Kogelschroef

Kogelschroef, in English ball screw, is a precision mechanical actuator that converts rotary motion into linear motion through rolling contact between balls and a threaded screw. It consists of a screw shaft with a helical thread and a ball nut containing circulating ball bearings that move within matching grooves. When the screw rotates, the balls roll along the threads and recirculate through return channels, producing smooth, high-precision translation with relatively low friction. Preloading the nut by applying axial force or using multiple nuts eliminates backlash and improves stiffness and accuracy.

The design typically uses hardened steel components and precision-ground threads. The circulating balls provide rolling contact, which reduces friction compared with lead screws and enables higher efficiency, better repeatability, and greater load capacity for a given size. Preloaded ball nuts are common to increase rigidity and reduce play. Variants include different nut configurations, coatings for wear resistance, and combinations with electronic or mechanical backlash compensation.

Advantages of kogelschroeven include high efficiency, high stiffness, accurate positioning, and long service life when properly lubricated and protected from contamination. They are more expensive and sensitive to dirt and misalignment than simpler screw types, and require precise installation, lubrication, and regular maintenance to preserve performance. Common failure modes involve ball or race wear, nut wear, and coating degradation under insufficient lubrication or foreign particles.

Applications are widespread in industries demanding precise linear motion, such as CNC machine tools, robotics, semiconductor equipment, metrology stages, and high-precision assembly systems. Designers select ball screws based on required lead, load ratings, accuracy, preload, and environmental conditions.