Re: Cryogenic Treatments

["Bailey, Doug" <DBailey@xxxxxxxxxxxxxxxxxxxx>]

Joel,

As a metallurgical engineer doing failure analysis for an aircraft engine
manufacturer I found the topic intriguing.  I left the Cryogenic Solutions
site laughing.  The Pinnacle Cryogenic site is much more interesting as it
does provide a few technical words.  I can spout a bunch of technical words
too without backing it up with technical data.  At least they say they can
support their data if someone was to inquire.  There are a couple things
Pinnacle says that I would have some questions about.

Yes, they would have to disassemble the engine as each metal alloy has
different coefficients of thermal expansion, the amount of dimensional
change resulting from a temperature change.  

Since the chain is carburized (a surface hardening and heat treatment
process) a cryo treatment will not really do much for you as there will be
very little to no austenite at the surface.  Also, depending on the
application and stresses, some austenite is desired or required.  I would
assume that the sprockets are surface hardened too.  Also, hardening
operations are done prior to final machining because some distortion occurs,
like getting your new finished rotor back slightly warped.  A hardening
treatment is not the fix for what ails you.  The best way to get extended
chain life is to keep it properly lubed and adjusted or look for chains and
sprockets that are designed better.    

Could this help?  Yes, in certain applications, but you need to know the
specifics about your component, what alloy is it, what type of hardening has
it seen, what is the microstructure, etc.  What are the design requirements
for it, if it is harder how will it wear and affect the mating component.
It may help if it is designed into the processing and manufacture of the
component.  

Would I do it?  No. 

Doug Bailey "Hound Dawg"
'00 Sprint ST
'97 HD FXDL



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