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Thread: Bending 6061-T6 pipe

  1. #1
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    Bending 6061-T6 pipe

    The other day at the LWS/metal vendor's shop I ran into a discussion of bending aluminum pipe. The contractor who was doing the work was completely sure that 6061 T6 pipe won't bend in conventional external shoe types of benders- no matter what.

    However, he was having a hard time on his hand rail spec. for his job as the entire pipe spec was limited to 6061 T6 and 6063 was specifically prohibited. So he was looking for 'another' alloy to try to run by his engineer to get the returns bent in a single shot - but believed he couldn't do that with 6061 T6.

    I have been bending 6061 for years, always successfully (after learning to smooth the die) using the large radius dies of the Greenlee 555 elec/hydraulic bender. So I chimed in to offer to explain how it can be done - pretty easily too.

    He didn't seem to have much faith in my ideas or reports of experience until the owner mentioned he'd been selling me 6061-T6 pipe since the late 1970's and that it was pretty likely I had some idea about what I was describing.

    If there are any boat builders, fabricators or others on the Forum who believe the myth that 6061 won't bend in conventional benders- not sure about the super tight radius off road roll cage bender's for tubing with very tight radii?- then I'd like to mention what is needed.

    Using an appropriately sized sanding bulb, roller, pad, wheel or 1" belt sander- simply sand the entire die surface to 240-320 - then polish with a cloth wheel on edge with metal polish.

    When you go to bend make sure the 3:00 & 9:00 surfaces of the die are smooth with the rest of the interior curve, and lube the pipe and the die until it drips. Can use a variety of lubes- Spray Pam, cooking grease, axle grease type products, engine oils- heavier wts best, or wax, or even the machinist's friend; lard.

    The failure of 100% or all my early bends was from the sides of the die galling the pipe side walls, gripping the pipe so it could not flow into the bend and tearing the pipe.

    the pipe is plenty malleable, the alloy will form/deform if the radii isn't too tight, and that's all there is to successfully using conventional (rigid steel conduit sized) bending dies on 6061-T6 pipe.

    Lots of shops in our location claim that 6061 won't bend- always "breaks". I'd wager this is because the die is galling and about fusing the side wall of the pipe as it 'eggs' in the bend and the pipe is simply torn - not snapped because its too fragile to bend.

    Don't know if the contractor got his returns in 6061 or 6063? but last evening a friend and I put a piece of 2", Sched 80, 6061-T6 in a 'triple nickle' and it bent just as smooth as steel would have. I'd polished the 2" die and we lubed the whole show until it dripped and the bend took a few seconds. The pipe is flawless- except for a tiny, thin line along the pipe sides at 3:00 and 9:00 (near the edges of the female die's 'cup') where the pipe had started to seize to the die!! Lucky for us it didn't get wide enough to stop the pipe from moving into the bend.

    Hope to add to the knowledge base of anyone bending 6061 aluminum alloy pipe. Because of the copper alloying material in 6063, its not really as corrosion resistant as 6061 and if immersed for long will simply corrode away.

    Cheers,
    Kevin Morin
    Kenai, AK

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  3. #2
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    Re: Bending 6061-T6 pipe

    You can bend 6061 aluminum like a wet noodle,, if it is in the proper heat treat,,
    similar to any decent pocket knife,, you can pick up a 1/2" wide 1/8" thick piece of A36 steel that is a foot long,, and bend it with your hands.
    Carburize the same piece, and quench it, the same part will snap like glass, like the pocket knife.

    Take a piece of 6061 T4,, bend it the way you want, then you can heat treat it (precipitation harden) then you will have bent 6061 T6.
    BUT, screw up the precipitation treatment (too long of time, wrong temp, etc.,,) you end up with 6061 T0,, which is ultra weak.

    So, it is not easy, but it is done every day.

    When you "bend" the part, the grains of metal must slide past each other,,
    The precipitate is a different metal that will collect at the grain boundaries, and "lock" two grains so they can not slide past each other easily.
    It is kinda like giving the metal arthritis,, ask any old guy what his joints feel like,, this is the same thing!!

    If you bend the part while the precipitate is not at the boundaries,, the part will bend much easier,, or no arthritis,,

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  5. #3
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    Re: Bending 6061-T6 pipe

    What sweet said, it's mostly the heat treat that determines if it can bend or not.

    6061-t6 will bend, but how much depends on th setup. I know 1/4" alum flat bar can bend about 15 degrees fine, that is going cross grain, not with. At 30/35, boom. That is also bending on a 12x die, not the standard 8x.


    If I remember right, there was a bicycle builder on here who would bend 6061 t0 to shape, weld, then heat treat.

    Sent from my SM-G960U using Tapatalk

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  7. #4
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    Re: Bending 6061-T6 pipe

    'sweet, country metals,
    I was discussing bending T6, not building an oven, and not heat treating.

    6061-T6 is the title, of the thread. Not heat treating 6061 after bending it in the non-HEAT treated state!

    I don't know many (one man fab) shops who can heat treat an assembly or even a single pipe! I was trying to address the topic of bending the material as it comes from the metal vendors/mills in the T6.

    I'd love to have a vendor (in rural Alaska) who would supply 6061- in an unheat treated form, then own an oven and (complex controller) equipment that would heat treat it once I had the forms I needed? But short of all those luxuries- I just bend it as it comes and enjoy the results.

    I bend 6061 T6 flat bars at 12T=D or 6T =R on the same bender I use for pipe. The die (home made to fit 555 Greenlee) is lubed (and lined with UMHW) to allow the bar to flow into the bend and I get 90's and even 180's: anytime. 4" x 1/4" being especially useful for marine coamings for hatches, companionways, liners for lightening holes and misc. other flat bar frames; it bends reliably and w/o failure.

    My remarks are about bending the 6061 alloy as it's most commonly supplied: in T6 temper.

    Cheers,
    Kevin Morin
    Kenai, AK

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  9. #5
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    Re: Bending 6061-T6 pipe

    Edmonton Exchanger forms thick steel and apparently the shops where the forming are done are quite dirty because of all the graphite they use when forming. They have a 3000 ton head press and can roll up to 12" thick. I don't know if graphite would work for bending aluminum but you can buy dry graphite spray that's easy to apply. Pretty hard to dispute it can't be done if you've been doing it for years.

  10. #6
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    Re: Bending 6061-T6 pipe

    6061-T6 easily bent on a JD2 model 32 bender. No die polishing. No lube. No deformation. No cracking. No wrinkling. Lube is not recommended per JD2.


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  12. #7
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    Re: Bending 6061-T6 pipe

    So I have a m54 bender from JD2 and when I bend alum pipe is gouged the hell out of the pipe. I rigged up a plastic piece to replace the second guide and I no longer get the gouging.

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  13. #8
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    Re: Bending 6061-T6 pipe

    Quote Originally Posted by Country Metals View Post
    So I have a m54 bender from JD2 and when I bend alum pipe is gouged the hell out of the pipe. I rigged up a plastic piece to replace the second guide and I no longer get the gouging.

    Sent from my SM-G960U using Tapatalk
    JD2 sells Delrin inserts that bolt on in place of the follow block inserts - they don't recommend bending aluminum on the standard inserts.

    https://www.jd2.com/pd-inserts-gen-3-delrin
    Who is John Galt?

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