Ball Screw Assemblies

It is instantly clear that a ball screw is not a straightforward one-piece tool. In fact there are a number of components and the entire apparatus is known as a ball screw assembly. The two principal parts of a ball screw assembly are the screw and the nut. The nut can move along the screw once one of these two parts is in motion. Usually the screw’s revolutions causes the nut to move sidewards, or the system may be swapped a process that is called back-driving.

Ball screw assemblies cannot be seen as being extremely complicated. There are ball bearings inside the nut, which are free to move within the assembly. The appearance of the screw is typical, with threads along its length. Within the nut similar threads have been created which create tracks for the ball bearings to follow. As soon as the screw begins to move the ball bearings are forced to travel along the grooves, and this is responsible for the motion of the nut along the screw. The ball screw assembly also contains a deflector that ensures the ball bearings continuously return to the top of the nut. Once the ball moves to the end of the nut it moves upwards once more. This is a circuit, that has the ball bearings moving in a cycle inside the nut casing. In many ways this is the basis of the ball screw assembly.
You can calculate the approximate lifetime of ball screw assemblies through determining the number of screw threads as well as the thread number of the ball nut barrel. For each time that a full journey along the screw has been completed, each section of screw thread has had each ball bearing travel along it once. However, the threads of the nut casing may have had the balls pass through them many times over depending on the length of the screw. In this way the proportional difference between the nut thread count and the screw thread count can give an indication how much more wear and tear is exerted on the interior of the ball nut which will give an approximation as to the relative lifespan of the nut when compared with the life of the ball screw. Different ball screw assemblies will therefore have different life expectancies, as indicated by the appropriate numbers.