I dived out to the garage this evening to try some of the suggested settings. So I still only have a 1.6 Tungsten. But I thought I could set the amps low and strike and arc and move the AC balance dial and see what happens. Sure enough it works fine and I turned up to about 80 amps and tried again and found that on the plate if I went much over 50 the tungsten balls up a lot. Maybe a 3mm diameter ball. at around 80 amps and 60% balance the ball just about holds up. You can see the tungsten is glowing up inside the nozzle and the ball is vibrating slightly but it seems to hold. So I thought I would get some off cut 1.6mm tube and try and run a bit of weld. I experimented from about 40amps and found that even a low balance with lower amps appears to leave quite a large white haze around the weld. The images below show welds getting higher amps and higher balance from left to right and then the last image was at around 60 amps and 55-60% balance. Tip of the tungsten maybe balled to a couple of mm but held nice and stable and I was able to add some filler.





So I was pleased to make so progress.. Now I think I can try fiddling with the 4T mode to try and get the cratering fixed using the downslope.

Not that I will be using it yet but am I correct in thinking pulse is best used for welding close to edges. So does that refer to butt joints?

Thank you
Lee

 

[Richard.]

If your welding close to edges with aluminium in an ideal world you will be better with the variable current control of a foot pedal. You mention pulse in that last post. Dose your machine pulse in AC ? I have only heard of a couple that do because it's not really needed in AC,

 

[Lee Patterson]

Hi Richard,
I will have to try that now you have asked.. Not sure.

 

[Shox Dr]

You need to clean the aluminium better I can still see staining from something on those tubes. Clean clean and clean again, esp if using old, or second hand stock

 

[ukracer]

You need to clean the aluminium better I can still see staining from something on those tubes. Clean clean and clean again, esp if using old, or second hand stock

Are these any good for cleaning ali?? http://www.ebay.co.uk/itm/351093913812 and is it acetone that you need to rub it clear of grease and impurities?? http://www.ebay.co.uk/itm/161098435345

 

[Shox Dr]

yes that would do, Scotchbrite pads are good as well