What do you know about ball screw transmission ?

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"The transmission mechanism of a ball screw uses rigid balls as intermediate elements between the screw and the nut, transforming sliding friction into rolling friction for transmission.

Both the screw and the nut have helical grooves on their surfaces with curved profiles. The combination of these two curved grooves forms a raceway. Inside the nut, there are multiple ball bearings, resulting in rolling friction between the screw and the nut. At both ends of the grooves in the nut, there are ball return tubes that allow balls to exit one end of the helical groove in the nut and return along the tube to the other end of the raceway. As a result, when the ball screw rotates relative to the nut, it undergoes continuous rolling motion within the helical raceway.

Ball screw transmission offers the following advantages:

High transmission efficiency: The transmission efficiency of ball screw transmission is generally between 92% and 99%, whereas conventional sliding screw transmissions typically have transmission efficiencies between 20% and 40%.

High transmission precision and smooth motion without creeping. Ball screw transmission relies primarily on rolling friction, resulting in very low friction resistance that is nearly independent of the movement speed.

High manufacturing cost: Ball screws and nuts require high precision and low roughness, which increases manufacturing costs. The helical grooves on the screw and nut must be precision-ground to form the raceways.

Lack of self-locking: Especially for vertical screw applications, due to the relationship between gravity and inertia, a braking mechanism is needed to prevent the components from self-locking after transmission stops.

No empty travel during reversal: Preloading the ball screw and nut eliminates axial backlash, ensuring smooth reversal without dead zones and improving axial transmission accuracy and stiffness.

Reversibility: Due to the low friction loss in ball screw transmission, it can easily convert rotary motion into linear motion or vice versa. Both the screw and the nut can be used as driving or driven components.

Long service life: Ball screw transmission has a long service life due to minimal rolling friction losses.

Because of these advantages, ball screws are widely used as efficient and precise transmission mechanisms in precision machine tools and CNC machines."