Rolling Bearing Selection Points

1. Decide the type and configuration of bearings
Selection of bearing type and configuration is based on the conditions of use.
Whether the main force and direction acting on the bearing is only radial load or also thrust load, and in the case of thrust load whether it is only in one direction or in both directions, choose the bearing type accordingly. If necessary, also consider the use and configuration of multiple bearings.
For example, deep groove ball bearings, which are commonly used bearings, are bearings that are mainly subjected to radial loads and cannot withstand large thrust loads. If this is the case, select angular contact ball bearings that can withstand thrust loads, or consider combining them with thrust bearings.

2. Determine the size of the bearing
Generally, in mechanical design, the shaft diameter is determined first, and then the bearing size is determined on the basis of the inner diameter (= shaft diameter). Bearing size series are therefore standardized on the basis of the inner diameter reference. From these standardized products, bearings that meet the conditions of use are selected on the basis of permissible loads and permissible speeds.

There are 2 reasons for considering permissible loads and permissible speeds.
-Exceeding the permissible load can damage the bearing
-Exceeding the permissible speed can cause abnormal heating of the bearing

Either case is related to the life of the bearing, so it is important to always maintain the permissible values.
For example, if the permissible load of a “deep groove ball bearing” is insufficient, the type of bearing must be changed, e.g. to a “cylindrical roller bearing”.

3. Decide on the material and lubrication method according to the usage environment.
The following three points are determined according to the conditions of use.
-Whether or not there is a dust cap (sealing device).
-Material of inner and outer rings
-Lubricant

Conventional bearings do not have dust caps and are called “open type”. The dust cap prevents the lubricant from leaking out, and also prevents dust and moisture from penetrating inside.
The material and lubricant of the inner and outer rings are selected according to the conditions of use.
For dustproof and underwater use, dust caps and stainless steel are used.