Bending brake capacity: 2024-T3 vs. mild steel?

[Ihab Awad]

Hi folks,

Most bending brakes rate their capacity by the thickness of mild steel
that can be bent. How does this relate to capacity of 2024-T3 aluminum?
So, what aluminum thickness can a 16ga, 20ga, 22ga, ... brake handle?

Should I simply multiply by the ratio of the yield strengths? That
somehow seems like an oversimplification.....

Thanks a lot. Peace,

Ihab

--
Ihab A.B. Awad
email: < firstname dot lastname at gmail dot com >
Palo Alto, CA, USA

[guynoir]

According to American Machine Tools, you are correct.
http://www.americanmachinetools.com/tensile_strength.htm

More important considerations are bend radius and springback. Most press
brakes come with sharp upper dies and 90° "vee" lower dies. Neither work
very well with hardened aluminum alloy. For aluminum, you need a "U"
channel in the bottom die, and a radiused upper die. 1/8" radius is a good
general purpose choice for the upper die.

To get a 90° bend in 2024 aluminum, you have to over bend it by about 7° to
accomodate springback. For 7075 T-6 it is 20°. This can't be done with a
90° "vee" die.


Ihab Awad > wrote in news:d9KdnZNva5hK7j_fRVn-
:

> Hi folks,
>
> Most bending brakes rate their capacity by the thickness of mild steel
> that can be bent. How does this relate to capacity of 2024-T3 aluminum?
> So, what aluminum thickness can a 16ga, 20ga, 22ga, ... brake handle?
>
> Should I simply multiply by the ratio of the yield strengths? That
> somehow seems like an oversimplification.....
>
> Thanks a lot. Peace,
>
> Ihab
>



--
J Kimmel

www.metalinnovations.com

"Cuius testiculos habes, habeas cardia et cerebellum." - When you have
their full attention in your grip, their hearts and minds will follow.

[Ihab Awad]

guynoir wrote:
> http://www.americanmachinetools.com/tensile_strength.htm

Ah, thank you!

> More important considerations are bend radius and springback. ...

Thanks again for the very helpful info.

> Most press brakes come with sharp upper dies and 90° "vee" lower
> dies. Neither work very well with hardened aluminum alloy. For
> aluminum, you need a "U" channel in the bottom die, and a
> radiused upper die.

That's quite interesting. Would the geometry of this bend be such that
the (presumably rounded) edges of the U channel would "wipe" or slide
against the aluminum as it is pressed in between them by the upper die?
If so, does this validate the approach of this homebuilder --

http://www3.sympatico.ca/murray.j/tools.htm

His idea is that the hinge line of his brake need not pass directly
through the exact meeting point of the apron and bed surfaces -- the
metal will slide across the apron to compensate. Thus he is able to use
a series of hinges to support the apron all along its length, and can
therefore get away with a less-stiff apron.

If this builder's idea is correct -- and validated by the geometry and
usage of press brake dies -- why are not more industrial bending brakes
built to take advantage of this? Or, what am I missing?

Thanks a huge lot. Peace,

Ihab

--
Ihab A.B. Awad
email: < firstname dot lastname at gmail dot com >
Palo Alto, CA, USA