Re: aluminum grades

Sven:

Your idea here is right on. The strength of AL is about 1/3 or 1/4 that of
steel although both vary quite a bit. So under axial loading, straight pull,
you're right. But from Dave's description I suspect his application is in
bending. This is the most common loading which breaks stuff. If so the
stress is defined by Mc/I, M is the moment and c/I is related to the inverse
of the thickness cubed. With the cubed in there the stress goes down rapidly
as the thickness increases. (You know this :-) but there may be some on the
list it'll help.)

For machine tools though, stiffness is really nice and since they aren't
moved very often weight isn't a priority. If Dave is breaking brackets I
suspect he should make them, as you say, 3+ times the thickness. If it broke
right off it needs to be beefier to avoid fatigue (failure from repeated,
variable loads) and have adequate stiffness.

For what it's worth.

Hugh Currin
Klamath Falls, OR

On Friday 08 March 2002 06:14 am, you wrote:
> Depending on from where came the material it is more possible that it
> was 3000 series material. I would say just go with thicker material may
> be 1/4" or 3/8" and done. Just remember for to get the same strength as
> steel you need 2.5 times the thickness. So weight equals out.
> Have fun.
> Sven Peter