The ferro-magnetic fluid feedthrough is a high quality, precision engineered device. Each unit is statically and dynamically tested for vacuum integrity, pressure capacity and conformance to mechanical specifications, as part of our continuing quality assurance program.
The ferro-magnetic fluid feedthrough offers unique capabilities in the transmission of mechanical power into a chamber. It operates by trapping a low vapor pressure magnetic fluid in small annular gaps of intense magnetic fields.
A pressure differential can be maintained across each stage of trapped ferro-magnetic fluid under both static and dynamic conditions, thus creating a unique zero leakage rotary seal. There are no mechanical contact points other than the bearings, so there is nothing which will wear or require maintenance.
The ferro-magnetic fluid in this unit is designed for high vacuum service (10-8 torr). There is a wide range of ferro-magnetic fluids available for unusual service conditions.
The ferro-magnetic fluid seal uses the response of a magnetic fluid to an externally applied magnetic field. The seal has a permanent magnet, two pole pieces, a magnetically permeable, multi-staged shaft, and the ferro-magnetic fluid (see drawing). The magnetic field, completed by pole pieces and shaft, oncentrates the magnetic flux at the smallest radial gaps.
There, the ferro-magnetic fluid forms a series of liquid O-rings with gas-filled intervening regions. Each stage can typically sustain a differential pressure of 0.2 bar (155 torr) while acting in series with other stages. Individual seals, therefore, can withstand atmospheric pressure differential. These non-contaminating, highly reliable, nearly maintenance-free feedthroughs have a leak rate of less than 1 x 10-11 std CC/sec He and require no lubrication. They withstand process operation without degrading, even in demanding environments.
Applications:
Rotary stag
Barrels
Platens
Planetaries
Web coater rollers used in thin film deposition and etching processes
Specifications Table
