Table 1 shows a comparison of Acme screw, ball screw, and planetary roller screw actuators as systems but does not take into consideration application specific requirements. Outcomes are derived from Moog’s actuation design experience and data provided by other manufacturers.

An electromechanical actuator system incorporating a planetary roller screw is found to be superior in many characteristics, including load capacity, service life, responsiveness (speed and acceleration), rigidity, impact resistance, heat resistance, space required, ease of maintenance, and customizability.

Planetary roller screw and ball screw systems (electromechanical systems) can dramatically reduce complexity of the control system of valves, pumps, filters, and sensors used in hydraulic and pneumatic systems. They provide significant benefits, including cost reduction and improved reliability. They also provide long service life, high efficiency, and improved ease of maintenance. Furthermore, elimination of high-pressure fluid reduces noise, prevents oil leakage, and is generally more environmentally friendly. Finally, they can be easily customized compared to hydraulic and pneumatic systems, with a planetary roller screw or ball screw being integrated directly into a motor, or applied to other specialized machinery.

In the absence of application-specific requirements, Table 1 indicates the choice between ball screws and planetary roller screws is quite clear. Ball screws should be considered for drive mechanisms that give priority to smoothness or efficiency, whereas planetary roller screws are suitable when high load capacity, long service life, and high speed are required. 

Ball screws generate heat due to contact between the ball bearings, whereas the rollers of planetary roller screws do not make any contact with each other, improving the heat resistance of planetary roller screws. However, ball screws are superior in terms of efficiency due lower rolling friction.

Rollers have approximately four times as many contact points as balls, the load is dispersed over an area that is approximately four times larger. This results in longer service life and a load capacity that is more than 10 times higher in favor of a planetary roller screw. Increased contact area also improves the rigidity and impact resistance of planetary roller screws.

In addition, ball screws make noise mainly due to the collision between the circulation tube and ball bearings. On the other hand, planetary roller screws emit noise mainly from the timing gear for rollers, but it does not grow exponentially and is therefore lower than that of ball screws.