1. Enables Very High Rotor Speeds
Rotors supported by magnetic bearings can operate in supercritical conditions at speeds reaching hundreds of thousands of revolutions per minute (RPM), with the maximum peripheral speed limited only by the strength of the rotor material. For a given journal diameter, a rotor supported by magnetic bearings can typically achieve speeds approximately twice as high as one supported by rolling-element bearings, and three times as high as one supported by hydrodynamic (sliding) bearings.
2. Low Frictional Power Loss
At a rotational speed of 10,000 RPM, the power loss of a magnetic bearing is only about 6% of that of a hydrodynamic bearing and 17% of that of a rolling-element bearing.
3. Low Maintenance Costs and Long Service Life
Because magnetic bearings use magnetic forces to suspend the journal, there is no physical contact between the relatively moving surfaces. Consequently, issues such as friction, wear, and contact fatigue—which typically limit the lifespan of mechanical bearings—do not exist. Furthermore, since electronic components are significantly more reliable than mechanical parts under rated operating conditions, magnetic bearings offer superior service life and reliability compared to traditional bearings.
4. No Lubrication Required
There is no risk of environmental contamination from lubricants. Magnetic bearings offer an unparalleled advantage in applications such as vacuum environments, ultra-clean/sterile rooms, or processes where lubricant contamination is strictly prohibited. In general industrial applications, they also provide a competitive edge in terms of cost and space requirements, as they eliminate the need for auxiliary systems for lubricant storage, filtration, cooling, and circulation.
Oil-free magnetic-bearing centrifugal compressors and blowers represent the primary applications of magnetic-bearing technology in the field of air compression.
Currently, very few domestic (Chinese) companies are involved in the production of oil-free centrifugal compressors for standard pressure ranges, primarily due to a persistent technological gap.
International brands remain at the forefront of this sector; for example, CompAir introduced its "Quantima" magnetic-bearing, variable-frequency centrifugal compressor in 2010, which covers a pressure range of 3–8 bar and a flow rate range of 28–70 m³/min. Currently, air compressor companies in the domestic market—including Atlas Copco—have launched magnetic-bearing single-stage centrifugal blowers, targeting the market segment currently dominated by a large number of Roots-type blowers.
While the design of impellers and other components for single-stage centrifugal blowers has reached a high level of maturity domestically, the magnetic-bearing system—which represents the core technical challenge—remains the most difficult aspect. Most of the magnetic-bearing centrifugal blowers introduced by domestic air compressor companies are merely rebranded or assembled units, with the underlying technology largely sourced from the South Korean firm SeAH.
Interestingly, the localization of magnetic-bearing technology has not emerged from within the air compressor industry itself, but rather from outside of it. Notable domestic players with proprietary magnetic-bearing technology include Tianjin Yisheng, Zhejiang Feixuan, and Nanjing Magvalley, with technical roots tracing back to institutions such as Tsinghua University and Southwest Jiaotong University.
In reality, however, blowers have traditionally belonged to the same niche sector as pumps—a field that differs significantly from the air compressor industry in terms of sales channels and business models.