Spindle bearing is a very important part of CNC machine tool. The selection of different bearings has different effects on the running speed, load capacity, temperature rise, stiffness and service life of the machine tool. There are five kinds of bearings commonly used in machine tool spindle: tapered roller bearing, bidirectional thrust angular contact ball bearing, double row cylindrical roller bearing and deep groove ball bearing. Different bearing functions are not the same, and the machine tools and equipment that can be used are not the same. Next, let's analyze and understand one by one and see what there are in each point.

1. Tapered roller bearing

It can bear both radial and axial loads, and double row tapered roller bearings can bear bidirectional axial loads. Because of the sliding friction between the tapered roller and the inner ring retaining edge, the limited speed is often lower than that of the cylindrical roller bearing of the same size. The hollow tapered roller bearing can be cooled with oil to reduce the temperature rise, thus increasing the allowable speed. However, the manufacturing process of this kind of bearing is complex, and the requirement of machine tool lubrication system is also high, which is only used on horizontal spindle with special requirements.

2. Bidirectional thrust angular contact ball bearing

The 230000 bidirectional thrust angular contact ball bearing is usually selected, the contact angle is 60°, which is composed of a seat ring with lubricating oil hole, two shaft rings, a separate ring and two sets of steel balls and cage assemblies. Selecting the appropriate ring height can make the bearing have the required preload after assembly.

This kind of bearing can bear bidirectional axial load, has good rigidity, low temperature rise under normal lubrication, high speed, and easy to install and disassemble. As a new structure, it is often used in grinder, lathe, boring machine, milling machine, drilling machine and other spindle, and is often combined with double row cylindrical roller bearings.