What are the common bearing types in NC turntable

CNC turntable is widely used in various CNC milling machines, boring machines, various vertical turning, vertical milling and other machine tools. In the design of turntable, there are several types of bearings used:
What are the common bearing types in NC turntable
1. Thrust ball bearing + cylindrical roller bearing: thrust ball bearing can bear certain axial force, so the bearing is mainly used to bear the weight of workpiece; Cylindrical roller bearings are mainly used for radial positioning and bearing external radial forces (such as cutting force, milling force, etc.). This kind of design is widely used and the cost is relatively low.
2. Hydrostatic bearing + precision cylindrical roller bearing: hydrostatic bearing is a sliding bearing that relies on external supply of pressure oil and establishes hydrostatic bearing oil film in the bearing to realize liquid lubrication. Hydrostatic bearing always works under liquid lubrication from start to stop, so it has no wear, long service life and low starting power; In addition, the bearing also has the advantages of high rotation accuracy, large oil film stiffness and suppression of oil film oscillation. The cylindrical bearing is used to ensure the precision and good bearing capacity of the rotary table. The turntable with this design can bear high axial force. The weight of some workpieces is more than 200 tons and the turntable diameter is more than 10 meters.
3. Cross roller bearing: cross roller bearing is also widely used in turntable. The cross roller bearing is characterized by two raceways and two rows of cross arranged rollers in the bearing. Compared with the traditional thrust bearing + radial centering bearing combination, the cross roller bearing has compact structure and small volume, and simplifies the design of the workbench, thus reducing the cost of the turntable.
Generally speaking, as the spindle and core component of NC turntable, bearing plays an important role in the operation performance of NC turntable. In order to select the appropriate size and type of bearing, we need to comprehensively consider various working conditions.