Strange GTAW Aluminum Problem

I Say strange, but its new to me..
1st off, I'm still 'new' to Al welding, but I welded this telescope
project together without any problems:
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However, I welded that project together with a Miller Syncrowave 350
that I had access to. To save myself the drive, I purchased a Miller
Syncrowave 180SD.
I'm welding the same materials, using the same sized filler, tungsten,
cups, current setup, and shield gas as I did on the 350 machine.
Anyway, here's a few pictures of the problem:
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(262k)
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(152k)
In the first image, I've circled the problem areas. The items labeled
1 & 2 are created (repeatedly) by doing the following:
#1 Strike an arc
#2 Wait till metal looks shiny
#3 Touch filler rod to shiny spot
#4 Instead of joining the 'puddle' the filler rod creates a ball of
metal
#5 Once it does this, the ball just sits there and creates more slag
the longer I try and heat it.
On Item #2 I tried 'Forcing' the ball to go away by fully depressing
the control pedal, with the amp dial set at 125 amps AC. All it did
was make more slag..
On Item #3 I stopped for a moment, then tried to restart the bead.
When I used the Miller 350 machine, I NEVER recall having this
problem. Sure on occasion I'd make a ball at the beginning of a weld,
but adding some more heat always made it join with the base metal.
Now adding more heat just makes more slag. When I first saw this
phenomenon, I thought I forgot to turn the Argon bottle on...
Anyone have any thoughts?
For the record, here's the detail's on the materials and setup.
Base material is 1/8" wall, 2" square tubing from local
hardware store
Filler rod is 3/32" 4043
Tungsten is 3/32", green tipped pure tungsten
Using a #6 gas cup (also Tried a #7 with same results)
Shield gas is 'Pure' Argon, set at 25 CFH
Torch is a 150 amp air cooled unit that came with the machine
Machine is a Miller 180SD set at 125 amps AC on the dial, and
the Clean - Penetrate knob is set at 4 (on a range from 0 - 10, with 0
being more cleaning action, and 10 more penetrating action)
Here's a list of things I've tried:
More Argon flow, Less Argon Flow

Close all doors and windows in the shop, make sure there are
now fans running, nor any drafts.
Fresh Tungsten, Gas Cup, and Collet
Wire brush the crap out of the base metal with a new stainless
steel wire brush cup in a 3/8" drill
Played with the Clean / Penetrate knob in all kinds of
positions.
Take Care,
James Lerch
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(My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent.
Calvin Coolidge
Reply to
James Lerch
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I'm far from an expert on TIG welding, but I have finally made my first decent welds on aluminum (2024) with my Lincoln Square Wave TIG 300 machine. I tried with pure (EWP), Thoriated and Lanthanated tungsten electrodes, before I finally got my hands on some Zirconiated electrodes. The Lanthanated electrodes showed some improvement, but the Zirconiated (.8%) were a tremendous improvement. I'm using gas lenses with 1/16" electrodes on some .090" 2024 scrap to practice on. I found I had to use a lot more shield gas for aluminum than for, say, steel. I could get away with only 5 CFH of Argon on the steel, but the aluminum did bad things until I upped the shield gas flow to 10 CFH. That's with gas lenses. With ordinary collets and cups, I couldn't afford to turn the gas flow high enough to get decent shielding. Just hold your torch up against a bright light and trip the gas flow on, and you can see the vastly reduced turbulence in the shield gas flow with gas lenses.
You have to shield the torch from drafts. When I work on the floor near the welder, I put up a sheet of material to block the draft from the welder's own blower. For small work, I have a home-made paint spray booth with lights in the top, kind of like a laboratory fume hood. It keeps the work area free of any drafts.
The metal needs to be very clean. I use a stainless steel rotary brush, and use it just a minute or two before attempting to weld. Maybe it is a camera artifact, the pictures look like the material is covered with spots. Any aluminum oxide on the surface will stay there, coating the weld puddle, and make it difficult to obtain fusion of the metal. That's why you get that ball of metal.
The machine you have should have a wave balance control, you might have to turn it to more cleaning to deal with the oxides on the workpiece.
I had absolutely HORRIBLE results with EWP (pure Tungsten) electrodes. Maybe the pros can actually make welds with them, I had no luck whatsoever. Try some Zirconiated electrodes, you will be amazed!
My macine and torch came with the Lincoln finger-tip control taped to the torch handle. I had a problem controlling the arc length and using the control at the same time. I finally took the control off the torch, and made up a jury-rigged foot pedal adaptor to take the control. I suddenly had MUCH better control of the arc length without burying the electrode in the workpiece every time I wanted to up the current.
I don't know if any of this is applicable to what you are doing there. I don't really have the technique for applying filler rod yet, especially with the thin materials. If I back up with the torch to apply filler, the weld puddle has solidified by the time I can get the filler to where it had been molten.
Jon
Reply to
Jon Elson
Looks like bad shielding gas.
Make sure your filler metal and base metal are compatible. You can't weld 2024 or 7075 aluminum.
4043 filler is the easiest to use. 5356 is stronger and has more corrosion resistance.
You can try welding 2024, but the welds will crack easily. The only 2000 series aluminum that is weldable is 2219, which needs 2319 filler.
Reply to
Ernie Leimkuhler
Use a stainless wire brush and brush in one direction only! Do not use a rotary brush it just scrubs the contaniments in deeper. Be absolutely certain that the brush has not touched steel before or it won't work. If you grind it make sure the grinder wasn't used on steel. Brush just before you weld. Gas flow should be around 30cfh. PREHEAT. If you put the filler in befor the base metal is hot enough it makes those cool little black balls. Make sure you know what alloys you are trying to weld. Some are difficult at best. The easiest to weld are the 3000 series.
Reply to
Bogone
I dont think you are running enough heat for the tungsten size.
Gunner
"To be civilized is to restrain the ability to commit mayhem. To be incapable of committing mayhem is not the mark of the civilized, merely the domesticated." - Trefor Thomas
Reply to
Gunner

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