What is a Ball Spline and How Is It Used

A ball spline is a device which enables linear motion on a single shaft. They are well-suited for applications that require high speed, vibration, and shock loading. Though ball splines look and act somewhat similarly to a traditional rolling bearing guide, they are designed with grooves that keep the recirculating balls along a restricted track. By moving in this track, the round nut of the device does not ride freely on the shaft; instead, the spline nut is constrained along a specific path. In a typical ball spline, the nut can only move linearly, but a rotary ball spline allows rotational movement on the shaft in addition to linear movement.

How Do Ball Splines Work?

In order to achieve smooth, linear motion without rotation, ball splines incorporate a grooved pathway for the recirculating balls to move through. These pathways loop along the length of the shaft rather than creating a ring around it so that even as the balls rotate, they are always moving in a linear direction along the length of the shaft. In order to add the possibility of rotational movement, rotary ball splines add an additional ring to the spline nut which has bearings that can roll around the diameter of the shaft. This allows for steady, linear movement of the interior while the exterior nut can rotate when needed.

Benefits of Ball Splines

Ball splines are very useful for their ability to handle large loads with great control. This is because the recirculating balls of the spline nut ride in grooves, so there is a much larger contact area as compared to ball bushings. As a result, ball splines have much higher load capacities than ball bushing assemblies of the same size. Even so, the main reason that designers and engineers use ball splines is their ability to prevent rotation, or otherwise in the case of rotary ball splines, to provide both linear and rotary motion in one device. Traditional linear bushings are almost always used in dual-shaft configuration in order to prevent the bearings from rotating. Since ball splines are inherently anti-rotation, they can be used in single-shaft configurations. Overall, replacing two shafts with one allows for a smaller footprint, less weight, and easier alignment and assembly.

Common Applications

Due to their restricted movement, ball splines are often used in manufacturing, robotics, honing machines, and more. One specific example of their use is in paper manufacturing because the spools of paper need the freedom to move horizontally left-to-right, but not rotate. To prevent rotation, two traditional linear shafts would be needed, but spline shafts can support the load with just one. Conversely, rotary ball splines are often used as a solution for specialized robotics and automatic tool changers. With the ability to move along several different axes, they can help actuate specific movements with high precision. Pick-and-place or assembly applications can also benefit from rotary ball splines. For example, transferring a part from one workstation to another might involve picking up the part from one station, rotating to the position of the second station, and placing the part on that second workstation. This procedure would combine vertical and rotary motion and can therefore benefit from use of a ball spline.

Conclusion

Overall, ball splines have found their place as a highly useful mechanism for their high load capacities in some cases and the combination of linear and rotary motion capabilities in others. When you are in need of high-quality ball splines or other industrial and aviation components, you can rely on Integrated Purchasing as your strategic sourcing partner. With robust purchasing power and a widespread network of supply locations, Integrated Purchasing promises shipping solutions that meet your strict operational requirements, even for AOG situations. Begin the purchasing process with us today when you use the Instant Request for Quote (RFQ) form on our website. With representatives on standby 24/7x365, you can always expect a response in 15 minutes or less from our receipt of your completed form.