Ball screws provide motion control in a variety of machines, including aircraft, vehicles, and robotics. They carry the load using circulating ball bearings which help in minimizing friction and increasing efficiency. In this article, we’ll discuss the four components of a ball screw assembly to gain a greater understanding of how a ball screw operates.
Ball Screw Shaft
The main body of the ball screw is its shaft, which consists of a long steel bar with continuous grooves (ball grooves) in it, forming a helical pattern (the thread). The shaft receives the force, allowing the ball screw to rotate.
The Nut
Inside the nut, there are ball grooves to match the grooves of the shaft. The nut is a part of the recirculatory system that holds a ball bearing. Without the nut, the balls would continually fall out rather than recirculate.
The Bearings
The ball bearings (balls) are what make the ball screw unique from lead screws. Balls are made of steel, and without them, as the nut and shaft move, the friction would be too much. With the help of the ball bearings, a ball screw can efficiently rotate with little to no friction.
The Seals
On a ball screw, the seal’s job is to protect the screw from debris and any objects or matter that might otherwise enter the space between the ball screw and the nut. There are two types of seals: standard and high performance.
- Standard Seal — the standard seal comes in two forms: plastic or brush. The plastic form is a non-contact general-purpose seal used to block debris through obstruction. The brush seal brushes debris away and off of the track and is used for rolled ball screws.
- High Performance — high-performance seals are custom made for a specific screw nut and lead combination. They are made with a lip that blocks debris and contaminants while increasing torque only slightly. A high-performance seal is needed for messy jobs such as woodworking or welding.
As mentioned, people use ball screws in many applications when a stable linear translation is needed. As we understand the four components of a ball screw assembly, it gives us a greater appreciation for how a ball screw works and why each component matters.
At Wedin International, we offer acme screw products and any other ball screw and nut assembly your machines require. Contact us for more information on how we can help with your machine component needs.