rollerscrew

Roller screw, or roller-screw, is a type of linear actuator that converts rotary motion into linear motion using rolling elements, typically cylindrical rollers, placed between a screw shaft and a mating nut. The roller mechanism provides continuous contact along the load path, enabling high load capacity and stiffness compared with traditional sliding nuts and often with high efficiency.

A roller screw consists of a precision screw with helical grooves and a nut containing multiple rollers held in cages. The rollers roll between matching grooves on the screw and in the nut, while a recirculation system returns the rollers after they pass through the load zone. This arrangement distributes load over multiple contact points and reduces sliding friction, producing low wear when properly lubricated. Preload can be added to remove backlash and improve rigidity.

Roller screws are generally more complex to manufacture and assemble than ball screws, and require careful alignment and sealing. They benefit from high load ratings, good stiffness, and long life in demanding environments. Typical failures relate to wear of raceways, roller cage wear, and seal degradation if lubrication is insufficient.

Common applications include machine tools, aerospace and defense actuators, large automotive or industrial presses, medical equipment, and precision robotics, where high load, long life, and precise motion are required. Designers choose roller screws based on load, speed, accuracy, and duty cycle, balancing efficiency, heat generation, and maintenance needs.