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Non-Wearing Ferrofluidic Seals
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English
Abstract
Ferrofluidic seals utilize a non-wearing “liquid O-ring” of magnetic fluid as a positive hermetic barrier. These seals have become established art and are now widely used in vacuum and nuclear systems for rotary shaft penetrations and in gas pressure systems. Leakage rate is immeasurably low (less than 10-11 std. cc/sec of helium) as measured on a mass spectrometer. The liquid seal is generally forgiving of surface finish, mechanical run-out and eccentricity. Fluids of many different physico-chemical families have been developed for operating under widely differing conditions - diesters for vacuum and wide temperature range; fluorocarbons for highly reactive environments such as chlorine, ozone, sulphur dioxide and acidic vapors; and polyphenylethers for ultra-hard vacuum and maximum radiation resistance.
They have also found wide application as exclusion seals preventing liquid, vapor, metallic and non-metallic contaminants from reaching machinery parts in applications such as digital disc drives, grinding spindles and textile wind-up heads.
New engineering developments now make these seals applicable on oil systems for gear boxes, transmissions, drives and other sealed lubrication systems where they totally contain the oil while excluding external contaminants.
This paper reviews the rapidly advancing state-of-the-art of ferrofluidic seals including sealing vacuum, gases, liquids, ultra-high speed seals, exclusion seals and sealed ferrolubricant systems (SFS).
Citation
Moskowitz, R. and Ezekiel, F., "Non-Wearing Ferrofluidic Seals," SAE Technical Paper 750851, 1975, https://doi.org/10.4271/750851.Also In
References
- Moskowitz R. “Designing with Ferromagnetic Fluids” ASME Paper 74-DE-5 1974 Mechanical Engineering February 1975
- Ezekiel F. D. “The Broad New Applications of Ferrolubricants” ASME Paper 74-DE-2 1974 Mechanical Engineering April 1975
- Moskowitz R. “Dynamic Sealing with Magnetic Fluids” ASLE paper, 74-AM-6D-2 1974
- Ezekiel F. D. “Uses of Magnetic Fluids in Bearings, Lubrication and Damping” ASME Paper 75-DE-5 1975
- Moskowitz R. “Ferrofluids: liquid magnetics” IEEE Spectrum March 1975