A ball screw is a mechanical device that is primarily used to convert rotational motion to linear motion. Contrary to a regular screw or a lead screw which has high friction between the screw shaft and nut threads, ball screws are highly efficient to minimize friction loss. It comprises four main components—the ball screw shaft, the nut, the ball bearings, and the seal.
The Use And Application Of Ball Screws
Lead screws produce a sliding motion which effectively hinders the efficiency of an application; ball screws, on the other hand, generate a rolling effect that requires lesser torque and has a low maintenance rate.
The ball bearings play a pivotal role by reducing friction to a great extent, warranting smooth operation and accurate motion. To support radial and axial loads, ball screws SDA-V [บอลสกรู SDA-V, which is the term in Thai] are installed in high-performing machines that require linear motion, such as lathe machines, energy-conserving types of machinery, such as solar panels, wind turbines, and such.
How Does It Work?
Having understood what a ball screw is, let’s dive into its mechanism. Unlike a lead screw which has a variety of threads ranging from square, acme, or buttress, a ball screw uses a thread with helical grooves that spirals along its length. The ball, as well as the nut, are equipped with similar spiral grooves to cause minimal resistance.
As the shaft moves forward, the ball rotates in a circular motion continuously, moving in and out of the gap between the nut and the screw. This technique increases lubrication and reduces friction, ensuring the smooth functioning of the machine.
Apart from the ball bearings, the design of the ball nut is also crucial in determining how long will it take before it completely gives way. Under a high-stress load, the ball screw can gradually begin to wear off. This depends entirely on the number of revolutions the ball nut takes which is about 90% before it eventually gets fatigued.
Final Overview
When it comes to high efficiency, although lead screws are cheaper to make, they can convert only 20-80% of the total torque into linear thrust while the rest gets wasted on friction. This, in turn, causes overheating of the nut. Ball screws, however, limit the contact between the ball nut and the ball screw.
The compatibility between the balls and the thread design helps propel them along the length while also moving back through a return channel. The internal recirculation of the ball is highly considered and used, as it follows the natural trajectory of the ball, without any impact on lubrication.
