Failed weld on aluminum tube. Why?

Franko

Franko

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I had a project where I needed to weld some 1" x 2" x 1/8" aluminum rectangular tube. I utterly failed to do it.
I'm not much of a TIG welder but I can make fairly good looking welds on butt and T joints an varying thicknesses of material Using my Miller Syncrowave 210.

This is a diagram of the weld I was trying to make.

weld failure_1418.JPG

No matter how many times I tried, all could do was mess it up. I used up dozens of test pieces.
I practiced on this a day and a half and finally had to give up and make mechanical connections.

I tried everything I could think of, concentrating the arc on the horizontal part, moving faster, slower and all kinds of adjustments to my arc.
What usually happened is when I got the horizontal hot enough, the vertical would melt and I'd end up with a horrible gloppy bead.

I suspect the problem was caused by the different relative thickness of material down the middle of my bead as on the right drawing (B and C), which is an end view of the pieces.

I'd love to be able to make this weld. I'm planning something now that I need to.

Any suggestions on how to make this would be greatly appreciated.
 
Not clean enough, any type of coating, corrosion, not enough penetration???
 
Aukai said:
Not clean enough, any type of coating, corrosion, not enough penetration???
Click to expand...

Nope, they were clean. Brushed with a clean stainless brush and wiped with acetone.
I was able to make the T welds on the narrow (1" edge) of the material.
The problem was welding the end of one tube to the edge (corner) of the other (as shown in the diagram).
 
You've got the right equipment and sounds like you've got enough knowledge. Hope you have enough scrap aluminum to keep trying/practicing. Main amps setting, foot pedal technique, cleaning percent EN:EP, electrode point shape etc. all can make a big difference and a few more. Don't give up till you did it!

I once made an aluminum fuel tank out of .040 3003 aluminum GAS WELDED. It took me 1-1/2 years to learn to gas weld thin aluminum. I would try and give up, try something different and give up. In the end it came down to 2 main problems: heating the flux too fast and burning it and not being able to see the puddle good enough with the lens I was using. But I finally got it and installed that tank (actually 2 of them) in a homebuilt airplane without ever a problem.

DON'T GIVE UP, and as Keith Fenner says "git er done".

Aaron
 
first your gonna want your seams to be tight no gaps.
Then when you first strike a arc clean/preheat the joint with your torch run it along the seam at half pedal.
I always tack the corners so first it’s tack and second so you have material to start and stop at so you don’t have to turn the corner repositioning.
What’s the thickness of tubing?
Idk for some reason I like welding aluminum better than steel seems to flow better for me.
Are you doing any kind of weave pattern with your torch to disperse heat from part to part it helps with heat control.
Those inside corner joints should be harder than the flat joints.
 
Practice, practice, practice. When I first started I couldn't get anything to stick together and in time I was able to weld aluminum coke cans together, heavy end though. A guy I worked with could weld the bottoms and a friend of his could according to legend weld aluminum foil together. Granted I was using a really nice Linde machine and the experts set up the machine for me. Another thing when I first started was the focus on cleanliness, no oil and only use stainless brushes. So one time we needed to weld up a set of fork legs, the drain hole and extensions on the leg so we tool it to a local heliarc guy. Literally there was oil dripping from the drain hole and the welder said sure, took it over to the bench and welded it all up. No cleaning or anything took about 15 minutes for both legs. Did a real nice job but this welder had a lot of experience.
 
So just a bad looking weld or no penetration? If it's a pigeon-dropping looking weld, it's probably just practice, practice, practice. Your tubing is 1/8" thick wall, so maybe use around 150 A in AC for starters?

Bruce
 
What type of aluminum? A lot of stuff comes with mill finish that is actually a light anodized coating. This is almost always true for extrusions. Wire brush is not enough to remove this. And it has to be removed completely from the weld area. You may need to sand or grind off the coating and then acetone it. Go back and heavily sand the edge of the material and re-try. Also add more filler than you think you need initially. Once you get a large puddle of filler going it will proceed more easily.
Bruce is good on the number. 130-150 Amps should do it depending on how much penetration you need.
Robert
 
Thanks for the suggestions.

I'm pretty sure it was clean. I brushed it until it was shiny and scratched. It's always been good enough for other welds on the same material.
Test beads on flat material and test butt welds were average for me (pretty good).

The picture I showed isn't the position I was welding. It was just to illustrate the shapes.
I had the pieces clamped down flat and tight together so I was welding a horizontal surface.

It is possible my arc distance was too long. I remember the arc wandering.
 
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