I attempted tigging aluminum for the first time today and had a couple issues. I was using a Arco Heliwelder with water cooled torch.
2% thoriated 3/32" tungsten on AC welding
Not sure what filler rod I was using but I can check tomorrow when I go back to practice more. It was close to 3/32 if not 1/8".

There are two problems. My weld beads aren't very tall and my weld bead is very wide spread even though i'm using 2% thoriated ground to a point with a small flat on the tip.



The second problem is that my welds are cracking at the beginning of the weld. You can see where this weld cracked right in the middle. I don't know why this is happening. I would expect a weld to crack at the end if I had a crater at the finish but this is the very beginning.

[IMG][/IMG]

So how do I make my bead more narrow and taller. I assume I need to get my arc closer to the plate even though it's pretty close already. Smaller tungsten might help. I also think I need to use more filler though with the large 3/32" or w/e filler I was using I felt I was dipping pretty often.


Modified by cjernigan at 11:04 PM 4/30/2008

 

How thick is the material were you welding? The first photo din't load for me, but the second looks like you were using too much heat, and moving too slowly. The cracking may be a result of overheating the base material.

 

Too hot.

Turn the heat down like 15-20 amps and then work on speed.

Once the material starts to heat up, you have to back off the pedal or it will begin to "sink" into the material, you will eventually blow into it.

Its like driving a car, to get up to speed you have to sit on it for a second then you will taper off a little bit to maintain speed, otherwise you will continue to speed up and speed up and melt it.

 

Less heat!

 

pulse the pedal with the same heat and see what happens.

 

I'll research pulsing. I watched a youtube video and saw the correlation between pulsing the pedal and dipping. I always thought that was similar to spot welding thus it wasn't a good method of welding. I'll let you know how it goes.

 

to help the heat you can switch to a larger filld rod size, it will help cool the puddle and not give you such a wide bead.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Shadytrixta1 &raquo;</TD></TR><TR><TD CLASS="quote">pulse the pedal with the same heat and see what happens.</TD></TR></TABLE>

Learn how to do it without pulsing first.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by k24em2 &raquo;</TD></TR><TR><TD CLASS="quote">

Learn how to do it without pulsing first.</TD></TR></TABLE>

Agreed. The appearance of the bead should come from your torch/filler rythym, not pumping the pedal.

 

K, I'll do what I can to get it right without pulse then. Wish I had more lab time to really hammer out some serious practice.

 

Is this an inverter machine that you're using? I've heard if the frequencies are all out of wack this could occur.

Definitely looks like too much heat either way. What was the amperage and what was the base metal thickness again?

 

It was .065" sheet and it is an old inverter machine. The machine is good I know quite a few people that use the machines frequently for aluminum and are fine.
I plan to use pure tungsten this next time and lower my amperage so that I max out around 75 if I depress the pedal fully so that i'll be running around 65 at 3/4 pedal. I'll try putting in less heat. Like i said this was my first time doing any of this.

 

Don't use pure tungsten with inverters. Thoriated works fine for AC and DC. Some prefer ceriated or lanthanated though.

 

Go with 1/16" tungsten, and 1/16" or 3/32" filler, depending on how wide/tall you want to make the beads. You'll probably be around 1/4" width or less in bead width then.

 

Zirconiated tungsten is best for aluminum. Pure alumium can't take nearly as much heat but it doesn't spit nearly as easy, pure is only used on the old school transformer machines.

 

just looked at the weld the crack is prob from when i finished the weld is there a crater at the end of the weld? it tends to crack the bead

 

If you have a thin piece of metal the heat transfers very rapidly. It seems like it's really thin because of the crater at the end of both beads.