ballscrews

Ball screws are a type of mechanical linear actuator that converts rotary motion into linear motion with high efficiency and precision. They consist of a threaded shaft and a matching ball nut. Ball bearings travel in the helical grooves within the nut and recirculate through return channels, allowing rolling contact rather than sliding friction. This reduces friction, increases stiffness, and enables high efficiency and long life.

The screw shaft has precision ground or rolled threads, and the nut contains balls and return elements. The system can be preloaded to remove backlash, improving position accuracy and stiffness. The result is high mechanical efficiency (often 90–99% depending on diameter, pitch, preload, and lubrication) and low wear when properly lubricated. Design considerations include preload, static and dynamic load ratings, backdrivability, and lubrication management.

Types include ground ball screws and rolled ball screws; preloaded ball nuts and single- or dual-nut configurations are common. Preload reduces backlash at the cost of higher friction and heat. Ball screws are used in CNC machines, aerospace actuators, precision machine tools, robotics, and high-precision automation. They are typically compared with lead screws; ball screws offer higher efficiency, higher stiffness, and longer life but at higher cost and complexity.

Maintenance involves clean lubrication, protection from contamination, and regular inspection. Life is influenced by load, speed, lubrication, alignment, and support bearings, with manufacturers providing dynamic and static load ratings and life formulas.