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Posted by Jon Elson on October 12, 2008, 2:18 pm
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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.
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.
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. I
think preheat is going to be 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,
Jon
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Posted by Winston on October 12, 2008, 8:28 pm
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Jon Elson wrote:
> 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.
When the pro's get here they are gonna want to know, among
other things:
1) How many amps are you using? Aluminum requires lots of amps.
(You should have 150 amps available, minimum).
2) AC? DC? Polarity? Aluminum likes AC for cleaning and penetration.
3) What techniques are you using to remove any anodize,
surface oxidation and gunge? TIG needs clean, clean, clean
for the workpiece, filler and tungsten.
4) What problems are you seeing? Cracks? Lack of fusion? Burn through?
5) Equipment -- do you have a color filter to allow you to
see the puddle?
6) Are you welding in position or out of position?
7) Straight argon for shielding gas, right? What flowrate?
8) You are regulating current using a foot pedal, yes?
Have you reviewed Ernie Leimkuhler's excellent TIG FAQ?
--Winston
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Posted by Jon Elson on October 12, 2008, 11:44 pm
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Winston wrote:
>
> 1) How many amps are you using? Aluminum requires lots of amps.
> (You should have 150 amps available, minimum).
Yup, that's about where I set the dial.
> 2) AC? DC? Polarity? Aluminum likes AC for cleaning and
> penetration. 3) What techniques are you using to remove any
> anodize,
AC, and I've tried a variety of wave balance settings.
> surface oxidation and gunge? TIG needs clean, clean, clean for
> the workpiece, filler and tungsten.
The metal is quite clean, but I didn't use solvents on it. I did
brush with a stainless wire brush I use only for aluminum. I
haven't been using much filler.
> 4) What problems are you seeing? Cracks? Lack of fusion? Burn
> through?
Much lack of fusion, the sides of the joint pull away (melt back)
leaving a gap.
> 5) Equipment -- do you have a color filter to allow you to see
> the puddle?
I have an auto-dark lens with variable darkness, and I can see the
puddle pretty well.
> 6) Are you welding in position or out of position?
Not clear what you mean, here. I have the seam laying flat
horizontally. Due to the piece being 12 feet long, there are some
limits, but I could set this up so the surfaces to be welded are
vertical.
> 7) Straight argon for shielding gas, right? What flowrate?
Straight Argon, and I've tried several settings. Usually I can get
good welds at 5 CFH, but I have turned it up to 10 with no change.
I am using a gas lens in the torch.
> 8) You are regulating current using a foot pedal, yes?
>
Yes.
> Have you reviewed Ernie Leimkuhler's excellent TIG FAQ?
Yes, but not recently. Maybe I should reread it.
Thanks,
Jon
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Posted by Winston on October 13, 2008, 1:18 am
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Jon Elson wrote:
(...)
You don't really see a weld 'pool' at all?
I was cruising the web just now and noticed that the accepted
practise is to add ~5 to 7 percent filler to join 6063 in order
to prevent cracking. If there is no pool to dip your filler
into, that is going to be a big show stopper.
We have now exceeded the limit of my tiny knowledge on the
subject so I think you should speak with those that really do know.
Your best bet is to subscribe to sci.engr.joining.welding and ask
the experts. I see that Ernie Leimkuhler was answering questions
in that newsgroup as little as 4 hours ago. Ernie is who God asks.
You might want to compose your question so that the experts
don't have to work unnecessarily.
Were I you, I would repeat the question you asked here but I would
add the details that you mentioned just now, plus any details you
can add that seem useful. Use of High Frequency and Pre-flow and
post-flow settings for example:
"I'm attempting to TIG weld some 12' long box tube 6063
1 x 1-7/8 x 1/8" wall (1 x 1.875" outside dimension) using 3/64"
dia 5356 Mig wire filler.
Just as I begin to weld, I see the edges of the joint pull away,
forming a gap. I expected them to form a pool but they don't.
What could be the issue here?
Tungsten: 3/32 Zirconiated
Gas Lens: Yes. 5 CFH straight Argon. Tried 10 CFH with no change
Filler: 3/64" 5356 MIG wire
Prep: Stainless Steel brush used only for aluminum,
No solvents, No Vee prep.
Welder: Lincoln Square-Wave TIG 300 with foot pedal
Torch: Weld-Craft water cooled with Miller cooler
Position: Flat on the bench, horizontally
Polarity: AC Squarewave. Tried different balance settings.
Helmet: Autodark lens but no Anti Sodium flare lens
High Freq: [You do have that turned on, right?]"
Best of luck and please keep us posted.
--Winston
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Posted by Jon Anderson on October 13, 2008, 2:33 am
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> Jon Elson wrote:
> Just as I begin to weld, I see the edges of the joint pull away,
> forming a gap. I expected them to form a pool but they don't.
> What could be the issue here?
It's been my experience that aluminum often will do this.
I'm more of a 'just do what works' type and less of a follow
the book welder, what I've always done is just stab the
filler rod right smack in the middle of the two. Once you
have the two sides joined in a common puddle, you're on your
way. On thinner materials, I sometimes melt off a small blob
of rod right on the joint, and melt it into the material as
I bring the heat up.
Jon
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>
> 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.