Current. Available for precision spindle system are dynamic bearing, rolling bearing, hydrostatic bearing, air bearing and magnetic bearing.
1. Magnetic bearing can only be used on very few professional machine tools due to its high cost,
2. The bearing capacity of air bearing is too low, so it is limited to light load superfinishing.
3. Hydrostatic bearing. Due to the complex structure, difficult processing and difficult adjustment, in the process of use, once the oil supply of an oil chamber is not smooth or blocked. It will cause the “holding shaft” between the main shaft and the bearing under the action of the pressure oil in the relative oil chamber, resulting in serious damage to the main shaft and the bearing. These disadvantages of hydrostatic bearing limit its wide application in production, and the dynamic stiffness is far less than that of the main shaft of hydrostatic bearing.
4. Rolling bearing. With the improvement of manufacturing accuracy, the use of centripetal thrust bearing is gradually increasing. However, it is difficult to meet the requirements of high-precision grinder due to the difficulty of ultra precision machining, poor accuracy retention and low service life.
5. The hydrodynamic bearing has high rotation accuracy (radial runout ≤ 0.005mm) and good axial stability. It is the main shaft support mode of many precision grinding machines.