[hotshoe]

Need some advice on what happened here. I was trying to cap a 2.75 dia aluminum x .10 wall cylinder with .100 thick end plates. Here is the set up and subsequent problems.
1. Not sure of the aluminum alloys, but assume they are a weldable alloy.
2. Not aware of any clear anodizing on either parts.
3. Prep included sanding, brushing with stainless brush and acetone clean.
4. Welder is Miller Synchrowave 180 on AC. I tried various amp settings from 50 to 150 with the same result. Checked grounding and it was good
5. Tried both .062 and .093 tungsten with same result. Tungsten was "Pure".
6. At arc strike I got what could best be described as arc scatter then it started to puddle with what appeared to be black impurities in the puddle. The two component did not flow together. There was also a lot of smoke and soot around the weld.
7. The current selector switch does not have the nice click when moving from DC to AC. Welder works just fine on steel and DC.
8. I am somewhat suspicious of the welder on AC being part of the problem, however in the past I have not had any problems welding aluminum.
9. Even after grinding out the original weld and cleaning the mating surfaces, these conditions were still in existence.

I tried to attach some photos to this message, but I guess I am not smart enough to do that or maybe my computer doesn't understand my commands. If you want some pics let me know at castman495@yahoo.com or guide this dummy through the cut and paste process.

Any ideas and recommendations would be appreciated.

Chuck

[AndersK]

Hi and welcome

I assume you have checked gas flow.

Can you hear the noise from AC frequency or see any frost band around the puddle?

I'm with you thinking it might not have switched to AC mode.

If you look in the video section of the forum Jody has one welding aluminum on DC that might help trouble shoot.

[exnailpounder]

Hotshoe. Welcome. I don't know about the 180 but I had a 200 and I had a hard time welding alum with pure tungsten, balled up too much and the arc wandered all over the place. I used thoriated and it worked way better. It could be a balance problem but you didn't include your settings and equipment. Gas lens, flow rate, balance setting, torch size...etc. Pure tungsten will work, a blend will work better...let us know

[hotshoe]

Thanks for your replies, your help is appreciated

Here is what I have:
Gas flow - 15 cfm
#8 Gas lens & cup on a 17 air cooled torch
According to the Miller owners manual the balance is 60%EN, and 40%EP
The Miller manual recommends checking to see if the High Freq is continuous and the proper setting. Unfortunately the manual does not cover this operation.
In the past when I have (somewhat successfully) welded aluminum, the weld looked like it was applied with a putty knife and had a dull gray appearance, not the shiny stack of dimes look.
I will try some 2% later today.

Thanks again

Hotshoe

[hotshoe]

Think we nailed the problem. After checking the manual and call to Miller I was able to get inside and lightly sand and set the point gap to .010. Miller said this needed to be done every three months, at least according to the manual. I then re-loaded the 3/32 pure tungsten and #8 gas lens, 150 max amps and set the flow to 20 cfm. I then noticed that there was a very slight breeze blowing across the workbench so I closed the back door, something that could have been there yesterday and I didn't notice. Bingo, what ever fix was the issue it seemed to work as I was able to get a decent pass with this current setup. Thanks for your help and getting me pointed in the right direction with the HF issue. I am pretty sure it was a combination of things that got me in the ball park.

Thanks for your help on this

Hotshoe