Although the bearings are called standard parts, there are many kinds of types, materials and configurations. Even the bearings of the same specification, there will be different models, such as open type, iron cover seal, rubber cover seal and so on. How can we choose the right bearing when we need it? First of all, we should consider the bearing size, and then we need to consider whether the performance of the selected bearing meets the use requirements. In this issue, we will focus on how to select the appropriate bearing according to the operating conditions.

1、 Load of bearing

The size, direction and nature of the load on the bearing are the main basis for selecting the bearing type.

1. When selecting the type of bearing according to the load, the roller bearing should be used to bear a larger load because of the linear contact between the main components, and the deformation after bearing is also small. The ball bearing is point contact, which is suitable for bearing light or medium load. Therefore, when the load is small, the ball bearing should be preferred.

2. When the bearing type is selected according to the direction of load, thrust bearing is generally selected for pure axial load. Thrust ball bearing can be used for smaller pure axial load, and thrust roller bearing can be used for larger pure axial load. For pure radial load, deep groove ball bearing, cylindrical roller bearing or needle roller bearing are generally selected. When the bearing bears radial load R and there is a small axial load a, deep groove ball bearing or angular contact ball bearing or tapered roller bearing with small contact angle can be selected; when the axial load is large, angular contact ball bearing or tapered roller bearing with larger contact angle can be selected, or the structure composed of radial bearing and thrust bearing can be selected to bear radial load respectively And axial load.

2、 Speed of bearing

In general speed, the speed has no effect on the type selection, only when the speed is higher, it will have a more significant impact. The limit speeds of various types and sizes of bearings are listed in the bearing samples. This limit speed refers to the maximum allowable speed when the load is not too large (P ≤ 0.1C, C is the basic rated dynamic load), the cooling condition is normal, and it is the maximum allowable speed of bearing with grade 0 tolerance. However, because the limit speed is mainly limited by the temperature rise during operation, the limit speed in the sample can not be considered as an absolutely insurmountable limit. If the working speed of the bearing exceeds the limit speed, the following fifth measure can be taken.

The following points can be determined according to the requirements of rotating speed for bearing:

1) Compared with roller bearing, ball bearing has higher limit speed, so ball bearing should be preferred in high speed;

2) Under the condition of the same inner diameter, the smaller the outer diameter is, the lighter and smaller the rolling element is, and the smaller the centrifugal inertia force added by the rolling element on the outer ring raceway during operation is smaller, so it is more suitable for working at higher speed. Therefore, in high speed, it is advisable to select ultra light, ultra light and light series bearings. Heavy and extra heavy series bearings are only used for low speed and heavy load. If one light series bearing is used and the bearing capacity cannot meet the requirements, wide series bearing or two light series bearings can be used together.

3) The material and structure of cage have great influence on bearing speed. Solid cages allow higher speeds than stamped cages.

4) The limit speed of thrust bearing is very low. When the working speed is high, if the axial load is not very large, angular contact ball bearing can be used to bear pure axial force.

5) If the working speed slightly exceeds the limit speed specified in the sample, the high-speed performance of the bearing can be improved by increasing the tolerance grade of the bearing, appropriately increasing the radial clearance of the bearing, selecting the circulating lubrication or oil mist lubrication, and strengthening the cooling of the circulating oil. If the working speed is more than the limit speed, special high-speed rolling bearing should be selected.