Bending Aluminum Tube

6061-T6 will be difficult to bend. Recommend you use 6061-T4 or with no temper and then temper it.

Have you tried filling the tube with sand, tightly packed, cap the ends, and try the bend again? May or may not be enough...
I do know that filling a tube with sand before bending helps out quite a bit with wrinkling/breaking, and allows a more uniform bend. Cold working is my preferred method if I can get away with it. Otherwise, heat will be your friend, and enemy...

Somewhere between 500-700°F is your working temp with 6061 Aluminum (I believe).

What we used to do was soot the bend area with raw acetylene, then heat the area until the soot went away, no hotter. Allow the metal to cool slowly. The aluminum will be dead there. We never had to re-temper the metal. Bending may have a work hardening effect on the metal. Use a bending device like a conduit bender that supports the metal while it is being bent.

Here.

What is the centerline bend radius? What method are you using to perform the bend?
Even without the specifics, my first thought is the T6 temper makes it too hard/brittle.

Method that I heard about is like this, Filling tube with melt of low temp plastic or metals (something like LDPE) and let it solidify, Get it out from tube again by heating it after doing bending process.

NEVER resort to heating. You have no means of monitoring or controlling the process of heating. The metallurgical properties of material will get irrevocably damaged and the component will fail. T6 temper at the heat zone will not exist.

The following systematic process will definitely solve your problem.

• Anneal tube 570-770 F slow furnace cool
• Bending O tempered (annealed) tube should be very easy.
• Use Cerrobend filler material in case you have wrinkle or ovality problem during bending. (Cerrobend is an alloy of bismuth, lead, tin and cadmium. It has peculiar properties which makes it ideal filler for tube bending. It has a melting point of 158� F. that is much less than the temperature of boiling water. Cerrobend has been used successfully in the bending of tubing with walls as thin as 0.007 in. to small radii. Cerrobend conforms snugly to the inside of the tube that the tube can be bent as though it were a solid bar. This quality is due to the fact that Cerrobend expands slightly instead of contracting on solidification.)
• Solution heat treat at 960-1110 deg F for a period to be decided insitu by the heat treater and water quench. (MIL-H-6088)
• The tube after heat treatment will remain soft for considerable time and any dressing to remove distortion can be carried out during this period. The part can be refrigerated to delay onset of hardening.
• Precipitate harden at 320 F for 18 hours aircool, followed by 350 F for 8 hours and air cool.

You may try out getting material with condition O and avoid annealing. Also experiment with condition T4 material and do the Precipitation after fabrication.

Since Cerrobend contains toxic Cadmium and Lead an alternative material called Neylo 158 is marketed by www.neymetals.com.

What is the radius that you need to bend it to? I know a shop in SE PA that specializes in bending tubing. let me know if you need there number

Jim C

6061 T6 is a hard metal first you will have to fill the tube with sand tightly and capped and it has to be heated at the place of the bending you can heat it with a gas burner or furnace and it bend easily.

Regards

Aftab Ahmed

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T6 is Precipitated condition which give metal the maximum strength. Torch heating of the material will destroy the metallurgical structure at the heated zone negating the designer purpose purpose of calling for tube with T6 Temper.

Local heating of 6061 tube is an unscientific advice consequence of which will result in disastrous failure of the component.

Here's my personal story:

I unintentionally left 500kg of 6061 T2 tube too long in the store and it age hardened before i could get to bend it 90 deg 50mm radius. I had to anneal the entire batch!! so i marked each bend area with temp chalk (commercial bath soap also works) and heated the area on a furnace till the marker went brown +- 420 deg C, then immediately quenched, bent the tubes and sent them for artificially ageing at the supplier. The results were more than satisfactory for the requirements and had no problems at all.

Never left T2 alum alone from that day

Hope this helps

I have read somewhere that you should fill the tube with sand well packed and then bend it.