The difference between ball screw and roller screw

If you need to drive an axial load of 500kN and a stroke of 1500mm, do you use a roller screw or a ball screw?

If you speak of roller screws instinctively, you may not be familiar with high-capacity ball screws as an economical and simple choice.

Under dimensional constraints, roller screws have been promoted as the only technical choice to deal with large loads.

But in fact, technological progress has made special ball screws a candidate for high-load applications. The important thing is that under the same performance, a high-load ball screw is usually half the cost of a roller screw.

What is the difference?

The ball screw consists of a threaded metal shaft and a nut. When the motor drives the shaft to rotate, the nut moves along the shaft.

According to the application of industrial automation, the nut is connected to the workbench, robot arm or other load. The steel ball circulating in the nut contacts the thread and provides load. The coefficient of friction between components is very low, which can usually increase system efficiency to more than 90%.

Therefore, the load capacity of the ball screw is a function of the diameter of the steel ball, the number of steel balls and the surface contact area. The combination of these parameters determines the load capacity of the ball screw and also determines its service life.

It consists of a threaded metal shaft and a nut. When the motor drives the shaft to rotate, the nut moves along the shaft. The nut is connected to the workbench, robotic arm or other load. According to the diameter and lead of the ball screw shaft in use, we provide ball nuts with three different circulation systems.

For higher loads, design engineers use roller screws for many applications. In the roller screw, the load-bearing component is a set of recirculating rollers instead of steel balls. The surface contact area of the roller is larger than that of the steel ball, which increases the bearing capacity and prolongs the service life.

The roller screw is composed of a set of circulating rollers. Compared with steel balls, threaded rollers have more surface contact area. Thereby improving the service life and carrying capacity.

But these benefits are relative. Compared with simple and reliable ball screws, roller screws require more precise processing and more complex assembly. This leads to a higher overall cost of the roller screw and a larger size package for final installation.