Operating temperature limits for TIMKEN rolling bearings

Rolling bearing operating temperatures: Since bearings are used in a wide variety of applications and environments, the operating temperature of bearings is not an issue in most cases. However, some applications may have extremely high rotational speeds or operating temperatures. Special care must be taken to ensure that the operating temperature does not exceed the limiting temperature of the bearing. **Limit temperatures are mainly based on lubrication capacity, **Limit temperatures are usually limited by the material and/or lubricant, but may also be limited by the precision requirements of the equipment in which the bearing is used. These limits are described below.
Bearing Material Limitations: Standard heat treated common bearing steels will not maintain a hardness of at least 58 HRC at temperatures above 120°C. The bearing material limits are based on the material and/or lubricant used. The correct heat treatment process ensures that Timken bearings are dimensionally stable. Plain Timken® tapered roller bearings and ball bearings maintain stable external dimensions at temperatures from -54°C to 120°C, plain spherical roller bearings** at 200°C and plain cylindrical roller bearings** at 150°C. These bearings are available on request with the following limitations. These bearings can be supplied on request with even higher stability as follows. These specifications are in accordance with DIN standard 623.
Stability indicators **Operating temperature
°C °F
S0 150 302
S1 200 392
S2 250 482
S3 300 572
S4 350 662
Dimensionally stable products may still undergo dimensional changes during operation due to microstructural deformations, mainly martensitic tempering and residual austenite decomposition. The degree of change depends on the working temperature and its duration, as well as on the forming and heat treatment of the steel. Temperatures exceeding the limits in Table 19 require the use of special high-temperature steels. Consult your Timken engineer for optional bearing types in non-standard heat-stabilized or high-temperature steel grades. The recommended ball, ring and roller materials for various operating temperatures are listed in Table 19, along with recommended chemical composition, hardness and dimensional stability. Operating temperature affects lubricant film thickness and running clearance, both of which have a direct effect on bearing life. Extremely high temperatures can thin the lubricant film, resulting in poor lubrication in contact areas. Operating temperatures also affect the performance of cages, seals and dust caps, which in turn affects the performance of the bearing. The materials of these components and their operating temperature ranges are shown in Table 21.

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