Bearing monitoring can reflect the changes of precision bearings or any changes under operating conditions can be used as measurement values u200bu200bfor bearing monitoring. They can be force, vibration, temperature, driving force, etc. In the process of bearing monitoring, it is not important to always ensure that the absolute value of the measured value is not important. The possible changes in the monitored value are more important. For example, an absolute temperature of 40 °C will not damage rolling bearings. If this steady-state temperature rises from 35 °C to 40 °C during deceleration in a short period of time, then this may be a clear sign that the bearing is beginning to be damaged. When selecting the monitoring method, it should be considered whether the damage of the bearing at low or medium speed gradually increases after a long period of time. In these cases, it makes sense to conduct regular monitoring. At high and extremely high speeds, natural failures should also be included in the risk assessment. Only in this way can bearing damage be reduced under continuous monitoring. In the past, bearing monitoring was only used to ensure the quality of newly processed or repaired spindles. For example, shortening of downtime or natural frequency measurement are all considered. In these two processes, problems caused by preloading will be quickly and accurately detected. Measurements of temperature, vibration velocity, and acceleration are common methods for quality assurance. These methods can only be used for comparable processes, such as the measurement of reduced downtime. Temperature monitoring In many cases, temperature is very important to the running performance of the bearing. Generally speaking, the aging or failure of grease lubricated bearings can be found in time. The change of preload leads to the failure of bearing floating, which has a relatively stable correlation with temperature changes. Generally speaking, the temperature is measured on a stationary ferrule, usually the outer ring. The temperature change within a certain period of time is used as the basis for evaluation. The following is a guide for reliable temperature measurement methods: Measure as close to the bearing as possible. Continuously measure as much as possible. Avoid measuring force to cause bearing deformation. The normal bearing temperature change mode is steady. However, if the service life of the grease is exceeded, the temperature change will be very unstable, showing up and down changes. When the bearing performance begins to decrease, corresponding measures must be taken.