High-speed bearings face the dual challenges of high-speed, high-load operation and the optimization of NVH (noise, vibration, and harshness) characteristics. Simultaneously, shaft currents within electric drive systems-particularly those operating on 800V high-voltage platforms-pose a risk of electrical corrosion caused by the breakdown of the lubricating oil film.
Hybrid ceramic ball bearings-featuring steel inner and outer rings combined with ceramic rolling elements-have emerged as a key solution to these challenges due to their superior wear resistance, low frictional loss, lower operating temperatures, extended grease life, high limiting speeds, and excellent insulation properties. High-speed cage designs, such as SKF's TN6 cage (capable of a speed factor of 1.8 million nDm), work in conjunction with lightweight ceramic balls to reduce stress and the risk of ball ejection. Insulation strategies to mitigate electrical corrosion primarily involve ceramic coatings, polymer coatings, and ceramic rolling elements; notably, hybrid ceramic bearings utilizing silicon nitride rolling elements effectively block current flow, thereby preventing failure due to electrical corrosion.
Cage materials have evolved from copper alloys and steel to engineering plastics (such as Nylon 66) and composite materials (such as PEEK and graphene-modified materials). The use of Nylon 66 helps push the boundaries of bearing limiting speeds, while composite materials like PEEK and graphene-modified variants significantly enhance high-temperature resistance and mechanical strength [7].
