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Walter Tools Blog

Engineering Kompetenz

Ball screw - threading meets the highest precision

October 2022
20
WalterTools
Author: WalterTools
Company: Walter AG
Ball screw - threading meets the highest precision

What is a ball screw?

A ball screw is a screw mechanism in which inserted balls transmit the force between the screw and the nut. There are no standardized thread profiles (different pitches, ball diameters and contact angles).

Application area:

The application area vary depending on the accuracy of the profile. A distinction is made as to whether noises may be present in the application area. Here the quality requirements are lower compared to noiseless ball screws.

Noise may be present

  • parking brake
  • trunk lid

Noise is not allowed

  • electro mechanical steering
  • brake booster
  • transmission
  • robotics

Function:

A motor drives the spindle either directly or via belt drives. Between the spindle and the nut, balls move (roll) in the grooves, which move axially when the spindle turns. The return channel in the spindle nut transports the balls back and thus closes the circuit in which the balls circulate.

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Advantages ball screw:

  • Ball screws can be adjusted with very little play
  • Low friction and therefore less wear, heat development and energy consumption
  • Less friction makes loosening easier

Disadvantages ball screw:

  • Ball screws usually require more space than other systems
  • Significantly more complex manufacturing process (highest tolerances and precision) and therefore more expensive

Threaded spindle and nut manufacturing methods:

Thread whirling, rolling and grinding are common methods for creating raceway grooves in the threaded spindle. Both the ball and raceway surface are typically hardened, with the raceway often being coated on high-speed spindles.

Ball screw nuts, on the other hand, can be manufactured by turning, milling and forming threads. The manufacturing method depends on the quality requirements.

Production with the highest quality requirements (noise is not allowed):

  • Thread turning with indexable inserts
  • Or thread milling with a single-row tool
  • Or thread milling with a multi-row tool
  • Additional finishing with a thread former or grinding

Production with less high quality requirements (noise allowed):

  • Thread turning with indexable inserts
  • Or thread milling with a single-row tool
  • Or thread milling with a multi-row tool

Walter solutions to achieve the highest quality

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Example component (multi-row thread milling and finishing):

Summary manufacturing ball screw nuts with Walter solutions

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For further information about this topic contact:

Marcel Lehmann

marcel.lehmann@walter-tools.com

+49 151 74497900

+49 7835/77-156

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