calculating required tonnage

[williedawg]

Not sure if this is the right forum for this question...if there's a better place, let me know.

For an aluminum "Z" extrusion, how does one calculate the required tonnage for a cut-off,
given the shear strength of the alloy and the cross-section.
We are assuming the best method is to lay the "Z" to some angle to minimize the material thickness.

And yes, we'd be cutting off all at once, no side-shear.

 

[rb1957]

it sounds to me like you're trying to shear the extrusion ... would Fsu*A provide a reaonable number ?

 

[drawoh]

williedawg,

This sounds like a question for the Manufacturing and Plant Engineering forum.

Can you shear an aluminium extrusion? Aluminium extrusions tend to be made from heat treated, brittle material.

If you are preparing to spend a couple of hundred thousand dollars on a new machine and process, you should contact a consultant who actually works on this stuff.

JHG

 

[williedawg]

Thanks for the replies.

rb1957, yes, that is what we're attempting to do....what are the terms in Fsu*A ?

drawoh, yes, aluminum extrusions can be sheared if the net shape is either completely surrounded with a minumum clearance, say .010 per side or less depending on the consistancy of the product dimensions/squareness....OR a suitable pressure pad that is very close to the profile is provided as the shear die cuts the extrusion off. In either case, the shear die should be the near same profile as the part. I envision this being done with a wire-EDM and having an lead-in opening that is tapered to allow easier part entry.
Quantities involved should justify tooling costs.

per your suggestion, I'll repost this to the Manufacturing and Plant Engineering forum.

 

[hydtools]

Why not just use a chop saw or a cutoff saw?

Ted

 

[williedawg]

Ted, customer doesn't want the resultant chips from saws.

BTW, how does one start a new thread and make reference to an old one ?

 

[ornerynorsk]

How much distortion can you live with, what alloy is it, and what are the cutoff lengths, in general. This is easy stuff with a punch press, unless you need zero distortion, which is then impossible. A general rule of thumb for extrusion shear tonnage in the tool & die world is 15 tons per sq inch. Vogel Tool is an expert in this field, try them.

 

[rb1957]

about 1/2 sq in ... about 8 tons ... 10 sounds good (can't have too many when you're trying to break something !)

to get a clean cut you'd need to support the lower faces (something like a W shape) and the "blade" should contact all the upper faces at the same time (something like a M shape).

 

[IRstuff]

Is there no issue of the rightmost face potatochipping because it's being sheared at an angle?

You can copy/paste the thread ID at the top of the page, the forum software will translate it accordingly:
(thread 404-236506 without the space after the d in thread.)

thread404-236506

Just ask people to post replies here


TTFN

FAQ731-376

 

[williedawg]

In reply to the distortion concerns.... if we surround the profile, I don't think any of the legs or center section will distort any more than the clearances built into the die. There'll be a slight burr, but that's anticipated.

Imagine a border .010 (for example) around the outside of the profile,...that would be the die opening and, the opening that will be in the "punch" as well.....maybe I didn't elaborate enough, but that's what I was trying to explain in the response to drawoh.

Years ago, we made some cut-off dies for pre-formed stainless steel material that was used for the tops of display cases and some were dies that made miter cut at the same time. The approach to the problem of distortion was similar to what we'd like to do with aluminum parts. The thing we didn't get into was how to figure tonnage for a cross-section. The cut-off for the SS parts was for a die built for someone else to run in their facility, so they were the ones doing the sizing of the die set and press tonnage.

Thanks again to all.

 

[argusengineering]

williedawg,

Go to this page:

http://www.accurpress.com/pbrakes.html#loadCalculator

They have a Tonnage Calculator Online. It looks like you'd need a 25 tons press for your job.

Good luck!


Tudor Agapescu

http://www.argusengineering.net

 

[itsmoked]

You're sure this stuff won't crack or splinter?

Keith Cress
kcress -

http://www.flaminsystems.com