The main purpose of bearing lubrication is to use lubricant to form an isolating lubricating oil film on the friction surface between the ring, rolling element and cage to reduce the friction of the bearing, prevent sintering, and prolong the service life of the bearing. In addition, the lubricant can also play a role in preventing bearing rust, reducing vibration noise, cooling, and preventing the intrusion of external foreign matter.
- Grease lubrication
Grease lubrication is the most commonly used lubrication method for bearings because of its convenient use and simple maintenance.
The most commonly used lubricating grease for rolling bearings is lithium-based grease with mineral oil as the base oil. This grease has good adhesion and has good lubricating effect in a large temperature range and speed range. The applicable range is -30℃～+110℃. For high-speed precision spindle bearings and rolling screw support bearings, compound barium-based grease or calcium-based grease with synthetic double-grease lubricating oil as the base oil can also be used, and the consistency should be No. 2.
The amount of grease filling for high-speed precision bearings is recommended to be 15% to 20% of the internal space of the bearing. For the amount of grease filling for spindle bearings, refer to the attached page? , Refer to the attached page for the grease filling amount of the ball screw support bearing?
Grease-lubricated bearings must be run-in at the beginning of work. After running-in, excess grease is forced into the bearing raceway, so that the grease in the bearing is evenly distributed. And it can ensure the lowest heat balance temperature when the bearing is working normally.
The normal running-in procedure is to gradually increase the speed in stages, and each stage must wait for the temperature of the bearing to stabilize before moving to the next stage. If there are too many stages or the limit speed of the bearing is high, the running-in time will be longer.
The running-in can start at 20% to 25% of the limit speed, and increase the speed when the stable temperature is reached, until the limit speed of the bearing is reached and the temperature is stable. In particular, it should be noted that during the running-in process, the temperature of the bearing should be monitored at any time. If possible, the temperature of the outer ring of the bearing can be directly monitored. When the temperature exceeds 60°C, stop the machine, and when the temperature drops by about 10°C, restart it at the same speed until the running-in ends.
Grease should be replenished and replaced within a certain period of time. When adding grease, it should be noted that greases of different types and specifications cannot be mixed, otherwise the performance of the grease will be reduced. In addition, the original grease should be cleaned when replacing the grease. - Oil lubrication
When grease lubrication cannot meet the high-speed performance requirements of the machine tool, oil lubrication can be used.
The most commonly used oil lubrication methods for precision machine tool spindle bearings include oil mist lubrication, oil-air lubrication, and oil spray lubrication.