• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Motion Control Tips

Automation • Motion Control • Power Transmission

  • News
    • Industry News
    • Editor Blogs
    • Video
  • Controls
    • HMIs
    • PC-Based Controllers
    • PLCs + PACs
    • Stand-Alone Controllers
    • Software
  • Drives
    • Servo Drives
    • Stepper Drives
  • Encoders
    • Absolute Encoders
    • Incremental Encoders
    • Rotary Encoders
  • Mechanical
    • Bearings
    • Brakes + Clutches
    • Belt + chain
    • Couplings
    • Gears + Gearing
    • Lubrication
    • Shock + Vibration Mitigation
    • Springs + Rings + Seals
  • Linear
    • Actuators
    • Linear Motors
    • Linear Encoders
  • Motors
    • AC Motors
    • DC Motors
    • Brushless Motors
    • Gearmotors
    • Piezo Motors
    • Servo Motors
    • Stepper Motors
  • Systems
    • Conveyors + linear transport systems
    • Gantries + Stages
    • Rotary Tables
    • Grippers + End Effectors
    • Robotics
  • Networks
    • Connections + Sliprings
    • Fieldbuses
    • I/O
    • Sensors + Vision
  • FAQs
    • Motion Casebook
    • Motion Selection Guides
  • Suppliers
You are here: Home / FAQs + basics / FAQ: What is pullout torque and why is it a critical stepper motor value?

FAQ: What is pullout torque and why is it a critical stepper motor value?

June 8, 2015 By Zak Khan 2 Comments

Stepper motor pullout torque is the highest torque a stepper motor can output at a given speed without losing steps. Manufacturers find a stepper motor’s pullout torque by accelerating the motor up to the target speed and then increasing the torque load until the motor starts missing steps or stalling.

Performing this test operation over a range of speeds and torques lets the manufacturer plot the data in a complete torque or pullout curve. Then designers get that plot from the manufacturer when they’re evaluating different motor options.

This is a plot (courtesy MICROMO) of the pullout curve for a common stepper motor. The light-blue line contains the area of slew rate or pullout curve. The dark blue line plots the pull-in curve or start/stop region, which shows the maximum frequency at which a loaded stepper can stop and start without losing steps. The red line is mechanical power output. These plots change if there’s inertial mismatch.
This is a plot (courtesy MICROMO) of the pullout curve for a common stepper motor. The light-blue line contains the area of slew rate or pullout curve. The dark blue line plots the pull-in curve or start/stop region, which shows the maximum frequency at which a loaded stepper can stop and start without losing steps. The red line is mechanical power output. These plots change if there’s inertial mismatch.

To put it another way, the pullout-torque plot (also called slew rate) for a stepper motor shows the maximum torque at various speeds that a stepper motor can generate. If the motor runs outside of this curve, it will stall. The drive must decelerate or accelerate out and into the stepper motor’s pullout curve.

A related value is stepper motor pull-in curve — the maximum frequency at which a loaded stepper can start and stop without losing steps.) The torque-speed curve changes with inertial mismatch, so designers should aim for a 25% to 50% safety margin when sizing stepper motors. It this is impossible for the application at hand—not unusual for precision applications—other means of compensation may be in order.

To be clear, good documentation of a stepper motor includes a torque-curve that shows pull-in and pull-out curves, as well as several other factors. So before basing design specifications on a stepper motor torque curve, look for data on the following important criteria to ensure the reference is complete.

• Stepper motor characteristic plots should include the power input, because current overdraw can cause overheating. Read FAQ: Aren’t heat and noise common stepper motor problems? For more information.

• The plots should also list the drive type, as the drive influences how the motor runs. Read FAQ: What is a stepper drive and how do they work?

• The inclusion or omission of dampers influences the motors’ noise characteristics, so look for data that accounts for the effects of dampers where applicable. Read FAQ: Aren’t heat and noise common stepper motor problems?

• Stepper motor step angle relates to torque and can affect a motor’s tendency to overheat, so look for documentation that accounts for step angle. Read FAQ: What is pole count and why does it matter?

For more information, read:
Stepper Motor Speed and Torque Relationship

You may also like:

  • V/Hz Control
    FAQ: What is V/Hz control mode for AC drives?

  • Ladder logic and other PLC programming options

  • FAQ: What are other options for nanopositioning besides piezo actuators?

  • Lenz’s Law and Back EMF

  • FAQ: How do I pick torque margin to prevent stepper…

Filed Under: FAQs + basics, Motors, Stepper Motors

Reader Interactions

Leave a Reply Cancel reply

You must be logged in to post a comment.

Primary Sidebar

MOTION DESIGN GUIDES

“motion

“motion

“motion

“motion

“motion

“motion

POWER TRANSMISSION REFERENCE GUIDE

RSS Linear Motion Tips

  • Renishaw launches the FORTiS range of next-generation enclosed linear absolute encoders
  • Multi-axis motion sub-system boasts nanometer resolution
  • Anti-friction miniature linear guides from PM B.V. now come with a variety of cage options
  • How do miniature profiled rail guides compare to their full-size counterparts?
  • LINAK launches the world’s first electric linear actuator with IO-Link
Subscribe Today

RSS Featured White Papers

  • Identifying Best-Value Linear Motion Technologies
  • Learn how to reduce noise and distortion in encoders’ signals
  • Helical Planetary Gearboxes: Understanding The Tradeoffs
Tweets from https://twitter.com/Motion_Control/lists/motion-control-tweets

Footer

Motion Control Tips

DESIGN WORLD NETWORK

Design World Online
The Robot Report
Coupling Tips
Linear Motion Tips
Bearing Tips
Fastener Engineering

MOTION CONTROL TIPS

Subscribe to our newsletter
Advertise with us
Contact us
About us
Follow us on TwitterAdd us on FacebookAdd us on LinkedInAdd us on YouTubeAdd us on Instagram

Copyright © 2021 · WTWH Media LLC and its licensors. 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.

Privacy Policy | RSS