The static seal advantage for vacuum stirring
A primary challenge in vacuum processing is introducing rotary motion without compromising the chamber's integrity. Traditional mechanical seals present leakage risks. The dual axle ferrofluid vacuum feedthrough addresses this by replacing dynamic seals with a static sealing structure. According to patent analysis, this approach uses magnetic coupling to drive a reactor's rotating shaft. It transmits kinetic energy without contact, isolating the drive mechanism from the material working chamber. This structure is reported to completely solve leakage problems associated with mechanical dynamic seals and packing seals.
Design and operational principles
These feedthroughs utilize multiple rings of ferrofluid contained in stages. The stages are formed by grooves machined into either the shaft or the pole pieces. Permanent magnets generate the field that contains the fluid. This non-contact sealing method helps reduce wear and particle generation, which is important for maintaining clean vacuum environments. With the use of permanent magnets, the operating life and equipment maintenance cycles are generally very long. The technology has been developed for over 30 years and is widely used in vacuum systems for semiconductor and FPD industries.
Performance and application scope
The sealing interface in these systems can be designed with a relatively small contact load. Industry sources indicate it can be just 25-50% of the load seen in ordinary spring-loaded face seals. This contributes to reliable operation under demanding conditions. The devices are capable of supporting processes involving high temperatures, high vacuum, and high rotational speeds. They are suited for handling flammable, explosive, or toxic media, making them applicable in pharmaceutical, fine chemical, and microbial engineering operations. However, a known limitation exists. Magnetic liquid seals are generally limited to sealing gases and vapors, not direct pressurized liquid, due to premature seal failure. Research was underway in 2020 to try and solve this problem.
We manufacture these dual axle feedthroughs and related components for vacuum system integrators.