Effect of Particulate Contamination in Grease-Lubricated Hybrid Rolling Bearings

Tlre preserrce oflrarrl corrtarnir~rrrIt.s in lubricated rolling bearing.~ is (I rrrrijor cr1~1.s~ of /~rel~rrrti~re failure, for exarnple by fatigue or I J ~ rrbr(r.sive rt~erlr of rolling el en rent.^, races or cages. However; tlre brtrotluctiorr of rtruclr Irorcler ceranzic (u.sually silicon nitride) balls or r01ler.s rurrrrirrg rlgnirzst steel races, in tlre lzybrid bearing concept, is likely to clrarrge the inreracrior~.s of hard particulate co~rtorrrirrarrt.s wit11 tlre bearing corirporrents. TIre pefir~ncr~rce of crll-steel and hybrid rollirzg bearings was irrl)estigated irr tlre preserrce of two well-dejinerl particulate contcrr~rirrc~~rt.s. Experi~ne~rts were carried out with grease-lubricated tlrrrr,st berrrirrgs, contaminated with titorlia (rrnatase) and silica (quartz) particles. A .sigrIificur~r herreficial effect was observed in tlre hybrid beori~rgs irr tlre presence offine (<5 pm) arratase particles, as lower crrge werrr N I I ~ running temperature were recorded. Tlris ir~rproverrrerrt wt1.s nssocioted with the formation of thin and relatively soft titr~rrio fi11n.s on the silicon nitride hall surfaces. Irr tlre (111-steel berlrings, silica 17article.s caused severe wear of tlre bal1.s C I I I ( / crrge, whereas in /Ire hybrid becrring no wear could be detecterl on the l~all.s, nrrri cage wear was sigr~ificantly lower tlrrrrr for tlre (111-steel 6ecrrir1g. T11e wear losses of the steel racewcrys were si~itilur in hot11 cases.