More about Ball Screws

Click here to find Ball Screws Manufacturers | Discuss Ball Screws & Other Topics

Ball screws are a specialized form of screw whose threads are designed to provide smooth movement for an attached, ball-bearing-filled nut, known as a ball nut. Used to convert rotation into longitudinal motion, ball screws achieve stepless positioning with the help of the ball nut. Ball nuts are similar to normal nuts, but hold ball bearings specialized to ride in the groove of the ball screw rather than threads. These bearings approximate rolling contact with the screw threads and enable the nut to move across the screw with minimal friction, far less than would be encountered by a lead screw.

When the ball nut is turned around a ball screw, it propels the screw in a certain direction. The amount of load that this movement can drive is determined by the combined properties of screw and nut; it is not dependent on only a single factor. Ball screws can be manufactured in a variety of materials, although steel and stainless steel alloys are predominant materials of choice. This is also true for ball nuts.

Ball screw attributes are described with various terms. A screws’ lead is the linear distance the screw moves when the nut is turned one rotation. The direction of the thread, whether left hand or right hand, determines what direction the nut will move when the screw is turned clockwise and counterclockwise. In a right hand threaded screw, the nut will move away from the turned end when it is turned clockwise. A ball screws’ lead, load capacity, thread size and direction, diameter and composition all affect its performance. These parameters should be considered during screw selection.