How to find a suitable high temperature resistant bearings?

1. Heat treatment dimensional stability temperature of bearing steel

For ordinary bearing steel, there is a stable temperature for heat treatment. Below this temperature, the bearing remains dimensionally stable, and the hardness of the bearing steel material also meets the requirements for use.

Generally, the stable temperature of heat treatment for bearings is 150 °C.

2. Bearing cage temperature range

Usually steel or brass cages can withstand a relatively large temperature range. The heat-resistant temperature of steel cages can reach 300°C, and brass cages can reach 250°C, but for nylon cages, they can generally withstand -40 to +120°C. temperature range.

3.Temperature range of seals

For enclosed bearings, metal dust caps do not require special consideration of the temperature range. For rubber material seals, this needs to be considered. The working temperature range of nitrile rubber (NBR) is -40～+120℃, it can work stably within 100℃, and it can work at 120℃ for a short time; When working at 230 ℃.

4. Permissible temperature range of bearing grease

Temperature is one of the most important factors affecting lubrication life. Grease base oil viscosity decreases with increasing temperature. Based on grease life calculated at 70°C, the life will be reduced by half for every 15°C increase in operating temperature. The allowable working temperature of the bearing for the motor should be the intersection (the narrowest range) of the allowable temperature range of the various components of the bearing, and only within this range can the safe operation of the bearing be guaranteed.

Therefore, whether the bearing can operate in a high temperature environment mainly depends on the choice of lubricant, followed by the bearing sealing material (only for closed bearings) and the cage, and finally the bearing steel. In practice, the temperature generally measured in the application is the temperature near the outer ring of the bearing, and the difference between different measurement methods and positions can be up to 15 °C. Generally, the heat dissipation condition of the bearing seat is better than that of the shaft, so the temperature of the inner ring and rolling elements is 5~10 °C higher than that of the outer ring. Therefore, when the test position is outside the bearing outer ring, if the measured temperature is 95°C, the hottest spot temperature of the inner ring may reach 120°C. This temperature has reached the stable heat-resistant temperature of nylon cage, bearing steel and grease, so it is necessary to choose bearing materials with better heat resistance, such as stainless steel bearings or ceramic bearings.