Stiffness: The rigidity of the bearing is characteristic of the elastic deformation size under load. Since the rolling bodies are different from the roller contact, the rigidity of the roller bearing
is larger than the ball bearing. Bearings can increase the stiffness of the spindle by preload.
Bearing preload: The preload of the bearing can not only increase the rigidity of the bearing but also increase the installation of the bearing
precision. So the bearing of the machine spindle mounting is almost necessary to apply a preload.