New to this excellent forum, and to welding aluminium alloy, and quite new to TIG in general. my machine is an elderly Migatronic MTE220 transformer based, single phase, and as its name suggests, it's a 220 Amp one. I have been fairly successful, in an amateurish way, at welding mild and stainless steels, but not so with aluminium. I have practised laying a bead on 1/8 inch thick flat sheet, but more often than not end up with a flattish ribbon nearly a half inch wide. I am using an air cooled small torch, with a 1.2 mm grey tungsten. Filler rod is only about 1/16 inch diameter, and I feel it's not depositing enough filler material. Should I be thicker on the filler rod? The machine came with a slightly bigger torch that will take collets for 2.4 mm tungsten. maybe I need to use that?
I am also wondering if my number 5 cup is too small, as at the end of my bead attempts, even with slope down utilized, I get a small pit or crater. It's almost as if the gas is too powerfully concentrated and is making a crater by the force of the gas itself.
I look forward to the videos, they have already helped a great deal, thanks for producing such excellent tutorage.
- Otto Nobedder
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Weldmonger
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Posts:
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Joined:Thu Jan 06, 2011 11:40 pm
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Location:Near New Orleans
Hi, Chris,
Yes, 1/16 filler will work you to death trying to build a bead with aluminum. It looks like you're putting down a decent amount because aluminum expands with temperature, but then shrinks a lot when it cools (this, too, is the reason for the crater at the end, you need an extra dip or two as you tail off to compensate). A 3/32 filler rod will make a difference for you, and except for fine work on quite thin stuff, I use 1/8" filler almost exclusively for aluminum.
As for the 1/2" wide bead while not building height, does your machine have an "arc balance" control? You can narrow the bead a bit by adjusting this toward electrode-negative. It may be labeled "cleaning" vs. "penetration", in which case "penetration" is the more negative side. I'll have to search the machine to give better info.
[Edit... In the images I've found, the arc balance is on top right on the control panel, and clockwise is more electrode-negative.]
I would definitely go with a larger tungsten since you have that option, though that won't directly affect the issues you described. It just protects you form the tungsten overheating and "puking" into your welds.
Keep us updated, and when possible, put up a picture. They really are more valuable than words when diagnosing welding issues.
Steve S
Yes, 1/16 filler will work you to death trying to build a bead with aluminum. It looks like you're putting down a decent amount because aluminum expands with temperature, but then shrinks a lot when it cools (this, too, is the reason for the crater at the end, you need an extra dip or two as you tail off to compensate). A 3/32 filler rod will make a difference for you, and except for fine work on quite thin stuff, I use 1/8" filler almost exclusively for aluminum.
As for the 1/2" wide bead while not building height, does your machine have an "arc balance" control? You can narrow the bead a bit by adjusting this toward electrode-negative. It may be labeled "cleaning" vs. "penetration", in which case "penetration" is the more negative side. I'll have to search the machine to give better info.
[Edit... In the images I've found, the arc balance is on top right on the control panel, and clockwise is more electrode-negative.]
I would definitely go with a larger tungsten since you have that option, though that won't directly affect the issues you described. It just protects you form the tungsten overheating and "puking" into your welds.
Keep us updated, and when possible, put up a picture. They really are more valuable than words when diagnosing welding issues.
Steve S
Hey Cris, Sounds like you need to to try a thicker filler rod. If using the 1/16 rod, try feeding rod into the puddle instead of dipping. ( you should be able to see the puddle build up). As for the crater at the end of the weld, come off the power slowly and move you tungsten in around in a small circle pattern away from the center of the puddle. The main thing is you don't want to just come off the weld power abruptly and leave your tungsten stationary. I like to make a small S in the puddle at the end of my welds. Give it a try. Let me know if this helps.
Thanks, Sam
Thanks, Sam