TOP > Rotary Feedthrough > What is a Magnetic Seal? Magnetic Circuit Configuration unique to Rigaku

What is a Magnetic Seal? 
Magnetic Circuit Configuration unique to Rigaku

What is a Magnetic Seal?

Rigaku has begun producing Rotary Feedthroughs since 1978, when our Company designed and developed a Rotary Feedthrough as a shaft seal for the X-ray generator with rotating anode*1 of an X-ray diffractometer*2.
The Rotary Feedthrough which is used for the x-ray diffractometer operated at severe conditions such as high-speed rotation and high vacuum.
The larger the X-ray output of diffractometer was, the severer operating conditions for the Rotary Feedthrough was.

By developing a unique magnetic-circuit structure, Rigaku succeeded in creating a Rotary Feedthrough that could withstand these severe operating conditions.
Today the Rotary Feedthrough of Rigaku is loved by the brand name of "the magnetic seal".
And it is broadly used in the field of advanced technology such as semiconductor manufacturing equipment.

*1:X-ray generator with rotating anode :The component in the X-ray diffractometer that generates the X-rays.
To generate the X-rays, the electrons emitted from cathode crash into the anode which rotates at high speed in a vacuum.
*2:X-ray diffractometer :A analysis equipment used in a wide variety of fields, including R&D, semiconductors, medicine, criminal investigations and pollution analysis.
It is used to determine the identity of crystalline solids based on their atomic structure.


Rotating anode for X-ray generator


Magnetic Circuit Configuration unique to Rigaku

Rigaku Magnetic Seals form powerful magnetic fields repelled each other by arranging the same pole of the magnets on both sides of a pole piece(NS-SN-NS).
The tip of the pole piece inserted in this strong magnetic field is split in two, creating a independent magnetic circuit.
The repulsion effect between the two adjacent magnetic fields focuses the magnetic flux on the tips of the pole piece to hold the magnetic fluid firmly in place.
This arrangement enables each stage of the seal to withstand even large pressure differentials.
As a result, the Magnetic Seal can be made compactly.
With this magnetic-circuit structure's ability to withstand even large pressure gradients, the gap between the pole piece and shaft can be quite large.
For the same reason, the magnetic seal can design the product of a high speed rotation or a large diameter shaft.
Additionally, the magnetic circuit is housed entirely within the pole piece. This structure offers the advantages of minimizing magnetic flux leakage from the magnetic seal and protecting the magnetic field from influence from external magnetic fields.
As a result, Rigaku Magnetic Seals are relied on applications both in equipment that must be shielded from external magnetic fields (such as those from electron-beam lithography system) and in equipment on which strong magnetic fields are applied (such as large diameter silicon growth system).


Magnetic Circuit Configuration unique to Rigaku


Technical data

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