Cold forming memory metal?

Question

I have some 'Flexon' memory metal glasses frames that need adjustment where they rest on the ear. All I know is that this is some kind of Ti alloy that is in the superelastic phase at room temperature. This means that it always wants to return to the original shape once the bending force is removed.

What little information I can find on the web suggest that these can be permanently bent into shape but so far I've had no luck at all. I'm worried that if I just keep increasing the force then it will snap before it permanently bends. Is this likely to happen?

Other information suggests annealing the metal at 400-500 deg Celsius, but that will mean destroying the plastic coating where it wraps around the ear.

Mike

anorton · Accepted Answer

I have had these glasses before. If you bend them beyond a certain point the relaxed shape will change. Don't worry, they are nearly impossibly to snap. It is best if you do not try to bend them in a small area; try to bend a large part of the earpiece. I would guess that you have to bend it to a radius of 10 or 20 times the width before it takes permanent set.

That said, it is really hard to get them adjusted just right.

Ecnerwal · Answer

...You're supposed to adjust them by bending the non-memory-metal parts, which bend quite cooperatively. Put a few decades on the things myself. Broke a LOT less than the heavy metal frames before them, which broke a lot less than the plastic frames they started me out on as a kid...

Bill · Answer

mean destroying the plastic coating where it wraps around the ear.

I broke one set, I was just twirling it in my hand while thinking, and the temple snapped in half - but it lasted longer than earlier ones - as said above, bend beyond the elastic limit and it will stay that way

Cold forming memory metal?

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