Bearing combo prolongs life

Industry’s demands for increased performance and service life can be met, according to SKF, by hybrid bearings which combine silicon nitride balls with steel inner and outer rings.

Test programme results indicate that hybrid bearings lasted up to six times longer than their all steel equivalents and there was no significant difference in grease life.

Silicon nitride balls have two main advantages. For a given size, they have only 40% of the mass of steel balls. Also, their modulus of elasticity is 50% higher which means that ceramic balls are much stiffer. The material can also be regarded as an insulator due to its high resistivity. Electrical conduction through a bearing leads to surface damage caused by washboarding and false brinelling.

Wear performance test showed that steel bearings exhibited an increase in clearance and wear of the inner ring after 100h of some 58um, while for the hybrid bearing it was 5um.

Three main styles of hybrid ceramic bearing are available, high speed, express and optimised, to meet the demands for increased operating speed, greater stiffness and higher operating temperatures. A 719CD series optimised hybrid bearing offers 80% higher radial stiffness, 60% higher axial stiffness and can run at speeds some 25% higher than an all-steel high speed bearing.

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