Major problems TIG welding aluminium

[Pete F]

Today I had my first go at welding some aluminium, though I can't say what type it was, I was hoping to make up a frame to fit around the door/lid of my sandblasting cabinet so was about 10 mm x 1.4(?) angle from Bunnings.

I'm able to get consistently good to sometimes very good welds (if I can say that, well they look ok to me anyway) in mild steel using a 1.6 mm tungsten sharpened to a fine point, current as required, typically around 60-80 A on 1.2 to 2 mm steel, pure argon with copper coated filler rods (not sure of the brand, something Italian as I recall) obviously on DC.

For the aluminium I tried all sorts of configurations but was basically 200 Hz, same tungsten, various currents, with 1.6 mm Comweld AL5356 filler rods. Basically I could form a puddle (though it's a bugger to see!) and pass it along the material without any real dramas ... well unless I had the current up too high when the material simply caved in on itself Normally though it just seemed to leave a line where it had clearly been melted. The problems were when I tried to add the filler rod. Through my lens the arc around the rod turned a greenish colour and there were sometimes what seemed to be signs of contamination (black soot on the piece after). No matter what I did I couldn't get the filler rod to combine with the parent material. The filler rods melted very easily but simply sat up on top of the piece looking a bit like slag after doing a stick weld.

I have absolutely no idea of what I'm doing wrong and although I know forums don't give you much to go on, hoping the symptoms may suggest something obvious. I'm fairly sure the rods are ok as they're brand new and weren't even opened until today. I tried another, much thicker piece of aluminium (again not sure what type) with similar results. My welder doesn't have many controls, basically just DC/200/2 Hz, downslope control, and current. I tried to butt up a couple of pieces of aluminium and simply weld them together much like you would steel, but no joy there either. One thing I was thinking I should maybe do is change the tungsten for one with a round point instead of sharpened, I'm not sure if that would make much difference?

Any ideas?

Pete

[nutty]

you have said nothing about using ac current are you or is you welder only dc if so you wont be able to weld ally
if you are using ac current then yes the end of your tungsten needs to be balled

[Pete F]

200 Hz AC was being used, as mentioned in my post

Edit: Waitaminute!!!!! I just ASSUMED the other settings were for AC 2 Hz and 200 HZ. Is it possible that this is still DC but being pulsed at 2 or 200 Hz? Sadly the instruction book is to the usual Chinese standards so gives no clue.

[DJ’s Timber]

basically just DC/200/2 Hz

200 Hz AC was being used, as mentioned in my post

Don't think so, you mentioned DC.

If your welder only has DC, you won't be able to weld Aluminium, you require an AC/DC welder

[Pete F]

Ok sorry that was my mistake, bad way or writing it. The settings were DC OR 200 Hz OR 2 Hz, a 3 way switch. BUT I've now edited my post further to wonder if it IS just DC, I'd always just assumed the frequency settings were AC. Man I'll be if this is a DC only welder It's definitely giving symptoms of not cleaning

Could it be pulsed DC? What's that used for? It certainly sounds like a normal AC welder when it's operating at 200 Hz.

Pete

[captain_caveman]

Gday
A model number or brand may help us identify what type of welder you have most units would have a switch marked AC/DC it sounds like you have dc only tig
thanks caveman

[Pete F]

Yeah by the looks of things you guys are quite right, dc only. Well that would explain why I was having such difficulty welding aluminium!!! As mentioned above I just assumed the switch with waveform was AC but not so, pulsed dc. Fat lot of good that is, ha ha. Oh well, I was feeling like I was outgrowing this welder anyway so guess it's time to start saving.

Thanks for getting back to my post so quickly guys, I was going crazy with this. It sounded just fine but looked horrible!

[Pete F]

OT but does anyone have any experience or recommendations regarding this type of welder? 200AMP AC / DC TIG / ARC / INVERTER ALUMINIUM WELDER - eBay Other Welding Equipment, Welding Equipment, Metalworking, Woodworking, Business, Industrial. (end time 28-Oct-09 19:00:11 AEDST) I've seen similar units sold by BOC however these go on ebay for half the BOC price. Notwithstanding the warranty issues I thought it could be worth looking in to. I've been keen to upgrade for a while (and it's now taken on a whole new level of importance, grrr!) but simply can't justify forking out $2.5K but $1000-1200 is certainly doable, particularly if I can sell my old welder.

Pete

[Edster]

It's definitely giving symptoms of not cleaning

Could it be pulsed DC? What's that used for? It certainly sounds like a normal AC welder when it's operating at 200 Hz.

Pete

Pulsed DC is a way to put a lot less heat into the weld while still keeping the puddle going. Good for stainless.

Damn shame you don't have AC.
Perhaps you can tig braze the aluminium in DC.

[Pete F]

Ta, I have some steel welding to do once I restock on steel and will give the pulse function a go. Obviously "thinking" that was AC I never tried that function. One of the reasons for the confusion was because after I bought the unit I really didn't use it for a long time, it's only been now that I'm doing quite a bit of welding I thought I'd try a new material. At least it now makes sense as to why it didn't have the normal AC controls like balance, I figured, ergh it's probably just preset.

Yes it's a shame, especially since I quite like that little welder. It doesn't have a foot control and I badly wanted one as I've found that sometimes the current only needs to be adjusted by a small amount to make a big difference, especially on thin walled tubing. Never mind, looks like I'll get my foot control after all

Ironically one of the things I'm welding now is my welding table, will modifying it anyway. I'll call in to BOC and make sure my shelf spacing will fit my "new" welder

[captain_caveman]

Gday
I've owned one of these welders for a couple of years with no issues
AC/DC TIG WITH PULSE, INVERTER WELDER, PLASMA CUTTER - eBay Other Welding Equipment, Welding Equipment, Metalworking, Woodworking, Business, Industrial. (end time 29-Oct-09 20:00:48 AEDST)
thanks caveman

[Ashore]

Ive also got one but badged under jasic , have also seen the same unit sold as a uni tig , their all the same chineese unit with diffrent badges
Mine works fine , my al skills still need honing , but thanks to the generosity of chips63 who lent me some videos on the subject its getting better

[Pete F]

Ive also got one but badged under jasic , have also seen the same unit sold as a uni tig , their all the same chineese unit with diffrent badges
Mine works fine , my al skills still need honing , but thanks to the generosity of chips63 who lent me some videos on the subject its getting better

Ok cheers for that. I was hoping to do a TAFE course but it's just not going to fit in with work/location so the next best thing is to watch videos, pester Grahame and other guys here with stupid questions, and practice practice practice. Which video did you get and was it worthwhile?

Incidentally I tried the DC pulse today and didn't really like it so back to straight DC for me.

Pete

[19brendan81]

Pete F,

I did a long post comparing all the chinese welders on ebay, its here on the welding forum somewhere. The units all look the same, and most have the same box but in a different colour. However, like PCs, they may look identical but whats inside can be different.

All of the AC/DC ones advertise this clearly, and have 8 or 9 dial controls. The DC only ones have less.

Brendan

[Edster]

The Pulse is somewhat tricky. On the better machines there's a lot of settings to adjust the amount of peak and base current and the durations. Since your machine doesn't have that adjustability, it may be hard to adapt your welding style to the preset pulse modes.