Aluminum tube bending

We have your RMB #150-110 machine which is a great asset. Lately we have been having a problem with bending square aluminum tubing ( 1 1/4 " X .125" wall ). We special order 6063 T4 and some times when bending, we get wrinkles on the inside of the bends which appear like " knuckles ". We are using 4" and 3.5" radius dies. I have tried slower speeds when bending and have left the material outside in the sun, hoping that the build up of heat would help. The metal merchant assures us that all the material supplied is T4. Could there be an adjustment on the machine to remedy this problem or is there some thing else that I am doing wrong ?

No Baleigh connection, but have you had a hardness check run on the stock to see if it matches the range expected for a T4 material? And I wouldn't expect a tiny bit of warming to do anything, but if you can safely take a rosebud torch and blast the OUTSIDE of the bend transition area as it's moving around the die to both expand the Al and to get it up to ~200-300F it might encourage more outside stretching rather than buckling on the inside. Again, only if this can be done safely!

It's difficult to bend square tubing without some wrinkling if you don't have a mandrel bender. Going to a softer temper will help but, with a tight radius, that material you're compressing on the inside of the bend has to go somewhere. Increasing the bend radius will reduce the amount of deformation, annealing will help to some degree but neither idea changes the fact that when you bend a tube you stretch the outside and compress the inside.

I don't think it's anything to do with the bender--we have the exact same machine and bend lots of round tube and pipe with no issues. But I know that we'd have the same problems if we tried to bend square tube....

Thank you for the comments. With this machine, the rosebud trick is not an option because of the nylon guide. We have been getting nice bends with no distortion on the inside of the radius at all and it's frustrating when on some bends the wrinkles appear. The best info that I can come up with is that over time aluminum tubing will increase in hardness but looking at this batch of tubing, it all looks to be the same. With T5 I have experienced shearing of the material. As per instructions we use a liberal amount of wax for lubricant. Hopefully the next batch of material may be of uniformed hardness. In today's world, it's hard to know if material is made in the USA or not. As with steel tubing, the merchant will tell you that the tubing is U.S. made but what they don't tell you is that the tubing is made from imported sheet steel.

It is my understanding some types of aluminium get harder over time
So a batch comming straight from production is softer as old stock
The time it takes is a couple of weeks
Try to aneal a piece and see if it helps

Perhaps someone more knowledgeable can comment

Peter

Peter from Holland said:

It is my understanding some types of aluminium get harder over time
So a batch comming straight from production is softer as old stock
The time it takes is a couple of weeks
Try to aneal a piece and see if it helps

Perhaps someone more knowledgeable can comment

Peter

Click to expand...

Yes age hardening is very common. It is a common call for customers to crack their tube

Hello, my name is Shane. I am one of the tube bending gurus here at Baileigh. Give me a call direct, I have lots of tips and tricks to help you bend aluminum. 920-482-3220

Please share some ideas here....

Baileigh inc said:

Hello, my name is Shane. I am one of the tube bending gurus here at Baileigh. Give me a call direct, I have lots of tips and tricks to help you bend aluminum. 920-482-3220

Click to expand...

Fresh aluminum is always important
Using roller counter dies also helps
A generous radius lowers the risk of splitting or cracking
Be mindful of the temper T-0 to T-4 likes to be bent, the closer you get to T-6 you raise the risk of cracking