Ball Screw Support
Ball screws have many advantages over gears: high efficiency, precise positioning and the ability to generate preload. However, these advantages only become apparent when two conditions are met: the drive screw is rigidly fixed in the axial and radial directions and does not sag. Screw supports mounted at both ends of the drive screw ensure that the kinematics meet these conditions. These supports are housings with bearings and mounting holes for attachment to the frame or drive housing. Execution material – structural steel.

Classification and arrangement of screw supports
Depending on the position of the screw shaft and on which end the support is mounted (free or slave end), they are divided into four types:

BK series;
BF series;
FK series;
FF series.
The structural differences between them lie in the design of the housing itself, the type of bearing used and the position of the mounting holes. Functionally, they solve different problems; the name of the series determines which support is used in which case.

In these abbreviations, the first letter indicates the position of the screw shaft. The BK and BF series are used to build horizontal motion solutions, the FK and FF series are used for vertical drives. The second letter determines which end of the screw the support applies to. The brackets BF and FF are attached to the frame and perform a supporting function. The BK and FK fix the drive end of the screw and are mounted on the drive body.

In the first case, a single row radial bearing is used in the support. The bearings have a minimum clearance in the axial direction within the support housing. This is to eliminate clearance due to changes in screw length caused by the effects of thermal expansion or elastic deformation.

The second case (BK and FK series) uses double row angular contact bearings. These supports carry radial and axial loads. The bearings are firmly seated in the housing with no clearance.

When servicing high-precision equipment, it is not recommended to replace the cheaper bearings and make your own supports. Deviations of 0.01 millimeters in machining floor dimensions cause radial and axial runout, which reduces machining accuracy and leads to accelerated wear of the ball screws.