Sheet Metal Bending 3

[sbozy25]

Ok, so I am having a brain fart. I used to have a handy chart for bending sheet metal. It had a series of formulas and factors for different kinds of materials and different bends to show how much the material would thin out at the bend section. I have tried googling many terms to find some sort of diagram or table with no luck. I even dug through all my old text books from college to find it, also with no luck.

Does anyone know where I might find something that will help me? Oh, and the machinery handbook is not an option as my company does not allow it on the premises.

I know this is kind of an easy question, so please spare me the arrogant snide little comments that ususlay come with them. I already feel dumb for having to ask, I don't need others to tell me as well.

Thank You...

 

[rb1957]

in my business, typical bend radii for forming sheet metal is 3t. works for 2024T3 ... maybe a little more for 7075T6 (5t?).

it is easier to bend in O-condition if you're going to heat-treat back to structural properties later.

what sort of mateials are you mostly interested in ?

what sort of snide comments were you expecting ?
arh, forget that ... you've probably been reading some of the other threads !!

 

[sbozy25]

Well, this project I am working on is requesting 17-7PH stainless, it has a 180° bend and I want to make sure the material will not stretch to much and cause a thin condition. It will be formed in an annealed state, then hardened at a later manufacturing stage in fixtures.

Yes, in many of the other posts I read, there is always someone whoe feels like they are superior to everyone else, and they make it a point to make the questioner look stupid. I don't think that it is needed...

 

[strokersix]

Out of curiosity, why is Machinery's Handbook not allowed?

 

[mechengdude]

I've gotta hear why the MH isn't allowed too!!

 

[dvd]

It's always good to check with your sheet metal fabricator to see what bend radius they can provide, in addition to knowing what your requirements are. You can spend lots of time developing a blank and showing nice bends on your part that cause grief for the fabricator.

 

[fcsuper]

Does you company have a similar prohibition against Marc's?

I can see why someone may not want to allow final design to be based on MH data (since is it neither a standard nor a primary source for data), but why the actual prohibition? (You had to know questions like this would come up! )

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[sbozy25]

We are the fabricator of this part. I have been asked to quote it to a new customer, and they are design responsible. I think they have some issues and I am trying to make a list, so when I talk to the designer, I can tell him what his problems are.


MH is not allowed because it is viewed as an inacurate, un-manufacturable set of data. Most of the reccomended values in the book are impossible for suppliers to meet. So to keep problems from occuring, we ahve outlawed the use of the book... They seriously send someone around to collece every copy in the company and got rid of them.

 

[ewh]

I may have been willing to take mine home, but to have a company confiscate it would send my resume out on the streets pronto!

 

[sbozy25]

The company were the ones who bought them in the first place. It is actually a great company to work for, great pay, great benifits, just some weird practices from time to time...

 

[ewh]

Their property, different situation...
It does seem strange though that they would remove them without supplying allowable standards to replace them.

 

[rb1957]

if you're a small outfit, you could always ask the guy who does it ...

 

[hydtools]

Is this helpful?

http://www.sheetmetaldesign.com/WhitePapers/BendAllowance/SheetMetal-BendAllowance.pdf

Ted

 

[fcsuper]

Sorry for just asking about the policy. A star for ewh's multiple good observations though.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[sbozy25]

No you are fine... I kind of figured it would draw some questions. I was confused about it as well, but that is perhaps because I am the only degreed engineer. Everyone else is an engineer by experience, so they don't think the same way as I do. I see the book as a good reference tool to get me started, they saw it as the book of the devil... Oh well. that's the way it is....

No, that link doesn't help. But thank you... I ended up finding the paper I was looking for when i was home at lunch. It was burried in my files, it shows how much the material will expand and contract depending on what the metal is, the thickness, and the type of bend.

Thank you all for you attempt at help though.

 

[monkeydog]

You wouldn't happen to have a MH at home too?
;-)

 

[jistre]

Perhaps SMACNA or ASHRAE have some insights into the matter due to all of the ductwork those organizations' members deal with.

Now, back to this MH thing. The recent editions of the book are 2600-2700 pages long. If you look at any inaccuracies included in it on a mistake per page basis, I wonder how it compares with "acceptable" reference materials?

Sorry, I find the MH angle fascinating, as I'm sure several others do.

 

[KENAT]

So while I wouldn't go so far as to ban it, there are 'issues' with some data in machineries beyond simple typo errors etc.

A lot of it as suggested above is more in how it's used than in the book itself.

That said, it's on my Christmas list for this year!

sbozy, don't suppose you fancy scanning that page and sticking it on here, maybe use the Engineering.com link. It's something that has come up here before.

KENAT, probably the least qualified checker you'll ever meet...

 

[CorBlimeyLimey]

Fascinating??? I find it incomprehensibly stupid that a company could be so shortsighted and belligerent as to ban what, in the engineering world, is second only to The Hitchhikers Guide.

 

[MikeHalloran]

That's odd. Most of the self- taught engineers I know trust MH because they know they can't do better from first principles... and because they know it's usually close enough for government work.

I can deal with arrogance, and I can deal with ignorance, but that particular combination is very dangerous, because the one flaw makes it impossible to correct the other.






Mike Halloran
Pembroke Pines, FL, USA