I'm practicing with my TIG on aluminum and trying to make nice looking welds. On Butt welding aluminum, it seems to melt away the aluminum instead of flowing together. I usually end up cramming some rod in there and get it joined, it forms a C shape and I have to build up with the rod in the C, sort of like piling a weld on a weld. I tried butt welding steel, it makes a puddle, both sides flow together and I can weld the 2 pieces together with or without filler rod. Is the aluminum butt joint supposed to form a puddle between the pieces like steel or should both pieces melt back making a larger gap to fill?
You have to make sure your edges are clean and oxide free for them to flow. Also, the specific alloy makes a big difference.
6061 and 6063 should never be flow welded together. You need a filler rod, 4043 or 5356.
5052 can be flow welded together, as can 3003, and 1100.
5086 should have a filler rod, either 5356 or 5556.
As long as the edges are touching you should get a good flow on a seam with no keyholing.
The aluminum I was practicing on was bought from the overpriced metals rack at the hardware store, not sure what alloy. I bought some angle and a piece of flat. I'm planning to soon order some 6061, 6063, 5052, and 1100, round & square tubing, sheet, angle, expanded aluminum... for projects around the house.
On trying to weld my hardware store alloy angle aluminum, the edges start out touching but melt back right away, leaving a gap to fill, then I get the keyholing. I think my angle is 1/16" thick, it may be easier to control melting if I started with something thicker. I'm guessing maybe a butt joint might take less amperage than a T or lap joint, could be part of the problem causing the melt away gap that starts the keyhole.
You are...are cleaning it perfectly clean...correct? And both pieces of aluminum are of the same alloy?
Aluminum WILL require filler rod. Steel is one of the rare exceptions to that rule,based on my experience.
Gunner
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)
What's that Lassie? You say that RogerN fell down the old sci.engr.joining.welding mine and will die if we don't mount a rescue by Thu, 26 Aug 2010 05:51:45 -0500:
It may be anodized. You need to sand/grind all surfaces that will be melted. And a little more wouldn't hurt.
If not anodized, you can use a stainless steel brush. A clean never used on anything else but aluminum prep. brush.
It may help to use the pedal in a 'pumping fashion' to grow a puddle, then let it cool, over and over again. If your welder has a pulser function, that can do the same thing.
When it starts I get a shiny metal on both pieces but it flows apart instead of together. Sort of like parting the ocean on the Ten Commandments movie, as I try to weld aluminum goes from touching to parted. I add some filler rod to one side and the other until I build it up enough to bridge. It ends up that I weld some 1/16" angle butt welded and the bead is almost a half inch wide. This is new metal, I clean with SS wire brush bought only to be used on aluminum.
I can run a bead on this stuff with no problem, I can even set 2 pieces back to back and weld them together without filler rod, but I'm not getting what I want on the butt welds, maybe I just need more practice. I'm trying to get a puddle instead of a key hole. I may have too high of amps melting away the metal instead of running a bead on the metal. I'll try on thicker aluminum and see if it's easier to learn on.
I think I may be using too much power, I have a piece of 1/8" and a piece of
1/16" aluminum and have been keeping it on the same amp setting most of the time, works well for some joints but butt welds seem to melt away too easily.
I tried running a bead on sheet steel, 22ga., and it was too easy to burn holes in until I lowered the amps to around 30 or so.
I've done a good bit of practicing on light metals and so far haven't plugged the welder into 230V yet.
That is one of the big problems with aluminum. You have a VERY narrow range of amps to work in, for each thickness and each TYPE of weldment.
Close to the end of a piece of alum..and you need significantly LESS power than you do in the center. Aluminum really transfers heat rapidly and in the center of a piece..you are radiating heat in 2 (or more directions) so need more heat. At the end of a piece..it only radiates in one direction..so you need less heat.
Im NOT a welder. Just a fumbler..and Ive found that with aluminum..I start low and work my way up until I see that faint "almost liquid" shimmer it gets and work from there. Quickly.
Doing it with tig is better at this than with MIG..because one can work the pedal finding the sweet spot. My old Squarewave 300 has digital readouts for actual amps being delivered at the torch...and Ive learned to write thosed down until they stick in the spit wad I call my brain. Then I can do a setup and set those numbers as the max output and work around there, with pulse and all the other fun things one can use on a big full function welder like that and not (well..not too often) blow holes in things.
This can be a problem for me though..as I tend to dawdle around at first and since you are constantly pouring in heat..it can melt rather faster than you expected.
Ive got an old Miller Mig35 and a Cobramatic feeder for aluminum mig and Ill play with it a bit on scrap before trying to weld aluminum. And remember..its Fast! You cant sit on the weld and putter around else it drips onto the floor..or the tip of your boot.
Gunner
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)
What size of Tungsten are you using Roger? For 1/16" Al, you shouldn't be using anything than a 1/16" tungsten if you haven't yet developed a decent feel for it. Same with the filler rod.
Roger - what you say fits in exactly with Ernie's advice which I found exactly accurate so many years ago... - which is
You want about 40A per millimetre / 1 Amp per thousandth of inch ("thou") for steel.
Then I looked up the thickness of 22Ga - and what do we find
formatting link
Ga Thickness
22 0.0299[inch] (0.76[mm])
So 30A for 0.75mm is exactly on the Ernie recommendation.
For refining TIG welding. I found that finding the lowest amps you can do the weld with is good practice. Turning down the amps bit by bit. You can end up with a very small narrow cool full-thickness-penetrated weld at a reasoanble speed. When you've got to that point where any lower amps simply won't melt a weld-pool and you've been welding well until then, you then win "the prize", which is that you choose what conditions you want to weld with.
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