Roller Screw Advantages
High Efficiency for Longer Life
There are significant operational differences between a planetary roller screw and a ball screw. In a ball screw, the steel balls contact one another and rotate, with mating surfaces moving in opposite directions. Even when well-lubricated, the resulting friction creates significant heat and wear as rotational speeds increase. In a roller screw, the planetary rollers are constrained by journals at each end of the roller. Since one roller never touches another, friction is eliminated.
Higher Speed for Increased Efficiency and Productivity
Roller screw technology is capable of higher rotation speeds. They eliminate the need for loading and unloading of balls and the sharp turns of ball return tubes used by ball screws. As a result, planetary roller screws operate efficiently up to 6,000 rpm.
Greater Load Distribution for Higher Load
Capacity and Longer Life
A comparably sized ball screw has, at most, just 50 balls in pressure contact at any time, so its load capacity and life are compromised. Conversely, the longer life and greater shock resistance of a roller screw results from its larger pressure transmission area. Contact is made simultaneously at each thread on every roller. On average, there are 200 contact points in a 1 inch diameter, 1.5 inch long roller screw. Therefore, the load is distributed over approximately 4 times the area which can result in up to 15 times longer life and up to 15 times greater load carrying capacity. Additionally the roller screw design delivers improved stiffness for greater precision and durability.
Lower Noise for Quieter Operation
Ball screw noise is generated by the balls colliding in the return tubes. Conversely, the sound of a roller screw comes from the roller timing gears which are much higher frequency (typically 10 times). Also the noise of a roller screw does not grow exponentially with its speed. As a result, roller screws are generally much quieter than ball screws.