Q: cryogenic tempering appropriate for my application?

Cryogenic tempering (perhaps not the universally accepted terminology) has
been recommended to me as an alternative to induction hardening and/or case
carburizing in a pin used in a large thrust bearing (about 3' in diameter).
The pins serve as "axles" to hold an array of 40 radially arranged tapered
rollers in their assigned places within a cage assy.
The pins are currently 4140 QT (120ksi yield) induction hardened or 8620
case carburized x .55" diameter x 4.5 long. They have acceptable wear life
and fatigue life but are expensive to make mainly because they need to be
ground after hardening. The 4140 parts have a surface hardness of about 55RC
the carburized parts can be a little higher. The parts are press fit into
the cage with a substantial interference fit. We hold the diameters to
+/-.0002" by grinding after hardening. If the parts would remain
dimensionally stable after cryogenic tempering we have the ability to
machine them to that tolerance without grinding in their unhardened state.
If I adopt the cryogenic process I will no longer have a surface hardened
part but that may be OK.
I have three questions:
1--Is this method suitable for producing a wear resistant surface when
subjected to rotary sliding contact in my "axle" application?
2--Is the pin likely to be significantly more brittle?
3--Are the parts likely to be dimensionally stable enough that we can
eliminate the grinding after hardening?
I have the opinion of engineers from another division of our company that
use the process in an application where the workpiece is subjected to heavy
impact (it's inside a rock crusher) that feel that it has extended the life
of their parts, but their application is different. I am looking for some
opinions from persons using this method in applications more similar to my
Jon Juhlin
Reply to
Jon Juhlin
Loading thread data ...

Site Timeline

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.