This is a helpful overview for people unfamiliar with linear guides (linear motion guides) and those who are considering making a selection or purchase.
What Is a Linear Guide (Linear Motion Guide)?
THK’s LM Guide Technology
THK’s Long-Refined, Widely Adopted Core Technology
THK has been cultivating its technical expertise ever since 1972, when it developed the LM Guide and other linear motion systems. Even now, that core technology continues to redefine industry standards and enables THK to satisfy an ever-growing range of needs. These systems take the rotary principles of deep-groove ball bearings, the most economical and easy-to-use rotary bearings, and apply them to linear motion components.
By using balls and rounded grooves of approximately equal diameters, THK has been able to change how the balls and grooves contact one another, moving away from point contact and closer to surface contact. As a result, THK has been able to increase a ball’s permissible load by approximately 13 times as compared to a ball of the same diameter in a traditional linear motion bearing. The service life is also extended by a factor of 2,200. (The permissible load P in the diagram is 1.3 times that of P1.)
LM Guide Variations
Many variations of the LM Guide are available to suit diverse applications. There are different categories of how loads are distributed, such as the radial load and four-way equal load types; categories based on shape, such as wide and miniature types; and more. In addition, the LM Guide featuring THK’s proprietary ball cage system helps improve equipment performance.
In addition, the product lineup also includes products that were developed from linear motion guide mechanisms, including non-linear products such as cross guides and curved guides, separate type products with two separated LM Guide units, and models with integrated gears.
LM Guide Accessories
One thing that can damage the LM block is the intrusion of foreign materials. THK offers accessories that suit a variety of conditions, including dust, cutting chips, and spatter. Foreign materials can also be prevented from entering via the rear surface of the block. Another cause of damage is insufficient lubrication, and to address this issue, THK offers lubrication devices that extend the maintenance interval for replenishing lubricant. There are also some LM Guide products available that come with an integrated linear encoder.
THK’s LM Guide Production Structure
In the belief that the optimal place to manufacture products is the location of demand, THK manufactures the LM Guide at four factories in Japan (Yamaguchi, Yamagata, Gifu, and Mie) in addition to production facilities around the world.
THK also creates products with unique specifications in addition to the lineup available in the catalog. Let us know if the items in the catalog do not meet your needs, and we will investigate options for you.
The LM Guide does not move on its own and requires some kind of power source. It can be moved by hand, but it is intended to be moved through mechanical means. Combining the LM Guide with a ball screw or another drive component will enable it to move the desired object easily and smoothly. In addition to single LM Guide units, THK also manufactures actuators that combine an LM Guide with a drive element.
OMNIedge: IoT-Enabled Predictive Failure Detection
OMNIedge is THK’s IoT service for manufacturing. This service eliminates the time and money it takes to select a sensor, develop an algorithm, and set up a network environment so it can be used right away. It is currently available not only for the LM Guide, but ball screws and actuators as well.
LM Guide General Catalog
Please refer to the General Catalog for the selection, dimensional drawing, dimensional table, model number configuration, etc. of the LM Guide.
View the LM Guide General Catalog in the THK Catalog Center
Basic LM Guide Selection Method
Based on your application and usage conditions, temporarily select a general model type and size. From there, we calculate the applied load, equivalent load, and static safety factor. If the static safety factor meets the requirement, we calculate the average load and nominal life to determine if it meets the desired service life.
Optimal Product Selection Tool for the LM Guide
Inputting the usage conditions into this tool will help you select the ideal product for standard model types. An easy selection mode is available to confirm a rough calculation, and once the model is chosen, a detailed selection mode is available for service life calculations and more.
Sign up to use the optimal product selection tool
RoHS Directive and Other Environmental Activities
THK has established and manages the THK Group Green Procurement Guidelines to reflect the more stringent laws and regulations enacted in Europe and other regions as well as the requirement to manage the entire supply chain.
See the EU RoHS-Compliant Parts List for information about THK's compliance with the EU RoHS directive (regarding the 10 substances in Directive 2015/863/EU).
For inquiries about THK’s compliance with other environmental laws and regulations, please contact your THK sales representative or distributor.
Design, Selection, and Technical FAQ
Service Life Calculator
A special feature where the LM Guide excels against other linear guide products is that the service life can be predicted. The THK Technical Support Site allows you to perform an easy online calculation of the product life that corresponds to the configuration of your device. Up to 10 calculation results can be saved and exported as a PDF. It is also easy to pull up results and recalculate them.
Sign up to use the service life calculator
CAD files are essential to machine design. The THK Technical Support Site provides CAD downloads in a variety of formats, including DXF, STEP, IGES, and Parasolid. DFX files come in 2004 and later versions. Image formats such as JPEG and PNG are also available for use in documents.
Sign up to download CAD files
See the instruction manual for how to perform installation, lubrication, and general maintenance.
View the LM Guide instruction manual in the THK Catalog Center
You can view over 500 questions and answers related to engineering, design, troubleshooting, and more. They are organized by product group, or you can search the FAQ. See some example questions and answers
The THK Technical Support Site
The THK Technical Support Site is a free-to-use service where designers of industrial machinery and robots or other users can register as members to access CAD files and online tools that are useful for selecting the optimal product model and calculating the service life. This website also allows users to request quotes and export parameter sheets. Simply sign up as a member and gain access to a variety of free services.
Sign up for the Technical Support Site
Mounting Methods and Maintenance
There are two main steps to mounting an LM Guide.
- Mounting the LM rail
- Mounting the LM block
The most common configuration is a two-axis layout. There are several ways the second (subsidiary) axis can be set up.
- Using a straightedge
- Using the parallelism of the table
- Having the subsidiary LM rail follow the master LM rail
- Using a jig
Lubrication is crucial for the proper functioning of the LM Guide.
The THK Technical Support Site features the following documents, which are intended to help extend the service life of the LM Guide.
Technical information: LM Guide inspection tips to extend the service life
Technical information: Signs an LM Guide needs replacement
* To access the Technical Support Site, you must create a free account or log in.
The LM Guide’s performance can be maximized by using the right lubricant based on the application and purpose.
Lubricant can be split into the following general categories.
- Grease lubricant
- Oil lubricant
Each of these types of lubricant have their own special characteristics.
You can download the SDS (Safety Data Sheet) for the grease used to lubricate a product from the Technical Support Site.
* To access the Technical Support Site, you must create a free account or log in.
THK CO., LTD.
2-12-10 Shibaura, Minato-ku, Tokyo 108-8506