Linear technology is a part of drive technology that focuses on linear force transmission. Linear systems consist of a series of components used to convert rotational motion into linear motion. They play a critical role in many industrial sectors where precise linear movements are required. By employing linear technology, highly accurate positioning, movements, and transfers can be achieved.
Linear technology finds applications in a variety of economic sectors, including building technology (sliding doors, sliding windows, ventilation flaps, skylights, etc.), mechanical engineering (adjustment and feed movements), handling systems (storage systems, assembly), and rail vehicles with linear motors (Transrapid, certain subways, roller coasters).
Linear Guides
Linear guides can be divided into sliding guides and rolling guides.
- Linear Sliding Guides are typically based on multiple guide elements (e.g., guide rails) or, in the simplest case – such as a wooden drawer – on a tongue-and-groove system where the tongue and groove are milled into the material
- Rolling Guides operate on the principle of rolling elements circulating between two moving guide elements. These rolling elements, like in a rolling bearing, can be balls, rollers, needles, or other rolling bodies, usually kept apart by a rolling element cage. Guides with ball-bearing rollers are also rolling-bearing guided.
Components of Linear Systems
Linear systems typically consist of multiple components that work together to enable precise linear movement. The exact composition can vary depending on the type of linear guide, but generally, a linear guide includes the following components:
- Guide Rail or Shaft
The profile rails/shafts provide the basic structure of the linear guide. They are long, precision-ground profiles/shafts made of hardened steel or aluminum. The profile rails/shafts serve as guide tracks for the carriage, ensuring low-friction movement along the linear axis. - Guide Carriage
The guide carriage or slide is the moving component of the linear guide, which slides along the profile rails/shafts. It consists of a carriage equipped with rollers or tracks, enabling precise positioning and movement along the rail. The guide carriage can vary in shape and size depending on the requirements. - Ball Recirculation Guide
In some types of linear guides, a ball recirculation guide is used to ensure low-friction movement. A ball recirculation guide consists of a ball screw and a nut filled with balls. The balls provide even load distribution and reduce friction during movement. - Rolling Elements
Rolling elements are components that roll between the profile rails and the carriage, supporting movement. Depending on the type of linear guide, these can be balls, rollers, or needle bearings. Rolling elements reduce friction and allow low-friction, precise movement along the axis. - Linear Ball Bearing/Unit
Shaft guides consist of two main components: linear ball bearings/units and the shafts themselves, which can be solid or hollow. Linear ball bearings and linear ball bearing units are thus indispensable components of shaft guides. Unlike profile rail guides, linear ball bearings/units offer the advantage of usually being compatible across different manufacturers. This allows for a wide selection of products and more flexible and quicker responsiveness in case of failures or replacement needs.
Guide Rails and Shafts
Guide rails and shafts are crucial components of linear systems that enable precise and reliable linear movements. Different types of guide rails and shafts offer solutions for various application scenarios with different requirements for load capacity, stiffness, and precision. When selecting guide rails and shafts, important properties such as load capacity, stiffness, precision, lifespan, and friction must be considered.
Types of Guide Rails
There are different types of guide rails, each with different properties suitable for various applications. The most important types are:
- Profile Rail Guides
Profile rail guides consist of a guide rail and a carriage that slides on the rail. The guide rail has a precisely profiled running surface on which the carriage moves with ball or roller bearings. Profile rail guides offer high stiffness, load capacity, and precision, and are used in a variety of applications such as CNC machines, machine tools, robotics, and handling systems. - Ball Recirculation Guides
Ball recirculation guides are specialized linear guides that enable low-friction, precise movement. They consist of a guide rail and a carriage with rows of balls. The balls run in a closed loop between the rail and the carriage, ensuring even load distribution. Ball recirculation guides offer high stiffness, load capacity, and repeatability. They are suitable for applications with high speeds and dynamic loads, such as machine tools, CNC machines, robots, and metrology. Ball recirculation guides provide high precision, smooth operation, and durability, making them ideal for applications requiring precise positioning. - Roller Guides
Roller guides consist of a series of rollers arranged in a special profile. The rollers enable low-friction movement and bear the load of the carriage or slide. Roller guides are particularly suitable for applications requiring high loads and dynamic movements. They offer high load capacity and good shock absorption. - Sliding Guides
Sliding guides consist of a guide rail and a sliding element that moves along the rail. The sliding element can be made of various materials such as plastic or metal and moves on the rail with the help of lubricants. Sliding guides provide a cost-effective solution for applications with low loads and low requirements for precision and stiffness. They are used in areas such as household appliances, office furniture, and drawer slides. - Flat and Telescopic Rails
Flat and telescopic rails are special types of guide rails developed for applications with extendable or telescopic elements. They consist of multiple interlocking sections that allow extension and retraction. Flat and telescopic rails are commonly used in drawer systems, telescopic slides, and other applications requiring extendable linear motion.
Types of Shaft Guides
Guide shafts serve as a linear guide path for the carriage or slide. They can be designed as solid or hollow shafts. The choice of the right guide shaft depends on various factors such as load, accuracy, and the environment in which the linear system operates. Some of the most common types of guide shafts are:
- Round Shafts
Round shafts are the most common type of guide shafts. They have a circular cross-section and offer good stiffness and load capacity. Round shafts are available in various diameters and lengths and can be easily integrated into linear systems. - Profile Rails
Profile rails have a rectangular or square cross-section and offer higher stiffness compared to round shafts. They are ideal for applications requiring high load capacity and stiffness. Profile rails are available in different profile geometries and dimensions and can be tailored to specific requirements. - Hollow Shafts
Hollow shafts have a hollow cross-section and offer the advantage of lower weight and better passage for cables or other components. They are commonly used in applications where weight reduction and space savings are important.
Linear Ball Bearing Unit / Linear Sliding Bearing Unit
A linear ball bearing unit is an integrated component consisting of a linear ball bearing and a guide carriage. It is often supplied as a compact unit, simplifying installation and use in linear guide systems. The linear ball bearing in the unit consists of a housing with embedded balls that roll between the rail and the guide carriage. The guide carriage is connected to the bearing housing, enabling linear movement along the guide rail. Linear ball bearing units provide low-friction and precise movement with high load capacity.
In a linear sliding bearing unit, the bearing is based on a sliding motion between a sliding element, such as a sliding bearing or a plastic bushing, and a guide rail. The sliding element allows linear movement along the guide through low-friction sliding motion. Linear sliding bearing units offer simple construction, good shock absorption, and high load capacity. They are well-suited for applications with higher loads, lower positioning accuracy requirements, and lower speeds.
Applications of Linear Technology
Linear technology is widely used in a variety of applications and industries.
Some of the main applications are:
- Machine Tools: Linear technology and linear bearings are used in machine tools for precise positioning, movements, and transfers, enabling the production of high-precision parts and assemblies.
- Automotive Industry: Linear technology is used in the automotive industry for vehicle assembly, part handling, and automated production. Linear bearings enable precise movement of robots and manufacturing equipment.
- Semiconductor Industry: Linear technology and linear bearings are used in the semiconductor industry for wafer positioning, microchip handling, and inspection of semiconductor components. Precision and positioning accuracy are crucial in this industry.
- Medical Technology: Linear technology and linear bearings are used in medical technology for the movement of medical devices, such as CT scanners, X-ray machines, and surgical robots. Precise and reliable linear movements are essential for accurate diagnosis and treatment.
- Packaging Industry: Linear technology and linear bearings are used in the packaging industry for automatic product packaging, labeling, and palletizing. Fast and precise movements are required to ensure an efficient packaging process.
Advantages and Disadvantages of Linear Technology
Linear technology offers many advantages but also has some disadvantages.
Advantages of Linear Technology:
- Precise Positioning: Linear technology enables high positioning accuracy and repeatability
- High Load Capacity: Linear bearings can handle and transmit high loads.
- Low Friction: The use of rolling elements or lubrication coatings reduces friction
- High Stiffness: Linear technology provides high stiffness to minimize unwanted movements./li>
Disadvantages of Linear Technology:
- Cost: The acquisition and maintenance costs of linear technology can be higher than alternative solutions
- Sensitivity to Contamination: Contaminants can impair the performance of linear bearings and accelerate wear
- Lubrication and Maintenance: Linear technology requires regular lubrication and maintenance to ensure optimal performance
Conclusion
Linear technology and its various types of linear bearings play a crucial role in many industrial applications where precise linear movements are required. Ball guides, roller guides, and sliding guides each offer specific advantages that should be considered depending on the application's requirements. Choosing the right type of bearing is essential to ensure optimal performance, positioning accuracy, and reliability. With careful selection, installation, and regular maintenance, companies can fully leverage the benefits of linear technology and enhance their productivity.