Bearing speed is one of the most important factors affecting bearing temperature rise.The maximum allowable speed of the bearing, that is, the limit speed, decreases with the increase of the bearing diameter series and width series.

The ultimate speed is related to bearing type, size, load, lubrication, precision, clearance, cage and cooling conditions.However, the most important factor is the allowable operating temperature of the lubricant or bearing material.

The speed of the bearing is mainly limited by the temperature rise caused by the friction heating inside the bearing. When the speed exceeds a certain limit, the bearing will not continue to rotate because of burns and so on.

The limit speed of bearings refers to the limit value that does not produce friction heating that causes burns and can be continuously rotated.Therefore, the ultimate speed of the bearing depends on the type, size and accuracy of the bearing, as well as the lubrication mode, the quality and quantity of lubricant, the material and type of the cage, load conditions and other factors.

The ultimate speed of each type of bearing with grease lubrication and oil lubrication (oil bath lubrication) is shown in the bearing size table respectively. The value represents the standard design bearing under general load conditions (C/P>13, a/Fr

Insufficient or excessive lubrication; lubricant.Containing impurities, excessive load, bearing ring damage, insufficient clearance, and high friction caused by oil seals will lead to the normal use of bearings, but improper rapid operation will also lead to bearing damage.

In addition, lubricants depending on their type and brand may be superior to other properties but not suitable for high speed rotation.

Bearing in high speed rotation, especially when the speed is close to or beyond the limit speed recorded in the size table, the main attention should be paid to the following matters:

1. Use precision bearings;

2. Analyze the internal clearance of the bearing (considering the reduction of the internal clearance of the bearing caused by temperature rise);

3, analysis of the cage type of material (for high-speed rotation, suitable for the use of copper alloy or phenolic resin cutting cage.There are also synthetic resin shaped retainers for high speed rotation);

4. Analysis of lubrication mode (using cycle lubrication, jet lubrication, oil mist lubrication and oil and gas lubrication suitable for high-speed rotation).

From the requirements of working speed on bearings, the following points can be determined:

1) Ball bearings have higher limit speed and rotation accuracy than roller bearings, so ball bearings should be preferentially selected at high speed.

2) Under the condition of the same inner diameter, the smaller the outer diameter, the smaller the rolling body, the smaller the centrifugal inertia force of the rolling body on the foreign raceway during operation, so it is suitable for working at a higher speed.Therefore, at high speed, it is advisable to choose bearings with smaller outer diameters in the same diameter series.If a bearing with a smaller diameter and the bearing capacity is not up to the requirements, the same bearing can be installed again, or consider using a wide series of bearings.

3) The material and structure of the cage have a great influence on the bearing speed.Solid cages allow higher rotational speeds than ram cages and bronze solid cages allow higher rotational speeds.