From: gmk@falstaff.MAE.CWRU.EDU (Geoff Kotzar)
Subject: Re: Teflon-based lubes for sizing?
Organization: /etc/organization

In article <92315.110030U53734@uicvm.uic.edu> U53734%uicvm.uic.edu@OHSTVMA.ACS.OHIO-STATE.EDU (Wesley Bielinski) writes:
#I understand that I full length carbide die for bottle-neck cases would
#be cost prohibitive, but why can't they bond teflon to the inside of a
#normal die (they do it to pans) so that it's permanently lubed?
#
#Wesley J. Bielinski                    | "I love my country,
#SGT, USAR       U53734@uicvm.uic.edu   |   it's CLINTON I fear!"
#12th Special Forces Group (Airborne)   |     Support RKBA


Teflon will cold flow under shearing loads. When total hips first came out
the first combination of materials tried was stainless steel on teflon.
Teflon ws chosen because of the low coefficient of friction. They were
catastrophies requiring early revision, very early revision. Teflon was
replaced by ultra-high molecular weight polyethylene. Which, while it is
an acceptable substitute for total joint applications, would not stand up
to the demands of cold forming -swaging- brass cases. Also, for any polymer
the least little bit of grit could destroy the coating requiring that cases
be immaculately clean.

The best bet as far as coatings go would be the hardest possible. NASA was
working on depositing crystaline carbon, in the form of diamond not graphite,
onto various substrates. This was a while ago and I never heard the outcome.


geoff kotzar