ball nut

Reprint of Danielle Collins post, Linear Motion Tips, on Friday, December 11, 2015

As an integral part of industrial machines and processes, ball screw assemblies often operate in environments with elevated temperatures. Heat can be generated by other mechanical and electrical components in the machine, and in some cases, is a byproduct of the process itself. And, like other motion products with sliding or rolling friction, ball screws generate heat of their own as they run. This heat, and especially the change in temperature that occurs over time, can have a detrimental influence on the screw’s function. But there are ways to mitigate heat and reduce its effect on life and accuracy.

Operating temperature recommendations for ball screw assemblies vary among manufacturers, but the typical upper limit for the most common ball screws is 80° C for short, instantaneous exposure, and 50° C for continuous duty. For standard annealed screws, a temperature over 100° C can cause a decrease in tensile...

The ball screw drive is an assembly that converts rotary motion to linear motion and vice versa.  The ball screw drive consists of a ball screw and a ball nut with recirculating ball bearings. 

The connection between the screw and the nut is made by ball bearings that roll in the matching forms in the screw and ball nut.  The forces transmitted are distributed over a large number of ball bearings, giving a comparatively low relative load per ball.  With rolling elements the ball screw drive has a very low friction coefficient. 

Ball screw drives typically provide mechanical efficiency of greater than 90% so their higher initial cost is often offset by reduced power requirements.

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Reprint of Thomson Industries, Inc. Article by Jeff G. Johnson