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Linear Rails and Blocks Guide

The purpose of this guide is to be a comprehensive resource on linear guides.

    Linear Rails and Blocks Guide Overview
  • Detailed Technical Information
  • List Of Suppliers
  • Price Comparisons
  • Video Tutorials
If you would like to contribute to this guide, please email us using the contact us section of this website. We value your comments!


Linear Guide Overview


Linear Guides are a block and rail system that helps support the motion of an application.

How Linear Guides Work


There are two parts to the Linear Guide System: the Linear Block and the Linear Rail. The linear block moves along the linear rail along the plane the rail is positioned for. The block moves forward and backward along the straight linear rail. Linear blocks connect to the moving components by mounting to the block to support the motion for the specified component. The motion is created along the rail through recirculating ball bearings within the block that is contacted on the rail.

Basic Types of Linear Guides


Two basic types of linear guides are predominantly used in industry today. These types are: Sliding contact linear motion bearing and rolling element linear motion bearing guides. The main distinction between the two is how the motion of the linear block occurs along the linear rail.

Sliding Contact

The sliding contact is known as the oldest type of linear guide used within industry. This may be because of its simplicity and inexpensiveness in manufacturing that companies still use this "old technology". A huge draw back with the sliding contact is its high coefficient of friction compared to its other types. With such a high coefficient of friction it becomes difficult for companies to use this type of guide for applications with high precision or high speed. Because of this huge set back it is thus hard to predict and design for an exact lifetime for the linear guides.

Rolling Element

This type of linear guide is known to be the most commonly used type for most applications. Ball bearings or rollers are elements usually used within these blocks to create the rolling motion of the block. The coefficient of friction is therefore already decreased from the original sliding contact block just because of the rolling action. These types of blocks are easier to control increasing accuracy, precision, speed for the guide. There is a wide variety of options to customize this block, making it a better choice over the sliding contact block.

Applications that use Linear Guides


Linear guides are used to move a machine table in either the X or Y direction. Applications which require high precision use linear guides due to their high accuracy and precision capabilities.


In the application below, each table uses linear guides for positioning. Machine tool applications use linear guides because of their ability to manage temperature rise and high speed changes.


Linear guides are used to transport heavy product with ease.


In this application, the Linear guides were used to help create the motion of a robot pick-and-place machine.

Select a Linear Guide


When selecting a linear guide there are a few factors that should be considered for your application. Following this flow chart will help guide you in choosing the optimum linear guide for your needs,
The first step in really understanding the application you are using the linear guide for. Different applications call for different customizations, whether it is in the environment you are working with or the machinery the guide will be supporting. For example, if the linear guide will be used for a small application, the preload and accuracy may want to be increased for more precise motion.
Linear guides range in many different sizes. Some companies manufacturing a miniature series of linear guides as small as a 3mm small rail width to as big as a 63mm rail width! The factors that go into choosing your size are space for your application and load capacity. Each block and rail is rated for a particular dynamic and static load capacity, therefore knowing how much load the block will undergo is imperative for linear guide selection. Calculating this incorrectly could run the risk of failure in the rail of the system.



Note 1: There might be limitations on the mounting space of the linear guide because of structural restrictions on the machine.
Note 2: In the case of a ball screw drive, it is advisable to choose a linear guide with it’s model number the same, as or closest to the ball screw shaft diameter.
Note 3: Applied load per ball slide herein shall be calculated simply by dividing total applied load by the number of ball slides.

Advantages/Disadvantages of a Linear Guide



Troubleshooting a Linear Guide


There are a few things to look for in your linear guide that want to avoid. Regularly machinery such as corrosion of the rail, indentations in the rail, or wear can occur within the linear guide. These different damages can occur because of poor care of the system, excessive misalignment, contaminating the rail with the wrong product, or poor lubrication. An easy way to troubleshoot these types of problems is to always clean and care for the blocks and the rails, and make sure the installation is followed as stated in the manuals.

The Cost of Linear Guides


The cost of linear guides is dependent upon size and material of the linear guides. For applications with higher load capacity, you will generally need a bigger linear block. In this case the wider the block or the longer the rail needed will increase the price of the linear guide. For more specific pricing inquiries please contact the factory to assist you in pricing.

Required Maintenance for a Linear Guide


Most linear guides are equipped with a lubrication mechanism within the block. This is a great advantage because it essentially decreases the maintenance required for the user of linear guide. The main requirement is to just refill the grease lubrication when needed and the block will have a longer lifetime. Although the lubrication does help decrease maintenance, linear guides still need to be dusted and cleaned from unwanted debris that would cause the linear guide to deteriorate.

Environmental Aspects for a Linear Guide


The environment of a linear guide in use is dependent upon the application of the linear guide. Certain precautions should be taken for different environments. Linear Guides should have a clean, debris free environment because of it’s re-circulating rolling elements. These rolling elements may lose its lubrication when interfering with dirt on the rail. Although a clean environment cannot be sustained in some applications at all times, an upgraded lubrication option can be added to a linear guide to help increase lifetime of the guide in a more dirty environment.

Linear Guide Invention & Evolution


The invention of the linear guide occurred in 1932 when it was patented by a company based out of France. Steel was the first type of material used in the rolling elements because of its accurate and smooth linear movement. However, while this may be true, a US company named Thomson first commercialized the rolling element in their ball screws with the first recirculation ball type in the year 1946. Years following, companies have been innovating and evolving the linear guide into the product it is today.

Linear Guide Glossary


Accuracy
Based on the running accuracy of ball slides that travel on the rails, the required motion accuracy is expressed in a particular accuracy grade, like P5 or PN.

Applied Loads
These are the loads applied to the linear guides, which usually consist of self-weight of a table, weight of transported objects, and/or forces that are working on a machine tool. The loads are normally applied vertically or laterally against motion axis.


Application
This is the information on the type of machine (application) like machine tools, transporting systems, or measurement apparatuses for which linear guides are to be used. Generally, such information is very useful to select the appropriate linear guides

Ball Bearings
Steel circular balls that create the motion for the linear guide system through its re-circulation.

Dynamic Load Capacity
The amount of force the linear guide can withstand when the block is in motion.

Grease
The class of lubricants applied to smooth the movement of guides and moving parts of the ball screw. Grease forms an oil film on metal surface to reduce wear and friction, thereby prolonging the life and preventing rust. Linear slides require periodic maintenance of grease according to their use conditions.

Linear Guide Block
The block that moves along the track that supports the machine or application it is holding. It houses the lubrication and the re-circulating bearings within the block.

Linear Guide Rail
The track that the block moves on, made of carbon steel. This track is a uniaxial track, meaning it travels only along one axis.

Load Moment
When the load acting upon the table extends beyond the table in the longitudinal, lateral or vertical direction, the linear slide receives a torsional force.

Machine Structure
This information covers the structure of machines and their relevant aspects of construction such as dimensions around the place where linear guides are mounted to, positions and directions of external forces, etc. This is compulsory information for selecting particular linear guides.

Pitch
The hole-to-hole distances found on the linear rails.

Required Life
Required life is expressed in a total travel distance (For example, 5000 km).

Service Life
The calculated time the linear guide can withstand before failure in hours.

Speed
This means a relative speed of the table (with the ball slides) against the rails. It is expressed as, for example, 100 m/min.

Static Load Capacity
The amount of force the linear guide can withstand when the block is not moving.

Stroke
This means a travel distance that a table mounted on ball slides is required to make.


Lifetime for a Linear Guide



Popular Linear Guide Suppliers


Anaheim Automation
Chieftek
Hiwin
IKO
NB
NSK
SFK
TBI
THK

Companies With Online Pricing For Linear Guides


Anaheim Automation

Websites With Linear Guide Information


ABBA
Anaheim Automation
Chieftek
Del-Tron
Gilman
HIWIN
IKO
INA
LinTech
NB
Ozak
PBC
Rockford Linear Motion
Rollon
SBC
SKF
STAF
TBI
Thomson
THK

Price Comparison


Here is a price comparison for what a Size 15mm rail and block with a length of 500mm (20 inches) would cost from different suppliers.

Anaheim Automation (Data from April 2014)
Total Cost: $81.00
Block part number is TBI-TRS15VS-N-Z0 with a price of $29, Rail part number is TBI-TR15N-0500-10-10 with a price of $52.
Both items were shown to be in stock with an online shopping cart to purchase.


Less Popular Linear Guide Suppliers


ABBA

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