What is the load-bearing capacity of the machine tool spindle shaft?

What is the load-bearing capacity of the machine tool spindle shaft?

The spindle bearings of machine tools mainly bear the following forces during operation:

Radial force: During the rotation of the machine tool spindle, radial force is generated due to the cutting of the workpiece and the vibration of the machine tool itself. 

This force will cause relative displacement between the inner and outer rings of the bearing, affecting the stability and lifespan of the bearing. In order to reduce the 

impact of radial force on bearings, appropriate pre tightening and lubrication measures are usually adopted in spindle design. ‌

Axial force: In the process of machine tool machining, the feed and cutting of the workpiece will generate axial force, which will cause the shaft to bear compression or 

tension. Precision angular contact ball bearings and tapered roller bearings can withstand large axial forces, ensuring the stability of the spindle during high-speed 

rotation. ‌

Overturning moment: Overturning moment is caused by the imbalance of the workpiece or defects in the machine tool structure, which can cause the spindle to tilt 

or shake. Due to its special structural design, tapered roller bearings can effectively resist overturning moments and ensure the stable operation of machine tools. ‌

The force characteristics of spindle bearings in different types of machine tools

Precision angular contact ball bearing: This type of bearing can withstand both radial and axial loads simultaneously, making it particularly suitable for high-speed and 

high-precision machine tool spindles. The contact angle is mostly 15 ° and 25 °, and the smaller the contact angle, the more suitable the bearing is for high-speed 

operation. ‌

Cylindrical roller bearings: mainly used for machine tool spindles with high rigidity and load-bearing capacity. They can withstand large radial loads and allow for 

some axial displacement of the shaft within the casing. ‌

Conical roller bearings: suitable for applications that require bearing large combined radial and axial loads, especially in vertical grinders and heavy-duty machine 

tools. Conical roller bearings can provide high rigidity and stability. ‌

Thrust angular contact ball bearings: mainly used to withstand high axial loads and provide high-precision support, commonly found in the spindle of high-precision 

grinders and machining centers.