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Need information on metal strap with no (very little) work hardening.

1. How sharp a bend radius are we talking here?
2. Does it need to be metal, and if so why?
3. Flexure designs in metal tend to be low strain. Applications requiring high strain are often include hinges or varying designs.
 
Maybe I'm missing something here, but there are conventional hinges that fold flat. With a sufficiently tight hingepin and straps of the same gauge as the hinge, it could be open to 180 or closed at 0. What am I missing?
 
Phosphorus bronze is used for flat beam springs. It has a good flexibility within it's range of flexture. Any material, including spring materials has a flexure limit and as long as it is designed within these limits will last a long time.

BTW, Elginloy and MP35N, last price I saw for that material is above $50 lb. We have several springs designs that uses MP35N in the .005" thickness by 1" wide strips. The leaf spring is bent with a 90° bend with a fairly large radius at the bend. The spring goes to flat to just beyond flat in the opposite direction when compressed, and when returned, keeps its shape. It's fairly stout when you get it flatten, too.
 
1. How sharp a bend radius are we talking here?
2. Does it need to be metal, and if so why?
3. Flexure designs in metal tend to be low strain. Applications requiring high strain are often include hinges or varying designs.
As mentioned above the design needs a very flexible and yielding (probably) metal strap that could be bent into postion and then be expected to hold that position with modest resistance to further bending or straightening much like the metal tab works on a manilla envelope. So, it behaves somewhat like the gooseneck on a good work light but can be bent more shaprly like flat and then unbent into any general shape whether that is straight, c-shaped etc.
Maybe I'm missing something here, but there are conventional hinges that fold flat. With a sufficiently tight hingepin and straps of the same gauge as the hinge, it could be open to 180 or closed at 0. What am I missing?
See above.
Phosphorus bronze is used for flat beam springs. It has a good flexibility within it's range of flexture. Any material, including spring materials has a flexure limit and as long as it is designed within these limits will last a long time.

BTW, Elginloy and MP35N, last price I saw for that material is above $50 lb. We have several springs designs that uses MP35N in the .005" thickness by 1" wide strips. The leaf spring is bent with a 90° bend with a fairly large radius at the bend. The spring goes to flat to just beyond flat in the opposite direction when compressed, and when returned, keeps its shape. It's fairly stout when you get it flatten, too.
Shape memory is not what is desired. Actually the opposite. And memory or lack thereof were a bit cloudy in the online blurbs I read about those materials. So 1/4" lead bar stock generally has the flexibility and shape holding qualities desired. Better would be a material that would have better holding with less weight.

I do like finally hearing some "boots-on-the-ground" experience with MPN35N. But I do not think it will do what I need. The expense would not, by itself, be a deterrent.

Thanks to all above. And sorry forma somewhat slow response as I have had a busy day machining 99.99% pure silver---a new and not nearly as unpleasant a task as expected.

Denis
 
It sounds a bit like you want a high friction hinge, or a design modification with a pocket for something to fit into so the bend doesn't need to be quite so sharp.

Manilla folders don't quite bend sharp, and they don't survive as high a cycle count as you might expect.
 
It sounds a bit like you want a high friction hinge, or a design modification with a pocket for something to fit into so the bend doesn't need to be quite so sharp.

Manilla folders don't quite bend sharp, and they don't survive as high a cycle count as you might expect.
That is why I am looking for something better. It was simply an example for the bending and holding function as that concept has not been generally appreciated by respondents.

Denis
 
That is why I am looking for something better. It was simply an example for the bending and holding function as that concept has not been generally appreciated by respondents.
If it weren't for having to anneal it all the time, copper really does do what you describe.

You haven't described the use so ... if it is once a month, major operation by trained guys then annealing is no big deal. If it's three times an hour like opening the refrigerator by unskilled people then no.
 
If it weren't for having to anneal it all the time, copper really does do what you describe.

You haven't described the use so ... if it is once a month, major operation by trained guys then annealing is no big deal. If it's three times an hour like opening the refrigerator by unskilled people then no.
Potential consumer product. I've descrbed use in general enough terms, I think. Specific use description is (wisely) not allowed by the person, my son, requesting consultation.

Denis
 
That is why I am looking for something better. It was simply an example for the bending and holding function as that concept has not been generally appreciated by respondents.

Denis

Hinges and holding.
Sounds like you need a hinge designed with appropriate plate geometry to snap into place.
These are done by having curved plates which create a spring action when articulated
That is the hinge axis is curved and less so when “closed”.
Done properly these have a very snappy feel to them as they impart, overcome and relieve the imposed stress in articulating the hinge.

I’d go with the plastic re-post #16 by Erich.
Is your component 1”x12” folding across that ribbon?
What angle does the component have to work through?
Thickness and attachment constraints?

“My adult son and I are brainstorming a device that would require a strap of metal”

Does this component need strength when open or at all angles of not closed or is just “holding” when closed the only job?
What axis of load- how much?
How much “holding” force needed?
 
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