Linear Motion Tips

Covering Linear Motion Systems, Components and Linear Motion Resources

  • New
    • Editor’s blog
    • Industry news
    • Motion Casebook
    • Video
  • Applications
  • Slides + guides
    • Ball + roller guides
    • Cam + wheel guides
    • Crossed-roller slides
    • Linear bearings
    • Plastic + composite guides
  • Drives
    • Ball + lead + roller screws
    • Belt + chain drives for linear
    • Rack + pinion sets
  • Actuators
    • Ball + leadscrew driven
    • Belt + chain driven
    • Linear motors
    • Mini + piezo + voice coil
    • Rack + pinion driven
    • Rigid-chain actuators
  • Encoders + sensors (linear) + I/O
  • Stages + gantries
  • Suppliers

Why use integrated position measuring with linear guides?

June 7, 2016 By Danielle Collins Leave a Comment

Linear guides provide accurate, high-capacity travel for a wide variety of machine types and processes. In the most demanding applications, linear position feedback is often needed in order to ensure the tool, gripper, or workpiece follows an exact path or reaches a precise position. In these cases, design engineers can choose to add a linear encoder to the motion system, or they can use a linear guide with an integrated measuring system.

Integrated Measuring

Manufacturers offer integrated measuring systems for a wide range of both ball and roller rail systems.
Image credit: SCHNEEBERGER

How does it work?

An integrated linear measuring system is very similar to a conventional linear encoder, but with the scale mounted onto the rail and the read head mounted onto the carriage. Integrated systems are often based on magnetic or inductive encoders, rather than optical versions, because these technologies are less sensitive to dust, debris, and liquid. They are also able to tolerate some variation in gap between the sensor and the scale, which can occur if the system experiences shocks or vibrations. But with modern magnetic and inductive technologies that can provide resolution down to sub-micron levels, users aren’t sacrificing performance by choosing integrated measuring systems over optical encoders.

Integration of the measuring system covers both parts—the scale and the read head. The scale is conventionally mounted in a groove that is machined into the side of the rail. The scale is protected by a laser-welded cover, which provides a dust-tight seal and protection against water ingress (IP67 and IP68 ratings are common for integrated measuring systems).

Integrated Measuring

In the Schneeberger AMS system, the magnetic strip (2) is mounted into a ground slot (1) on the side of the rail. The strip is ground and magnetized (3), and then a protective cover (4) is welded to the rail.
Image credit: SCHNEEBERGER

The read head is typically mounted either inside or onto a housing, which sometimes also contains the encoder’s electronics. The housing is mounted onto the end of the carriage, which increases the length of the carriage, but not the width. Although this means that a slightly longer rail is needed in order to obtain the same travel distance, the lack of added width beyond the sides of the carriage means that an assembly with integrated measuring can fit in the same footprint as a standard assembly, so retrofits are generally easy, and no special provisions have to be made for added space.

Integrated Measuring

The Bosch Rexroth IMS system integrates the read head and electronics into a single housing mounted on the end of the carriage.
Image credit: Bosch Rexroth

What are my options?

Integrated measuring systems almost always come in incremental versions, regardless of manufacturer. And most suppliers also offer absolute versions, for applications where the operator needs to know the linear guide’s exact position after a power loss, or when re-homing after a power loss is not feasible. Like conventional linear measuring systems, incremental versions are provided with either analog or digital interfaces and absolute versions are commonly offered with SSI (Synchronous Serial Interface). For absolute encoders, options are also typically available for proprietary interfaces, such DRIVE-CLiQ (Siemens) or Fanuc Serial Interface.

What are the benefits?

When decision-time comes, the question may arise, “This sounds great, but I’m sure it’s more costly than buying the components separately. So why don’t I just source the components myself and get exactly what I want?” Beyond simplicity in ordering, there are several reasons to use a linear guide with integrated measuring.

First, it’s true that ten or fifteen years ago, integrated measuring systems were limited in options and compatibility. But now, with more linear guide companies offering integrated measuring systems, it’s almost guaranteed that you’ll find a system that meets even your most stringent requirements for resolution, accuracy, environmental protection, and length.

Second, with an integrated system, the hard part—mounting and alignment—is already taken care of. There’s no need for external mounting components and no alignment required.  And in the interest of simplifying logistics and inventory, both for themselves and for their customers, linear guide manufacturers have ensured that while the systems are integrated, the components are interchangeable. That means that if a rail with linear scale needs to be replaced, the user doesn’t have to also replace the read head. And if the carriage is damaged, it can be replaced while the read head and electronics remain. Schneeberger, for example uses the same reading head for all linear guide sizes.

Finally, Bosch Rexroth points out that integrated measuring systems are, or can be, ready for Industry 4.0 applications. For example, in their IMS-A measuring system, Rexroth has included additional temperature and motion sensors that can be used to monitor operating conditions and form the basis for predictive maintenance.

 

Feature image credit: SCHNEEBERGER

Filed Under: Ball + roller guides, Slides + guides (all) Tagged With: integrated measuring system, linear encoder, linear guide, profiled rail measuring

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

 

Subscribe Today

RSS Featured White Papers

  • Identifying Best-Value Linear Motion Technologies
  • What are dual-motion hybrid actuators and where do they excel?
  • Considerations for adding Linear Guide Features to Industrial equipment
Linear Motion Control Classroom

RSS Motion Control Tips

  • Motion controllers: Design from scratch or buy ready-made?
  • How are industrial shock absorbers different from other damping systems?
  • New outer-rotor brushless motor features high power density
  • High bus voltage stepper drives and motors from AutomationDirect
  • How do cycloidal gears work and where are they used?

Follow us on Twitter

Tweets by Linear_Motion
Linear Motion Tips

Design World Network

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

Linear Motion Tips

Subscribe to our newsletter
Advertise with us
Contact us
About us

Follow us on Twitter@linear_motion
Add us on FacebookDesign World Network
Add us on LinkedInLinkedIn
Add us on YouTubeYouTube
Add us on InstagramInstagram

Copyright © 2019 · 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