Metal spinning

Hi all, This is a simple metal spinning question that I was asked to bring here. (I know nothing about metal spinning.)
I'd like to make some little radiation shields for use at 77K (liquid nitrogen) So cylindrical type cups.. maybe 2" diameter and 3-4" long. I've only heard about spinning aluminum, but can you also spin other metals something like TeCu (tellurium copper)
Does the spinning work harden the metal? Can it be annealed afterword? How thin a wall/ bottom can you make?
George H.
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On Friday, January 31, 2014 8:50:22 AM UTC-5, snipped-for-privacy@gmail.com wrote:

Hi George,
Yes, it will work harden like crazy. Depends on material.
Copper spins nicely. Tellurium I don't know. The spun material needs ductility to start with. Copper must be annealed before, after, and sometimes during, the spinning process.
Thickness of wall is the thickness you start with, minus the amount you stretch it to the form. Not all that easy to control. Too thin and it will tear. Too thick and it will need great force to shape.
Have you considered using a simple hemispherical male die pressed into a block of contained urethane for these instead? Limited in its draw depth, but might be a viable alternative to spinning them.
Good luck, let us know how it turns out.
--
PaulS

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On Friday, January 31, 2014 5:50:22 AM UTC-8, snipped-for-privacy@gmail.com wrote:

Yes, of course you can spin other metals; for a heatshield, though, Al is the right stuff.

Yes; that's one good reason to do it. Gongs and cymbals for instance, are almost always spun.

Yes, or between operations in multistep spinning operations.

Only limit is if the metal tears (and polished tools and/or heavy greases are recommended to minimize this). It's recommended to spin alternately from center out and from rim in, to get a uniform thickness result.
If you care for a less dynamic approach, you can also consider cold-drawing of aluminum; machine an internal die and press a metal sheet against a block of rubber (urethane? neoprene? silicone?). It'll take several steps and annealing between draws.
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On Monday, February 3, 2014 8:08:11 PM UTC-5, whit3rd wrote:

itrogen)

eard about spinning aluminum, but can you also spin other metals something like TeCu (tellurium copper)

the right stuff.
OK why do you say Al is the right stuff? I realize that most of the radiat ion sheilds I've seen are Al. But what is wrong with nickel plated copper? Copper has a little more heat capacity (per volume), but also a greater the rmal conductivity. If you calculate a time constant to get heat out of a c ubic centimeter of material (at 300K) you get something like 1 second for A l and a bit less for copper (0.85 seconds) Basically the same.
Thanks for the rest of you anwer.
George h.

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On Fri, 31 Jan 2014 05:50:22 -0800, ggherold wrote:

As mentioned in P. Schiller's answer, copper spins ok, if annealed whenever necessary. I don't know the answers to your other questions, but want to suggest that if you can obtain your material in pipe form (or if you can make a pipe), spinning just the base of the cup probably minimizes the distance that material needs to move. Ie, if you start with a flat 6" disk of metal and spin a cup of 2" diameter and 4" height, some of the metal has to move more than 4 inches. If you instead start with 4.5" of 2" pipe none of the metal has to move more than an inch.

--
jiw

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On Tuesday, February 4, 2014 1:20:09 AM UTC-5, James Waldby wrote:

Interesting! Thanks. I didn't know you could start with a cylinder. (Makes total sense though.)
George H.

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