Operating temperature limit of rolling bearings

Working temperature of rolling bearings: Because bearings are used in many occasions and environments, in most cases, the working temperature of bearings is not a problem. But some application conditions will have extremely high speed or working temperature. At this time, special attention must be paid to the operating temperature not to exceed the limit temperature of the bearing. The minimum limit temperature is mainly based on the lubrication ability. The maximum limit temperature is usually limited by the material and/or lubricant, but it may also be limited by the accuracy requirements of the bearing equipment. These restrictions are described below. Bearing material restriction: When the temperature exceeds 12C, ordinary bearing steel that has undergone standard heat treatment cannot maintain a hardness of at least 58 HRC. The correct heat treatment process ensures the stable dimensions of Timken bearings. Ordinary Timken® tapered roller bearings and ball bearings can maintain stable dimensions at temperatures from -54°C to 12C, ordinary spherical roller bearings maintain stable dimensions at a temperature of up to 20C, and ordinary cylindrical roller bearings have the highest Maintain stable dimensions at 15C. These bearings can provide the following higher stability upon request. These indicators comply with DIN Standard 623. Stability index Maximum working temperature °C °FS0 150 302S1 200 392S2 250 482S3 300 572S4 350 662 Products with stable dimensions may still undergo dimensional changes due to microstructure deformation during operation. These deformations are mainly martensitic tempering and The retained austenite decomposes. The degree of change depends on the working temperature and the duration of the temperature, as well as the forming and heat treatment of the steel. When the temperature exceeds the limit in Table 19, special high-temperature steel is required. Please consult your Timken engineer for the available bearing models for non-standard heat-stable steel or high-temperature steel grade products. It lists the ball, bearing ring and roller materials recommended for use at various operating temperatures, as well as the recommended chemical composition, hardness and dimensional stability. Operating temperature affects the thickness of the lubricating oil film and the operating clearance, both of which will directly affect the service life of the bearing. Extremely high temperatures will thin the lubricating oil film, resulting in poor lubrication of the contact parts. The operating temperature also affects the performance of the cage, sealing ring and dust cover, which in turn affects the performance of the bearing. Table 21 shows the materials of these parts and their operating temperature ranges.