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.

On Friday, January 31, 2014 8:50:22 AM UTC-5, wrote:
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.

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

On Friday, January 31, 2014 5:50:22 AM UTC-8, wrote:

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)

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

Does the spinning work harden the metal?

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

Can it be annealed afterword?

Yes, or between operations in multistep spinning operations.

How thin a wall/ bottom can you make?

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.

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

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)

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.

Does the spinning work harden the metal?
Can it be annealed afterward?
How thin a wall/ bottom can you make?

--
jiw

On Monday, February 3, 2014 8:08:11 PM UTC-5, whit3rd wrote:
On Friday, January 31, 2014 5:50:22 AM UTC-8, wrote:



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)

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

OK why do you say Al is the right stuff? I realize that most of the radiation 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 thermal conductivity. If you calculate a time constant to get heat out of a cubic centimeter of material (at 300K) you get something like 1 second for Al and a bit less for copper (0.85 seconds) Basically the same.

Thanks for the rest of you anwer.

George h.

Does the spinning work harden the metal?



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



Can it be annealed afterword?



Yes, or between operations in multistep spinning operations.



How thin a wall/ bottom can you make?



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.

On Tuesday, February 4, 2014 1:20:09 AM UTC-5, James Waldby wrote:
On Fri, 31 Jan 2014 05:50:22 -0800, ggherold wrote:

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)
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.


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

George H.

Does the spinning work harden the metal?

Can it be annealed afterward?

How thin a wall/ bottom can you make?



--

jiw