1. Outer diameter measurement method: Use tools such as a micrometer or outer diameter gauge to measure the outer diameter of the bearing. This method is often used for bearings with larger outer diameters and shorter lengths.

2. Inner diameter measurement method: Use tools such as twist fingers or vernier calipers to measure the inner diameter of the bearing. This method is often used for bearings with larger inner diameters. In addition, the measurement of the bearing hole can also be carried out by using the inner diameter gauge to check the reference size on the outer diameter micrometer. At the same time, the roundness and cylindricity of the bearing hole also need to be measured.

3. Wall thickness measurement method: Use tools such as a micrometer or outer diameter gauge to measure the wall thickness of the bearing, which is often used for thinner-walled bearings.

4. Vibration spectrum analysis method: By measuring the vibration acceleration, speed and displacement values of the bearing at different frequencies, the spectrum characteristics are analyzed to determine the operating status of the bearing. This method requires the use of high-precision vibration sensors and spectrum analyzers, which has higher accuracy but longer measurement time.

5. Impact pulse method: By measuring the impact pulse signal generated by the bearing during operation, and analyzing its pulse amplitude and pulse frequency characteristics, the degree of damage to the bearing can be judged. This method has the advantages of being fast and simple, but its accuracy is slightly lower than the vibration spectrum analysis method.

6. Temperature measurement method: By measuring the temperature of the bearing during operation and analyzing its temperature change trend, the operating status of the bearing can be judged. This method is simple and easy to implement, but for high-speed running bearings, the temperature changes are small and the accuracy is low.

  In addition, there are rotation test, noise test, friction test, life test and other methods to comprehensively evaluate the performance and status of the bearing. The rotation test checks the rotational stability of the bearing, the noise test checks the sound of the bearing when it is running, the friction test evaluates the friction of the bearing when it rotates, and the life test evaluates how long the bearing is used under specified conditions.