The success of modern technology, from the delicate layering of a 3D printer to the continuous, heavy-duty operation of massive factory automation systems, fundamentally depends on precise, repeatable motion.
Linear Guides are a block and rail system that helps support the motion of an application. The linear guide blocks move down the length of the linear rail along the plane it was positioned for.
In this guide, we'll strip away the complexity to reveal the ABCs of linear guides, introducing the main types of linear guides, including HG, EG, QH, QE, RG, MG series, and so on.
The HIWIN HG series linear guideways are optimized for strength, utilizing a circular-arc groove design that provides superior rigidity and load capacity compared to similar products. Because the design allows for equal load ratings in all radial and lateral directions, and includes a self-aligning feature to absorb installation error, the HG series ensures guaranteed high accuracy, smooth operation, and extended service life, even at high speeds.
The HG series is designed for hassle-free mounting. Its unique circular-arc groove, featuring 45-degree contact points, gives the guide an inherent self-aligning capability. This means the system can automatically absorb most surface irregularities and installation errors through the elastic shifting of the rolling elements. The result is an easy installation process that still delivers guaranteed high accuracy and incredibly smooth linear motion.
Due to precision dimensional control during manufacturing, the HG series maintains a tight tolerance range that enables total interchangeability. This critical feature means any block can be freely paired with any rail of the same series while retaining dimensional accuracy, greatly simplifying inventory and replacement needs. Additionally, a ball retainer is integrated into the block to ensure the steel balls remain securely in place when the carriage is removed from the rail for maintenance.
The HG series is engineered with a robust four-row design, allowing it to offer equal load ratings in all directions—radial, reverse radial, and lateral. Furthermore, the specialized circular-arc groove maximizes the contact width between the rolling elements and the raceway. This design choice is what directly enables the system to handle large permissible loads while maintaining exceptionally high rigidity.
Square Types
Flange Types
The HG series offers five accuracy classes: Normal (C), High (H), Precision (P), Super Precision (SP), and Ultra Precision (UP). Select the appropriate class based on the accuracy requirements of your equipment.
Each guideway can be preloaded using oversized balls. Typically, a linear motion guideway features a slight negative clearance between the grooves and balls to enhance stiffness and maintain high precision. As shown in the figure, applying preload increases the load capacity, doubles rigidity, and cuts deflection in half. For models smaller than HG20, it is recommended to keep the preload no greater than ZA to prevent excessive preload that could shorten the guideway’s service life.
|
Class |
Code |
Preload |
Condition |
Examples of Application |
|
Light Preload |
Z0 |
0-0.02C |
Certain load direction, low impact, low precision required |
Transportation devices, auto-packing machines, X-Y axis for general industrial machines, welding machines, welders |
|
Medium Preload |
ZA |
0.05C-0.07C |
High precision required |
Machining centers, Z axis for general industrial, machines, EDM, NC lathes, Precision X-Y tables, measuring equipment |
|
Heavy Preload |
ZB |
0.10C-0.12C |
High rigidity required, with vibration and impact |
Machining centers, grinding machines, NC lathes, horizontal and vertical milling machines, Z axis of machine tools, Heavy cutting machines |
Note: The “C” in the preload column denotes basic dynamic load rating.
The EG series is designed with a low profile while providing high load capacity and rigidity. It delivers equal load ratings in all four directions and features a self-aligning capability that compensates for installation errors, ensuring greater accuracy. Its reduced assembly height and compact length make it ideal for high-speed automated machinery and applications with limited space. The ball retainer is engineered to keep the balls securely in place even when the block is removed from the rail.
Square Types
Flange Types
The accuracy of the EG series can be classified into normal (C), high (H), precision (P), super precision (SP), ultra precision (UP), five classes. Please choose the class by referring the accuracy of applied equipment.
A preload can be applied to each guideway. Generally, a linear motion guideway has a negative clearance between the groove and balls in order to improve stiffness and maintain high precision. The figure shows that adding a preload can improve stiffness of the linear guideway. A preload no greater than ZA would be recommended for model sizes smaller than EG20. This will avoid an over-loaded condition that would affect guideway life.
|
Class |
Code |
Preload |
Condition |
|
Very Light Preload |
Z0 |
0-0.02C |
Certain load direction, low impact, low precision requirement |
|
Light Preload |
ZA |
0.03C-0.05C |
low load and high precision requirement |
|
Medium Preload |
ZB |
0.06C-0.08C |
High rigidity required, with vibration and impact |
Note: The “C” in the preload column denotes basic dynamic load rating.
The WE series provides equal load ratings in the radial, reverse radial, and lateral directions, with 45-degree contact points. Its wide rail design enables the guideway to support high loads, moments, and rigidity. The self-aligning structure compensates for most installation errors, ensuring high accuracy. With its low profile, low center of gravity, and the option to use a single rail, the WE series is ideal for applications with limited space or where high moment capacity is needed.
Square Types
Flange Types
The accuracy of the WE series can be classified into normal (C), high (H), precision (P), super precision (SP), ultra precision (UP), five classes. Please choose the class by referring the accuracy of applied equipment.
Each guideway can be preloaded to enhance performance. Typically, a linear motion guideway features a slight negative clearance between the groove and the balls to increase stiffness and maintain high precision. As illustrated, applying preload further enhances the rigidity of the linear guideway.
|
Class |
Code |
Preload |
Condition |
|
Very Light Preload |
Z0 |
0-0.02C |
Certain load direction, low impact, low precision requirement |
|
Light Preload |
ZA |
0.03C-0.05C |
low load and high precision requirement |
|
Medium Preload |
ZB |
0.06C-0.08C |
High rigidity requirement, with vibration and impact |
Note: The “C” in the preload column denotes basic dynamic load rating.
Square Types
Wide Types
The accuracy of the MG series can be classified into normal (C), high (H), precision (P). Please choose the class by referring the accuracy of applied equipment.
|
Class |
Code |
Preload |
Accuracy |
|
Light Clearance |
ZF |
Clearance 4-10μm |
C |
|
Very Light Preload |
Z0 |
Clearance 0-3μm |
C-P |
|
Light Preload |
Z1 |
0.02C |
C-P |
Note: The “C” in the preload column denotes basic dynamic load rating.
This guide introduces linear guides used in modern automation systems to achieve precise and repeatable motion, focusing on comparing the main series—HG, EG, WE, and MG. Explore the full range of linear guides at lily bearing and find the perfect solution for your automation needs today.
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