Blue 'halo' when introducing filler on Aluminium TIG weld

[SpudBoy]

Originally Posted by DSW

It's hard to tell from that pict, but the black on the tungsten and that dull "frosty" section looks a lot like what I often see with alum contaminated tungstens. I'd expect to see the nice shiny area above the black all the way down to the very tip. Alum will wick it's way up a fair ways some times and will keep contaminating the tungsten if it isn't all removed.

That tungsten has had a couple of touch downs, but I have stopped straight away and ground the tip again when that happened. I will try grinding through the tungsten just above the black area and re pointing it. See how that goes. Thanks.

There is a fair old 'crackle' especially at higher frequencies (like 200 or 250Hz) a bit like bacon frying in a hot pan. Not a constant crackle, but random noises & "pops".

[SpudBoy]

Originally Posted by B_C

The only time I get any green or blue glow is when the material wasn't cleaned good enough and your seeing the cleaner whatever you used burning.....That would be my guess

Am cleaning with Acetone on a rag and a green scourer pad.

Admittedly the rag is looking past its best and has quite a bit of black ali stuff on it .....

[SpudBoy]

Originally Posted by Rojodiablo

My thoughts are to drop the pulse for a bit, and try a few things: Freq around 70-90. Tungsten looks ok, so no change. As was stated, EN balance around 70%. Set amps to 40. Use the pedal, and try to start the puddle by starting hot, and back it off. See what it takes to get the start up going well. The welder can tell you peak amps, and last amps used, and maybe ave. amps for that last function. Try to match those parameters with your pulse setup.
If the welder can not give you the amps info, then by starting with a round number as 40, or 100, you can pretty easily approximate what you did that worked- ie 'Started wide open, then dropped to half withing 2 seconds. Well, there is your setup! Peak amps at 40, base amps is 20, and 30 pulses per minute, meaning .5 PPS.
Set the ramp up and ramp down times very low, .25 second. No need to soft start and then no need to downslope a bunch at the end.

Yeah - someone else thought I should get rid of the pulse too. Am finishing work in half an hour, so I can have another go when I get back to my shed.

Ramp up time currently set to 1 second. Ramp down set to 2 seconds.

[SpudBoy]

So, I did the following:
- Cut off my tungsten at the black mark & re-ground to make sure there was no aluminium on the tungsten
- turned the Argon down to 5L/min
- Turned off the Pulse
- Increased the Max amps on the foot pedal from 40 to 50
- held my tungsten closer to the work
- hit it much hotter and much quicker

I am getting less of the blue halo when I introduce the filler, and the tacks are not eating away my 1mm sheet like was happening when I was taking 20 or 30 seconds per tack. These were done is 3 or 4 seconds I reckon.

The nasty crackling and spitting sounds I was getting have gone away.

HUGE improvement, so thank you all very much. Much appreciated. Who'd have thought that more heat would give less melt through.....

Got to work on removing the crater, and then doing a full edge, but the tacking side of things is hugely improved.

This is what I am getting now (tungsten touched on the 2nd to top tack):

[MikeGyver]

Aluminum welding 101: You essentially floor it to develop a puddle as quickly as possible, then back off as necissary and weld.

[shovelon]

All in all, looks like you are on your way.

[B_C]

Don't get too nervous about touching the tungsten when tacking, I sometimes actually
bump the tungsten into the weld joint to get a tack especially if there is a gap, it's no big deal......
I call it GAGING the tungsten, you'll come up with all kinds of tricks before your done......

[VPT]

Originally Posted by B_C

Don't get too nervous about touching the tungsten when tacking, I sometimes actually
bump the tungsten into the weld joint to get a tack especially if there is a gap, it's no big deal......
I call it GAGING the tungsten, you'll come up with all kinds of tricks before your done......

Yup, there have been times that I was in a weird position or holding a couple odd parts together and couldn't hold a filler to bridge the gap. I will try at the tightest part of the joint ot get the two to join and if its not happening I will start to get frustrated and jab the tung into the aluminum to get the two sides of the puddle to join. Then I will go clean my tung and go back to work.