What shape does the groove of the Ball Screw have?
There are three different shapes for the ball running surface: a point contact structure like for a ball bush, a circular arc groove, adopted for the LM Guide, with a curvature very similar to the ball diameter, and a gothic arch groove with two combined arcs. The Ball Screw uses a gothic arch groove structure. Point contact provides a small load rating. The circular arc groove becomes low in feed accuracy or axial rigidity because the contact point moves easily when an axial load is applied. For this reason, the gothic arch groove structure is adopted for the Ball Screw.