Use of magnetic bearings
Twin Screw Barrel,Barrel Screw Extruder,Injection Molding Barrel,Barrel And Screw Zhoushan Jinsheng Bimetallic Plastic Machinery Factory , https://www.jinshenggalloy.com
October 02 01:07:31, 2025
Magnetic bearings are a type of support system that uses magnetic forces to suspend or carry the load of a rotor. These bearings have experienced rapid development in recent years, especially in high-speed, low-friction, high (or low) temperature, and vacuum environments. Compared to traditional bearing systems, magnetic bearings offer several advantages, such as high precision, safe operation, and reliability. They also have great potential for future applications.
### Characteristics and Classification
1. **Features**
- Non-contact operation reduces wear and tear.
- High accuracy and stability during operation.
- Capable of functioning in extreme environments like high temperatures, deep cold, and vacuum conditions.
- May cause electromagnetic interference, but they do not produce other forms of pollution.
2. **Classification**
Magnetic bearings can be categorized based on control methods, magnetic field types, and structural layouts. Common classifications include:
- **Permanent magnet type**: Passive or forced, but not stable in all three directions without active components.
- **Electromagnet type**: Requires power and is usually active.
- **Hybrid type**: Combines permanent magnets and electromagnets.
- **Suction vs. Repulsion type**: Suction bearings are more commonly used due to higher efficiency.
- **Superconducting bearings**: Divided into low-temperature and high-temperature superconducting types.
It's important to note that each type has specific constraints and limitations. For example, pure electromagnet bearings require complex control systems and consume more power, while repulsion-type bearings are less efficient and rarely used.
### Typical Magnetic Bearings
1. **Permanent Magnet Bearings**
These bearings use permanent magnets to provide support. Their performance depends on the magnet material, shape, pole area, thickness, and the design of soft magnetic steel. Theoretical calculations can be complex, so many engineers rely on experimental testing to determine optimal configurations. Permanent magnet bearings cannot be oversized, as they may fail to support their own weight if the scale is too large.
2. **Active Magnetic Bearings (AMB)**
These bearings use electromagnets controlled by feedback systems to maintain the rotor's position. They are often used in high-precision applications, such as machine tool spindles, where radial and axial movements must be precisely controlled.
### Applications of Magnetic Bearings
Although still under research, magnetic bearings are being tested in various fields:
1. **Machine Tools**
- France’s S2M company developed a 5-degree-of-freedom magnetic bearing spindle with a radial dn value of 4×10ⶠmm·rpm and a journal speed of 200 m/s.
- A super-precision lathe using automatic magnetic bearings achieves 2000 rpm and 0.05 µm precision.
2. **Precision Instruments**
- The UK National Physical Laboratory uses magnetic floating guide rails in an automatic resolution measuring instrument, achieving a stiffness of 175 N/mm and a resolution of 0.11 nm at 1 kHz.
3. **Pumps**
- A magnetic bearing blood pump developed by the University of Tokyo and NTN supports a radial load of 18 N and a thrust load of 9.2 N.
- France’s SEP company uses S2M’s magnetic bearings in liquid oxygen and hydrogen pumps for rocket engines.
4. **Space Technology**
- Japanese companies like NAL & MELCO and NAL & TOSIBA use magnetic bearings in inertia wheels for spacecraft attitude control.
5. **Physics Experiments**
- Germany’s Uranit introduced particle beam converters using magnetic bearings for high-precision applications.
- A neutron selector from KFA uses a single-degree-of-freedom magnetic bearing, operating at 36,000 rpm.
### Conclusion
Magnetic bearings represent a promising technology with wide-ranging applications in advanced engineering. While still in the experimental phase, their ability to operate in extreme conditions, reduce mechanical wear, and improve system efficiency makes them a valuable innovation for the future. As research progresses, we can expect more commercial applications and widespread adoption across industries.