Re: Machining / Lathe questions

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Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

I would assume that the annealing process requires heating to a fairly high
temp (red heat?) and then cooling slowly. I see some potential problems: 1)
heating it all the way through.. a decent sized steel ball is going to take
a lot of heat and some real time to get heated through and through.  You
might just wind up heating the surface up. 2) Oxidation during the cooling
phase. Probably putting it in some sort of inert (or non oxidizing)
atmosphere during the cooling process would be called for.   I've seen SS
and Ti foil in catalogs where one of the applications listed is "heat
treating".. maybe this is what it's for. You shove the object in a foil bag,
purge with nitrogen, seal it up and throw it in the annealing oven.  Maybe
you don't even need to purge, because the oxygen in the bag gets consumed
quickly, and is of limited quantity.

Maybe you could pull the red hot steel ball out of the oven and "air cool"
it in dry nitrogen or CO2 (Putting it in a bucket filled with CO2 gas, fed
at a slow rate from a bulk tank might be what you need..). It might be that
you could find some suitable high temperature resistant coating? What about
shoving it in a bucket of dry salt or sand to cool? There's still air, but
the salt would make the diffusion fairly slow.

You might try one of the metalworking newsgroups or FAQs.  Seems like this
would be a pretty standard thing for the red hot metal beating crowd.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, March 30, 2003 11:15 AM
Subject: Re: Machining / Lathe questions


 > Original poster: "Ed Phillips by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<evp-at-pacbell-dot-net>
 >
 > Speaking of balls and machining thereof, does anyone have a good
 > technique for annealing ball bearings?  My attempts here have ended up
 > very poorly, with flaking oxide on the outside and still hard!!!
 >
 > Ed
 >
 >