Ballscrew Journal Design

Steinmeyer recommends using INA support bearings. Upon request, our engineers will recommend as to which bearing to use and how to design the journals accordingly.

In machine tool applications, only bearings providing a similar axial stiffness to the ballnut should be used. The size of the bearing is to be determined - for better cost effectiveness - according to the major (nominal) diameter of the screw, as this is generally used as a shoulder to preload the bearing pack (see fig. on top).

If the bearing's recommended minimum shoulder diameter comes close to the major diameter of the screw, the ballthread should not penetrate the shoulder in order to allow for a full 360° surface. This will prevent problems such as cocking or skewing (see fig. in the middle).

In cases of the bearing's recommended minimum support (shoulder) diameter being larger than the screw's nominal or outside diameter, we will provide a solid shoulder using a bushing shrunk on the journal, so that it can be ground to optimum perpendicularity. Please avoid - if possible - to design wrench flats on this diameter, as the ballscrew must be machined from larger diameter raw material, which may increase costs (see the bottom fig.).