In your experience with ball screws, you’ve probably encountered one of the great debates surrounding these devices: manufacturing methods. How are ball screw assemblies made, and what’s the difference between the different fabrication processes? Is one better than the other? Learn the answers to these questions and more in this article.
Parts of a Ball Screw Assembly
A ball screw assembly is a type of linear actuator used in machines across industries to translate rotational motion to linear motion. It’s made up of three main parts: a screw shaft, a nut, and ball bearings between the two. The basic design of each ball screw assembly is the same, but the details—like the shape of the nut, type of ball bearing return system, amount of preload, and other elements—can vary.
Two Manufacturing Methods
When it comes to how ball screw assemblies are made, there are two main manufacturing methods for the threads on the screw shaft and interior of the nut. The products of these two methods are rolled and ground ball screws. Read on for an explanation of each.
Rolled Ball Screws
Rolled ball screws are created from an uncut blank by rotating tool dies. In this process, the blank moves through the rotating dies, which shape the material into a pattern of helical threads. Both the external threads of the screw shaft and the internal threads of the nut are fashioned in this way. The rolling process is considered very efficient, as it does not physically remove any material from the blank. While rolling is the less expensive of the two methods, it generally results in screws that are less accurate than ground ball screws.
Ground Ball Screws
In contrast to rolled ball screws, ground ball screws are created with the aid of a grinding wheel. This hard, abrasive cutter travels the length of the horizontal blank, cutting out a few threads of the screw at a time. Because in this process in which material is physically removed from the blank, it is a more time-intensive and more expensive process. Ground ball screws typically have higher accuracy than their rolled counterparts.
So, which of these manufacturing processes is better? In short, it depends on your needs from a ball screw assembly. If your machine requires high amounts of accuracy, a ground ball screw is likely the best choice for you. If you don’t need that extra precision for your machine, a rolled ball screw is a perfectly effective and less expensive option.
Here at Wedin International, Inc., we specialize in the creation of all types of ball screw and nut assemblies. Simply give us your request, and we’ll make it our duty to fulfill it to your satisfaction.