i have a lenght of aluminium pipe that have to be bend
spec are 6061t6 2in diameter schedule 40 ( 0.154in wall thick )
my question is what minimum bend radius an alu pipe of the above spec should be
is there any trick for bending this type of alloy and temper without cracking the pipe
the problem is that i allready bought and cut to lenght the pipe
it will be bend on a real pipe bender not on a homemade jig
any info appreciated
I bent some 1" sch 40 in a 180 degree bend with 4" radius using a set of wooden dies in a small hyd press. I annealed the tubing in my barbeque for an hour on high, it was like butter but it workhardened up nicely after bending. If you are going to bend it more than 20-30 degree you will probably want to anneal it, the T6 condition may crack past that. You also want to go minimum 2x dia for a bend radius, but 4x would be better.
A hydraulic pipe bender should already have a die shoe with the correct radius of bend for that pipe. I know mine does.
I have done 2" 6061 in mine and it bent fine.
Was it T6? I thought T6 was not really good to cold form as it is pretty hard.
Yes it was T6-6061. The pipe benders have a very generous radius to the die shoes so it can handle it.
6063 is always better for bending if you have the option.
i need two 90deg bent on this pipe
the radius of bending wont be below 10 inchs for 90 deg angle
do i have to anneal if so how do i do it ?
if i have to anneal whats the best easy way to gauge the final temp of the aluminium
I would try a short length of material first and check for cracks and deformation. You should also be able to tell by the amount of pressure required to bend it. The 1" tubing I bent barely even registered on a
10t jack in the press. When I annealed the tubing in the barbeque the temp gage registered around 600 degree F. I put the tubing lengthwise on the BBQ and teh slot in the cover for the rotissery was just the right size to let the cover sit down fully. It might sit up a bit with the larger tubing but a bit of tinfoil wrapped around it should keep the heat in. I didn't notice any sag or distortion of the tubing, even after an hour.
If I had to do this, I would try to bend a sample bend on a spare bit of the same size stock before I would anneal anything, assuming a bender with appropriate dies was available. To anneal aluminum to near a dead soft condition, the cheap and dirty way is to soot the part with an oxy-acetylene torch flame, using just acetylene, then use the oxy-acet flame to heat the part until the soot buns off. You can quench it or not, it wont make much difference other than you will be able to handle it sooner if you quench it to cool it down.
No oxy-acet torch? Draw a bunch of squiggly lines with a Sharpie marker in the area you want to anneal. Heat area with a propane torch or other heat source until the marks disappear.
The heat treatment to get it back to a -T6 condition requires an accurate heat treating oven, but it will naturally age out to about a
-T3 or -T4 condition in a couple months (IIRC)
Cheers Trevor Jones
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