need help welding 6063 extrusion

Hello, all,

I got myself roped into a project making up frames for panels to protect stained glass windows when a church sanctuary is used for a gym during the school week. We went and got $800 worth of 6063 rectangular extrusion from the metal yard, and I'm having an incredibly tough time TIG welding this stuff. The main problem is the weld PUDDLES (TWO!) don't want to fuse, and I end up with the two pieces melting away from each other. (I did do a very respectable (for a newbie) weld on 2 pieces of 5052 1/16" without filler. I used a 1/16" Zr electrode, otherwise very similar setup, prep and technique.) I don't have a lot of material to spare while fooling around, either, we bought them out of an odd size, 1 x 1 7/8 x 1/8" wall. (That's 1 x 1.875" outside dimension.)

I just got in some 3/32 Zirconiated tungstens, a gas lens set for that size, and some 3/64" 5356 MIG wire for filler. I got a pretty good fit-up of the edges after a whole bunch of fooling around with my 4x6 hor-vert bandsaw. I tried to weld this with without grinding a vee to fill, maybe that is part of the problem, although my TIG book suggests that is possible up to 1/8". I have a Lincoln Square-Wave TIG 300 that as far as I know is working perfectly. I have a Weld-Craft water-cooled torch with a Miller cooler. I know that MIG wire is not the perfect thing for TIG, but I'm not even sure I need filler wire. (I also have some 4043 filler, and will try that next.) What Argon flowrate should I use with a #6 or #7 cup and gas lens? Welder settings are 150 A max, AC, continuous HF. What wave balance would be good for a Zirconiated tungsten?

Does anyone have any advice on what to do, common newbie pitfalls, etc? Obviously I can't support the back of the weld inside the tube. Is preheat needed? I have a Bernzomatic propane torch and an Oxy-Propylene set (essentially generic Oxy-MAPP) but have no idea how much pre-heat to use. I did try welding a couple pieces of tiny scrap, and that went a LITTLE better, I did actually get fusion along part of the seam. That sort of supports the idea it needs preheat. I KNOW I'm in way over my head, here.

Thanks in advance for any help you can offer!

Jon

Reply to
Jon Elson
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Two things I can t hink of to try: 1. you didnt mention cleaning. wire brush the aluminum thoroughly before welding. Also try a higher heat setting. too low a setting and it takes too long to make a puddle. you want a puddle quickly, before the metal around has a chance to heat up. if you dwell too long you will melt all the way t hrough. you must have enough scrap to practice on until you get it. good luck DickP.

Reply to
dickpereli

I second the cleaning. You might use sandpaper to clean followed by a stainless wire brush just before welding. Aluminum oxidizes really quickly so it is good to give it brush just before welding. And aluminum that has been sitting around for some time will take quite a bit to get all the oxide gone.

Nothing wrong with using Mig Wire. But you might have better luck with thicker filler. Something that you can stir the puddle with. I generally try to use filler wire that is about the same diameter as the material is thick.

; Dan

Reply to
dcaster

I'll third the cleaning- it's hard to clean aluminum too much. You do want higher heat to form a puddle quickly- run your bead fast, swiping the filler into and out of the puddle (adds more metal than quick dabs).

Anodized aluminum won't weld, as the anodized layer has a much higher melting temp than the untreated aluminum under it. By the time you get it to melt, you've had the rest of the aluminum drip out.

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this page has some good info

good luck!

Reply to
TinLizziedl

Why 5356? Was it cheap?

4043 is more forgiving of dirty metal. It's silicon content gives it better wetting than 5356.

You HAVE TO add filler metal with 6000 series base metals. Any attempt to flow the metal together without filler will just lead to cracks.

You have to be aggressive with the filler metal. When starting a bead, melt the end of the rod off into a tiny ball sitting in the joint. Then heat the ball directly until it wets out to both pieces.

If the weld filler metal won't wet out then either you have bad metal or insufficient shielding gas.

You are going to be pushing a 3/32" tungsten, even a zirconium one. With that material you want around 180 amps.

12-15 cfh gas.

Most AC TIG machines have a base setting or "balanced" setting for the AC wave balance. On Miller TIGs it is a 3 on the 1 - 10 scale.

You shouldn't need any special wave balance to weld this.

As long as you are sure that it is 6063 and not something difficult like 7075.

Reply to
Ernie Leimkuhler

Ernie Leimkuhler wrote: Thanks for the reply, Ernie, I was hoping to hear from you (and your always expert advice)!

That's what my Lincoln GTAW book said to use for

606x, but I have since found many references saying 4043 is better for several reasons.

So I see!

Yes, now that I've experienced a crummy weld with the 4043 (couldn't get any sort of fusion started with the 5356) I see this is the case. I just filed the seam and filled with 4043, and it definitely is working better.

Oh, that's good hint! Thanks!

OK, someone else suggested going up to 20 CFH, and then working down. I just tried 15 CFH with "OK" results. I am using a gas lens. I'd be scared of

180 Amps, I am near the edge of turning the whole thing into a blob at 150 max, and not using all of that via the pedal. I don't have a large selection of tungstens, other than the EWP that I bought when I started, and have never used again! So, I don't think I have any 1/8" tungstens but the EWP.

I think that's the same on the Lincoln square wave.

It is extrusion, and I'm pretty sure the scrap I'm practicing on is 6062, and the extrusion was said to be 6063 by the metals yard. I think the big thing here is solvent cleaning before wire brushing (I had assumed the wire brush would remove any oils, etc.) and your suggestion of using LOTS of filler. To end up with a flush weld, I will have to file an even bigger groove than I have been doing. But, I am making progress!

When I start to work on a piece, and am pre-heating it with the arc, I get some smoke, and it leaves a black deposit on the aluminum. If there's too much of that, that area becomes un-weldable. Any suggestions?

Thanks,

Jon

Reply to
Jon Elson

You should clean your wire brushes regularly with solvent as well. I prefer Acetone myself. Always solvent clean your work piece before contacting it with your brushes as well. When I worked aircraft aluminum years ago, they vapor degreased all our files, scrapers and brushes for us daily.

If your brushes become contaminated with oil or grease, as the eventually do, they will leave a greyer overcast to their finish. Look for a whiter metal finish. If you are not familuar with this color change, experiment a little. It's not difficult to learn, and is very helpful when welding all types of aluminum.

Reply to
Watson

You might have another problem here. If the material is clear anodized you will definitely have trouble welding it. You have to mechanically remove the anodizing with a flapwheel or heavy wire wheel, before welding.

Reply to
Ernie Leimkuhler

OK, this didn't occur to me before, but I did clean the wire brush. I think my problems are at least as much technique as cleanliness, but every correct step helps the final result. Using 4043 filler I am now getting fusion of the two sides, but poor penetration. Ahh, well, I have to work on that, a fine line between no penetration and globs of molten metal on the floor. Im doing these test pieces af aluminum sheet without any backup as the rectangular tube has no support on the back (inside) either.

Jon

Reply to
Jon Elson

No, I'm sure this stuff is NOT anodized. The scrap I'm practicing on, as well as the rectangular extrusion, is as it comes from the mill. The surface finish alone tells me it is not anodized. It might have some kind of polymer or oil coating to protect from corrosion, though, or just contamination from sitting around.

OK, now that I know a deep Vee groove is going to be needed, what do people use to grind these bevels? A flap wheel? Anything special to prevent contamination? What abrasive to last a while without clogging, or will anything do? I saw some interesting disc flap wheels at the welding store yeasterday, but didn't know what flavor was best. I should have asked.

I got a decent filled weld, but without significant penetration. Now that I have gone that far, I have to up the current and try to make the weld penetrate. Much worry that it will all go blop on my feet!

Jon

Reply to
Jon Elson

I usually use an aggressive double cut file to vee edges, (new or grit blasted clean) as aluminum cuts very easily.

On aluminum over 100amps I'll use 1/8" pure tungsten and usually take the square wave as far out of balance as the material will allow (I usually can't get to 70 percent electrode negative, max penetration). I can usually keep it from balling much, getting a more focused arc and narrower bead.

Tack with 40XX filler (wets well, but lower strength)

Weld from tack to tack using material of choice (5XXX fillers are tougher to use but can be anodized for color match and are stronger as welded)

Don't puddle around on 6063, use enough power to move at a good pace if you're tig-ing.

All of the above posts on cleaning etc. GOOD!

I'm not a fan of grinding anything I don't have to but aluminum wheels are pretty common now, also the 1/4" carbide grout removal burs (RotoZip) available at home centers are very aggressive and make short work of off hand metal removal.

Matt

Reply to
matthew maguire

I forgot something,

Ernie is right about the 3/32" Zirc tungsten I like 1 to 2 percent lanthanated for a doped tungsten that will keep a point. I gave up on zirconium on aluminum because instead of balling it seemed to grow multiple "warts or bumps" and the arc looked really goofy when that happened. Anyone else ever have this happen or is this just because I use a cheap "Prostar 2% zirc for welding....)

Also you can "choke" or focus the arc a bit more by using a smaller cup, for 1/8" material the "holy grail automated weld" bead width would be between 1/4" and 5/16" wide. I can't do that very well but the closer you get the better things look.

Your Lincoln square wave is going to have a "VERY" aggressive AC arc over

100 amps so 130 to 150 should be OK. It's just Lincolns' idea of how an AC square wave should work, but some folks really hate the loud machine gun like sound, and after passing 180amps things start to rattle around on the bench-top or weldment, kinda wierd.

If you get soot on arc starting, your surface, cup, tungsten or gas is or are contaminated. If you get black specks in the bead your material is contaminated or you pulled something up to the tungsten.

Matt

Reply to
matthew maguire

Also, check to be sure you are getting some pre- and post- Flow gas!! Before you start arcin-n-sparkin on the workpiece, set your shielding gas to flow for a set amount of time after you stop welding (I use 10 to

15 seconds) to cool the weld, and be sure your gas starts flowing several seconds BEFORE your arc starts. The prime cause of quick contamination on clean material is lack of shielding gas at the moment the arc goes on (IMO).

Hope that helps!

Reply to
TinLizziedl

Yes, of course, about 7 seconds pre, and 15 seconds post. Actually, I may be getting more than the setting values.

I still keep hitting the weld with the electrode, or sometimes my filler wire hand shakes and it touches the electrode and makes a HUGE glob on it. So, that's MY source of contamination. I'm getting better now, I have actually done a couple welds without ONE contamination incident. But, I still got a ways to go. I've completed 16 welds on the real workpieces this weekend, so I am definitely on the way on this project.

After some comments by Ernie (I think) I went up to 1/8" Lanthanum electrodes, and these do seem to work better than the 3/32 Zirconium ones. But, maybe it is just my improving handling of the torch. I got two of those 16 welds that I started well and then the filler just flowed into the joint, and I did the whole 2" weld in 15 seconds once the work was heated. The rest of them, well, I just won't talk about them!

Jon

Reply to
Jon Elson

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