Bending of screw due to own weight

Where ball screws are installed horizontally there is bending (f_max) caused by their own weight. While this effect is negligible where ball screws are of moderate length and weight, this bending becomes extremely important in larger screws as it leads to undesired radial (overhang) loads which influence both pitch error and the nuts.

Where bending exceeds permissible values it is necessary to provide intermediate supports.

F   

weight of screw itself (N)

d₀

nominal diameter of screw (mm)

l₁

free, unsupported length (mm)

f_max

max bending (mm)

kf

bending coefficient