Hybrid cylindrical roller bearings (designation suffix HC5) are available in the N 10 series and can be supplied on request in the NN 30 series. They have rings made of bearing steel and rollers made of bearing grade silicon nitride (ceramic). As ceramic rollers are lighter and have a higher modulus of elasticity and lower coefficient of thermal expansion than steel rollers, hybrid bearings can provide the following advantages:
- higher degree of rigidity
- higher speed capability
- reduced centrifugal and inertial forces within the bearing
- minimized stress at the outer ring rolling contacts at high speeds
- reduced frictional heat
- less energy consumption
- extended bearing and grease service life
- less prone to skid smearing damage and cage damage when subjected to frequent rapid starts and stops
- less sensitive to temperature differences within the bearing
- more accurate preload control
For additional information about silicon nitride, refer to Materials for bearing rings and rolling elements.
In order to maximize the performance of a hybrid bearing, SKF recommends using hybrid single row bearings with an outer ring centred window-type PEEK cage (designation suffix PHA or TNHA). These bearings, depending on the cage design, can attain speeds up to A = 2 200 000 mm/min, when under light load and lubricated with an oil-air system, (diagram 1). They can attain speeds up to A = 1 800 000 mm/min, when grease lubricated (diagram 2). As an option to further improve lubricant flow, bearings in the N 10 series with a lubrication hole in the outer ring can be supplied on request.