motionper wrote:it's a knife and fork rod set up,no place to put bearing shells, have been thinking about trying ceramic rollers has anyone done this before???
Similar metals are rarely run together as hard working long life bearing surfaces as there are likely to be compatibility problems if they ever come in contact.
Tricks like carburizing, nitriding or plating, magnificent geometry and surface finishes and bountiful lubrication with EP or anti-war additives are needed to make steel on steel last.
Steel on steel in roller bearings (rollers, crankpin, races) works reasonably well because the parts' design and manufacturing is so highly developed.
Hybrid ceramic ball and roller bearings have vastly improved tribological performance in part simply because the ceramic rollers are not steel.
If your crankpin and roller problems start with rollers skidding causing surface damage then I'd expect ceramic rollers to work 10X better.
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The modulus of elasticity (stiffness) of silicon nitride commonly used in ceramic balls and rollers is about 50% higher than steel.
The density is much lower than steel so the balls/rollers are about 50% lighter.
See Fig 9 here -
http://www.schaeffler.com/remotemedien/ ... _us_en.pdf
High stiffness means the balls do not conform to the steel race as well, and gently as steel balls. They sink in Kind of like riding a 10 speed bike with skinny tires on the beach. Thus with equal load and geometry the contact and Hertzian stresses are higher using HC balls or rollers. Hitting or pressing an HC bearing will dent the races before the balls are dented. Despite the higher stress Bearing manufacturers can quote greatly improved life with HC bearings operating within their rated capacity because the surface tribology is SO much better.
If your crankpin/roller problems are strictly load related then I think the stiffer HC rollers will make it worse.
The light weight can really help if oscillating speed variation, so if roller inertia is causing roller skidding and eventual surface damage ceramic rollers can help a lot there too.
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Some are concerned that being a ceramic the balls/rollers are brittle and will fracture or crush under impact.
I worked at a precision machine tool spindle company for several years. Lots of the spindles used HC bearings, and some would fail in testing, but invariably the steel races would be burnt and smeared junk but the balls would be perfect, so excellent used HC balls were available. The guys in the shop gave me some, boasting all their experiments whacking a loose ball with a big steel hammer resulted in a dented hammer, but never a damaged ball. I have a dented hammer and deeply dented steel plate having tried that experiment myself. So I'm not too worried about name brand ceramic balls and rollers being brittle.