Design World

  • Home
  • Articles
    • 3D CAD
    • Electronics • electrical
    • Fastening & Joining
    • Factory automation
    • Linear Motion
    • Motion Control
    • Test & Measurement
    • Sensors
  • 3D CAD Models
    • PARTsolutions
    • TraceParts
  • Leadership
    • 2020 Winners
    • 2019 Winners
    • 2020 LEAP Awards
  • Resources
    • DIGITAL ISSUES
      • EE World Digital Issues
    • Future of Design Engineering
    • 2020 LEAP Awards
    • MC² Motion Control Classroom
    • Motion Design Guide Library
    • Podcasts
    • Suppliers
    • Webinars
  • Women in Engineering
  • Ebooks / Tech Tips
  • Videos
  • Subscribe
  • COVID-19

How to account for shock and vibration loads in ball screw drives

By Danielle Collins | May 7, 2020

Share

Calculations of ball screw service life and permissible static load take into account loads and forces that are predictable and quantifiable — thrust loads due to acceleration, process forces, and forces generated when holding a load in place, for example. But some applications are also susceptible to loads caused by shock and vibration — loads that are difficult to predict and quantify.

Shock and vibration loads can occur during standstill (static loads) or when the machine is moving (dynamic loads). In ball screw applications, shock, or impact, is often caused by sudden deceleration and hard stops, such as when a machine jams (preventing the screw from moving despite the motor applying torque) or when a pressing application doesn’t allow sufficient deceleration time at the end of the stroke.

shock vibration ball screw

Brinelling is often caused by shock or impact loads that exceed the static load capacity of the ball nut.
Image credit: Schaeffler

Vibrations are inherent in machine tool applications, where cutting or grinding operations induce vibrations in the tool, which “feeds” those forces back into the screw. Regardless of the cause, the consequence of vibratory loads is typically false brinelling, whereas severe static overload (shock or impact load) often results in true brinelling.

Both conditions produce regularly spaced indentions in the raceway of the screw shaft and can result in premature fatigue failure of the screw. Screws that experience vibrations when not moving are at an even greater risk of false brinelling, because when the screw and nut aren’t moving, there is no lubrication layer to help protect against damage to the raceway. This is why screw manufacturers often recommend shorter, more frequent lubrication intervals for ball screws that are subjected to vibration loads.

When calculating the L10 life of a ball screw, some manufacturers recommend multiplying the applied axial load by a “load factor” ranging from around 1.2 for applications with low shock and vibration forces, to 3.5 or 4 for applications with the potential for high shock loads and vibrations.

shock vibration ball screw

L = rated life of ball screw (rev)

C = dynamic load capacity (N)

F = applied axial load (N)

fw = dynamic load factor

Similarly, when comparing the applied static load to the static load capacity of the screw, manufacturers recommend that the applied static load be multiplied by a load factor ranging from 2, for low vibration and shock loads, up to 7 for machine tool applications that can encounter significant vibration or shock loads.

shock vibration ball screw

F0max = maximum permissible static load (N)

C0 = rated static load capacity (N)

S0 = static load factor


Loads due to shocks and vibrations can occur in both the axial and radial directions, but ball screws are designed to withstand only axial loads. This is why most ball screw applications incorporate linear guides — to support any radial loads that the system experiences. When sizing linear guides to be used in conjunction with a ball screw drive, it’s important to consider the potential for these additional loads due to shock and vibration.


planetary roller screw

Planetary roller screws are capable of withstanding higher loads because the rollers provide more contact points.
Image credit: Tolomatic

For applications that experience very high shock and vibration loads, planetary roller screws can provide better performance and longer life than ball screws. This is because planetary roller screws have significantly more contact points — with rollers carrying the load — so they can withstand higher dynamic and static loads.

Feature image credit: Thomson Linear

MOTION DESIGN GUIDES

“motion

“motion

“motion

“motion

“motion

“motion

Enews Sign Up

Motion Control Classroom

Design World Digital Edition

cover

Browse the most current issue of Design World and back issues in an easy to use high quality format. Clip, share and download with the leading design engineering magazine today.

EDABoard the Forum for Electronics

Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more

EDABoard: Forum for electronics

Sponsored Content

  • Configuration Management: Configuration Integrity IS A Core Driver for Business Success
  • How to Choose a Linear Actuator
  • Create your perfect machine with Advanced Engineering
  • How a ME/EE turned passion for design into his own bike company
  • Everyone Can Save on Cable Costs. Here’s How
  • How and Why You Should Use a Wave Spring for Bearing Preload
Engineering Exchange

The Engineering Exchange is a global educational networking community for engineers.

Connect, share, and learn today »

Tweets by @DesignWorld
Design World
  • Advertising
  • About us
  • Contact
  • Manage your Design World Subscription
  • Subscribe
  • Design World Digital Network
  • Engineering White Papers
  • LEAP Awards

Copyright © 2021 WTWH Media, LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media. Site Map | Privacy Policy | RSS

Search Design World

  • Home
  • Articles
    • 3D CAD
    • Electronics • electrical
    • Fastening & Joining
    • Factory automation
    • Linear Motion
    • Motion Control
    • Test & Measurement
    • Sensors
  • 3D CAD Models
    • PARTsolutions
    • TraceParts
  • Leadership
    • 2020 Winners
    • 2019 Winners
    • 2020 LEAP Awards
  • Resources
    • DIGITAL ISSUES
      • EE World Digital Issues
    • Future of Design Engineering
    • 2020 LEAP Awards
    • MC² Motion Control Classroom
    • Motion Design Guide Library
    • Podcasts
    • Suppliers
    • Webinars
  • Women in Engineering
  • Ebooks / Tech Tips
  • Videos
  • Subscribe
  • COVID-19
We use cookies to personalize content and ads, to provide social media features and to analyze our traffic. We also share information about your use of our site with our social media, advertising and analytics partners who may combine it with other information that you’ve provided to them or that they’ve collected from your use of their services. You consent to our cookies if you continue to use this website.OkNoRead more