1. Fixed and free installation mode way 

The fixed bearing can bear both axial force and radial force, and ball screw bearing is mainly used for short screw bearing with small stroke or closed machine tool, because when the mechanical positioning mode of this structure is adopted, its accuracy is unreliable, especially the screw bearing with large ratio of length to diameter (ball screw is relatively slender), its thermal deformation is very obvious. However, if it is a 1.5 m long screw, it is a normal phenomenon to change 0.05~0.1mm in different cold and hot environments. However, because of its simple structure, the installation and debugging competition, most high-precision machine tools still use this structure. However, it is not necessary to note that the use of this structure must be provided with gratings and closed loops for feedback in order to provide sufficient screw performance.

2. Fixed and supported way

The fixed ball screw bearing can also bear the axial force and the radial force at the same time, while the support can only bear the radial force, and can do a small amount of axial floating, and can reduce or avoid the bending caused by the self-weight of the screw. In addition, the thermal deformation of the screw can be extended freely. Therefore, this is a widely used structure. For example, at present, this structure is used in small and medium-sized CNC lathes, vertical machining centers and so on.