Bearings are an indispensable part of mechanical equipment. Reliable operation of bearings in electric spindles is even more important, which directly affects the performance indicators of machine tools. In addition to bearing performance affected by its own material, the choice of lubrication and cooling methods is also very important. To realize high-speed cutting of machine tools, first of all, the shaft speed must be high, and high speed requires stable bearing performance. Lubrication is an important factor to ensure bearing performance. Using bearing oil and gas lubrication, the bearing can be well lubricated, the electric spindle runs more stably, and the good running index is obtained.

Among the factors that affect the speed and performance of the electric spindle, the thermal deformation is related to lubrication. The internal heat source of the electric spindle comes from two aspects: the built-in motor and the heating of the spindle bearing.

The heating of the spindle bearing can be solved by using oil-air lubrication. The bearing size of the electric spindle is not too big and does not need a lot of lubricating oil for lubrication. If a large amount of lubricating oil is used for intrusive lubrication with traditional lubrication methods, the method is not advisable, mainly because it cannot provide good lubrication and will waste a lot of lubricating oil. The lubricating oil in the continuous circulation process will also cause the oil temperature to rise due to the friction between the oil molecules, which is not conducive to the operation of the electric spindle. Therefore, bearing oil-air lubrication is selected. This micro-lubrication method can reduce the supply of lubricating oil, not only avoids the heat generated by the friction of a large amount of oil molecules, but also has a better lubrication effect. The oil-air lubrication of the bearing follows the principle of a small amount of oil at a time, and the oil is quantified in a very small amount each time, and the oil supply frequency is increased to meet the lubrication requirements of the bearing. This kind of lubrication method is that compressed air drives the lubricating oil film to the friction surface. The lubricating oil fully plays the role of lubrication. The compressed air can also take away the heat generated by friction and play a cooling role.

The selection of bearing oil-air lubrication, the advantages are summarized as follows:

1. The amount of lubricating oil consumed is low, which saves costs.

2. The lubrication effect is good. The design performance of the electric spindle is guaranteed.

3. Compressed air can take away the heat generated inside the electric spindle, effectively preventing the bearing from being deformed due to heat.

4. Positive pressure inside the bearing , To prevent the intrusion of impurities and so on.