SKF® hybrid bearings with silicon nitride rolling elements and steel rings are designed to provide insulation against stray currents in large variable speed electric motors to help eliminate electric arc bearing damage, which can result in premature bearing failure. The ceramic rolling elements are said to make the bearings lighter, harder and more durable alternatives to their all-steel counterparts. The silicon nitride balls are 40-percent less dense than those made of steel, reducing centrifugal force and friction to promote faster, cooler running and longer service and lubricant life. They are harder than steel, the supplier says, for enhanced wear resistance against hard particles, contaminants and vibration. They are also highly inelastic, to provide increased bearing stiffness and reduced deflection under load.
Silicon nitride balls are said to experience less wear and provide better bearing service life under poor lubrication conditions compared with steel bearings. Standard types include hybrid single row deep groove ball bearings with bore diameters from 5 mm to 110 mm; sealed and greased-for-intended-life ball bearings protected by steel-reinforced synthetic rubber seals and filled with premium lubricant; and open, basic design bearings available without seals. Cages are glass fiber-reinforced polyamide or pressed steel, depending on bore size. Customized hybrid bearing versions can be developed per application requirements. SKF USA Inc., www.skfusa.com