What Are Ball Screws and How Do They Work?

A ball screw is a form of mechanical actuator that combines the use of a screw with ball bearings. Consisting of a screw shaft and a nut that contains one or more balls which roll between their matching helical grooves, ball screws function by converting rotational motion to linear motion. They accomplish this by using rolling balls in the helical grooves of the screw to replace sliding friction with rolling friction. As a result, ball screws are useful for transmitting motion smoothly with less wear on internal components.

The main components of ball screws are the screw shaft, nut, and ball bearings. More specifically, the screw shaft is a long, cylindrical piece incorporating a continuous groove that winds down the length of the shaft in a helix. The ball groove serves as the pathway for the rolling ball bearings which are often made of metal, glass, ceramic, or plastic depending on the device. Lastly, there is the nut that encases the shaft and ball bearings which moves linearly along the shaft when the system is in motion. This nut will feature a grooved pathway that matches that of the threaded screw portion, allowing the balls to fit perfectly in place within their track.

Ball screws have become popular in many operations because of their high accuracy and precision which results in a minimal lead error. Lead error refers to the difference between the theoretical and actual distance that the nut has traveled when the screw shaft has rotated. Whereas a device might be predicted to move a certain distance in perfect conditions, there can often be small changes depending on external factors. Nevertheless, there are several techniques which can further guarantee the accuracy of a ball screw.

First, one can preload a ball screw by applying axial force on the balls, grooves of the screw shaft, and nut to make it compact. The purpose of this technique is to increase rigidity and eliminate any lost motion caused by the clearance between the ball and the grooved pathways. Aside from preloading, one can also employ oil and grease lubricants to lessen the overall wear caused by the friction of the balls rolling within the pathways. Lubrication also helps cool the components by dissipating heat into the surrounding air. Finally, one could increase the mounting accuracy of their components by checking that all bearings, couplings, nut brackets, and more, are oriented correctly with each other. Misalignment between these parts can cause noise, vibration, positioning errors, and even mechanical failure, so it is crucial to ensure a proper fit.

Ball screws are unique for their use of rolling ball bearings to convert sliding friction into smooth, rotational friction that ensures a longer service life and better overall capability. Additionally, this design guarantees high precision when maintained with the proper lubrication and fit within a machine. If you are in need of hardware for your application, look no further than Single Source Spares. As a leading supplier of aviation parts, electronics components, IT hardware, and more, our vast inventory includes a wealth of ball screws and other products. For dependable items you can rely on, kickoff the procurement process with us today to learn how Single Source Spares can easily match your deadlines and part requirements.


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