Linear rail systems play an indispensable role in industrial automation, machine tools, robotics, and other fields. To help users better understand, use, and maintain linear guide systems, we have compiled the most frequently asked questions, providing a comprehensive and practical reference from basic concepts to maintenance techniques.
1. What is Linear Rail System?
Linear rail systems, also known as slides, linear rails system, or linear guideways, are mechanical devices used to support and guide moving parts in a linear motion in a given direction. They are the core components of high-precision linear slides or linear guide mechanisms, and are installed on almost all types of machines.
The main characteristics of linear guides are high load capacity and torque bearing capacity, good positioning accuracy, and, due to the presence of rolling elements, a low coefficient of friction and virtually unlimited stroke. Linear guides are available in various specifications, different slider types and accessories, as well as various preload and precision grades to adapt to different application requirements.
2. What Materials are Linear Guides Made of?
Linear rail systems are assembled from guide rails, sliders, steel balls, steel ball retainers, ball return grooves, end plates, oil reservoirs, seals, screws, and nuts. Their main principle is to achieve low-friction linear motion of the slider on the guide rail by using the ball return grooves and ball retainers to make the steel balls circulate and reciprocate.
3. What is the Coefficient of Friction of a Linear Guide?
The friction in a linear guide depends on many factors besides the external load. For example, the preload level, external load, travel speed, and lubricant viscosity should be considered. Because the balls have point-to-surface contact on the raceway, the frictional resistance is very small. The coefficient of friction for lubricated linear guides is typically between u = 0.003 and 0.005. This applies to sliders without seals; sliders with seals will increase the coefficient of friction of the linear guide. Linear guides do not easily generate frictional heat or undergo thermal deformation during movement, therefore they are commonly used in high-speed linear motion systems.
4. What is the Maximum Allowable Operating Temperature?
Linear rail systems can generally operate continuously within a temperature range of -20℃ to 80℃, with an instantaneous maximum operating temperature not exceeding 100℃.
5. What is the Maximum Length of a Single Linear Guide?
The maximum length of a linear rail system is typically 4m. In reality, some manufacturers claim to offer spliced guides of unlimited length. Generally, the end faces of spliced guides are ground and marked accordingly.
6. How to Correctly Select a Linear Guide?
Priority factors for linear guide selection include: load, safety factor, lifespan, speed, load direction, application, environment, preload, and accuracy grade, etc.
7. What is Preload?
Preload, also called pre-load, is the initial load or "negative clearance" of the linear guide. This results in the rolling elements and raceway surfaces always being under constant elastic compressive force at the contact point.
To address specific application requirements, it is recommended to select an appropriate preload level based on the conditions. This will positively impact the overall operating characteristics of the linear guide system. Preload increases the stiffness of the linear guide, thereby reducing dimensional deviations under load. Preload should not exceed one-third of the load to avoid affecting the guide's lifespan. Preload adjustment is generally completed before the linear guide leaves the factory.
8. What are the Preload Levels for Linear Guides?
- Light Preload: Suitable for guide systems with low friction, minimal external influences, and extremely smooth operation.
- Medium Preload: Suitable for precision guide systems with low external loads and high overall stiffness requirements.
- Heavy Preload: Suitable for precision linear rail systems with high external loads and high overall stiffness requirements; also recommended for single-rail systems. Above-average torque loads are absorbed without significant elastic deformation. Overall stiffness is further improved only under medium torque loads.
9. What are the Possible Causes of Noise During the Operation?
If a linear rail system produces noise, it may be due to the following reasons:
- Speed exceeds the maximum allowable value;
- Insufficient installation precision;
- Inadequate interface structure;
- Interface surface structure does not meet manufacturer requirements;
- Incorrect or insufficient lubrication.
10. In Which Industries are Linear Guides Mainly Used?
Linear guides are widely used in automated production lines, material handling, robotics, injection molds, woodworking, packaging, medical, and machine tool industries.
Summary
If you encounter other special problems in practical applications, please feel free to consult our professional technicians or contact our engineering team. We will provide you with more precise solutions.
