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Design and Theory

Ball screws convert rotary motion to linear motion and/or vice versa. A ball screw assembly consists of a screw and a nut with recirculating ball bearings. The connection between the screw and the nut is made by ball bearings, which roll in the matching ball forms in the screw and nut. The forces transmitted are distributed over a large number of ball bearings, giving a relatively low load per ball. Since Ball screws assemblies use rolling elements they have a low coefficient of friction .

A ball screw utilizes recirculating bearings

The following video provides a little detail about ball screws.

What is a  ball screw?

What is the difference between a ball screw and a lead screw?

In ball screws there are recirculating bearings.  In lead or ACME screws they operate only with sliding friction and do not have recirculating bearings.

ball screw compared to a lead screw

Ball Screws feature:
  • 90% Efficient
  • Rolling Contact
    • Life limited by fatigue - Predictable life
    • Lower starting torque
    • more load capacity
Lead Screw or ACME screw features:
  • 30-80% efficient
  • Sliding friction
    • life limited by wear - hard to predict life
The following video provides some information on the differences between lead and ball screws.  And when one would be better in an application.

Lead vs. Ball Screw Technology

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