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greywynd
12-13-2005, 09:21 AM
Ok, I have some 6061-T6 that I'd like to do some bending in order to make some of the projects on my list. Is this something that I can bend easily without any treatment, or should it be heated or anything? Most of what I would be bending would be 1/4x2" flat stock, and the bends would be to 90 degrees. Hoping someone has some experience with this rather than scraping a bunch of material.

Thanks,
Mark

3 Phase Lightbulb
12-13-2005, 09:43 AM
I thought you have a TIG welder? You could TIG that 6061 together in the corners instead of bending it. I think 1/4" might be too thick to bend at 90 but I'm not sure.

-Adrian

Evan
12-13-2005, 09:52 AM
You will need a bend radius equal to about 1.5 to 2 times the thickness of the material for T6 temper. You can bend it sharper but it will weaken the material. You can't bend it with no radius. It will crack.

Your Old Dog
12-13-2005, 09:52 AM
At the place where I buy my stock they told me either barstock or sheet bent more reliably but I don't remember which. I always heat with a propane torch anyway to keep fatigue done to a minimum. If I had tig it wouldn't be a consern of mine http://bbs.homeshopmachinist.net//biggrin.gif

PTSideshow
12-13-2005, 10:22 AM
I vote with all of the above, you can bend sheet either with a brake or improvised brake without power. The barstock not only will have a radius but it will pucker on each side of the edges of the bend (outward). And some times even with heat it will fracture later rather than now.

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Glen
Been there, probally broke it doing that

jcurrell
12-13-2005, 11:32 AM
Take an acetalene torch with black smoke along the bend line, then go with regular flame till the black sut is burned off, and bend.

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Evan
12-13-2005, 11:33 AM
Keep in mind that heating the aluminum will reduce the strength.

lbender
12-13-2005, 01:11 PM
greywynd,

The tightest recommended 90 degree bend for 6061-T6 1/4" thick bar at room temperature is a RADIUS of 7/8". A small radius runs the risk of fracture during bending, or worse yet, fatigue failures in service. The recommended method for small radius bends where the T6 strength is required is to solution heat treat (990F), cold water quench, bend, then age to T6 (350F). Heating above 350F to bend will lower the strength in the heated area.

andy_b
12-13-2005, 07:09 PM
i had some 1"x1/4" Al i bent 180* in about a 1" radius. i had to heat it to do it without the stock cracking. it still seems plenty strong to me, but i have no idea what alloy i started with or exactly how strong it still is. i bought the piece at the local orange home improvement store.

i don't know if this helps.

andy b.

Your Old Dog
12-13-2005, 08:37 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
Keep in mind that heating the aluminum will reduce the strength.</font>

I once made a 6 element 2 meter beam out of 1/4" aluminum rod. I used Wonderrod to solder/braze it to the boom. Not more than 2 days later and every element was bend down at least 30 degrees from the weight of crows !! Really smoked me off http://bbs.homeshopmachinist.net//biggrin.gif

timz1999
12-13-2005, 08:39 PM
you need a bend radus of 2 X metal thicknes for sheet stock. 6061 t6 is used on alot of aircraft. i have never bent any thick stuff they don't let you use tourches around the aircraft eather. my last word of advice is try it and if it stress cracks weld it.

Evan
12-13-2005, 09:07 PM
2024 and 7000 series is mostly what is used on aircraft. 2024 is 50% stronger than 6061 at the same temper. I never saw much if any 6061 used on aircraft except for the rare welded aluminum parts.

DR
12-13-2005, 09:32 PM
According to my Alcoa Aluminum data book...

Cold bending 1/4" thick 6061-T6 the bend radius should be from 3/4" to 1".

By controlled heating it can be made to bend easier. If the heat is maintained only for the given times no more than 5% loss of strength will be experienced. 375F for 1-2hr, 400F for 30min, 425 for 15min, 450 for 5min.

Rivet machines dimple aluminum aircraft skins for countersunk rivets using low heat like above to avoid cracking.

greywynd
12-13-2005, 10:59 PM
Thanks guys, this helps a lot. (I do have a tig welder, but sometimes things look nicer with a bend instead of a sharp corner.) If I try this and it works, I'll still be using the welder too....this is just one of those "I wonder" kind of deals....I have one of the cheapie import metal benders that I haven't got a whole lot of use from yet, and may have a couple of things that I can use it for now. http://bbs.homeshopmachinist.net//wink.gif

Mark