Ferrofluidic Solutions

Magnetic, or ferrofluidic, seals use a magnetic field to create an ideal method for transferring rotational motion into vacuum or pressurized environments.  Less friction results in high reliability, longer life, and offer an efficient, cost-effective seal solution.   They effectively handle high torque transmission, have high speed capability, low drag torque, and smooth motion at low speeds and during start-up.  

Ferrofluid seals are used in rotary gas unions & reactive gas seals in vacuum manufacturing applications, as acoustical dampers, and in CVD furnaces and sputtering systems.  They’re common in aerospace, semiconductor & solar manufacturing, vacuum coatings and other industries.

S & D Materials has designed, sold and repaired ferrofluidic solutions for over a decade, including seals in feedthroughs, rotary gas unions and host assemblies of all types.  We perform both minor repairs and major overhauls.  We also support dozens of new and refurbished seals for semi manufacturing tools from Novellus, Axcelis, AMAT, TEL and Varian.

Ferrofluidic Solutions

Features & Benefits

  • Why a Ferrofluidic Seal

    Performance

    • Better seal - True hermetic seal formed under dynamic & static conditions; magnetic forces compel the ferrofluid to seal completely so no gas can enter or escape.
    • More efficient operation –   Through-shaft construction allows optimal torque transmission, inhibits backlash, slippage during in-phase rotation.
    • High speed operation: The hermetic seal remains intact at rotational speeds up to 15,000 - 20,000 RPM and higher for a 1" shaft.

    Lifetime

    • Long life - Ferrofluid seals function longer because the sealing medium is fluid, thus no friction
    • Low impact operation - No deterioration from repetitive compress-relax cycles or plasticizing effects between activity
    • High reliability - Performance levels maintained after extended time in operation. The sealing medium is fluid, so, again there is no friction. 

    Environmental Impact 

    • Leak-free performance - Fluid will not leak from a ferrofluid seal; fluid loss is only from evaporation at high temperatures.
    • Non-contaminating - With intrinsically low vapor pressure, ferrofluids hold seal integrity even in vacuums in the 10-9 mbar range; absence of mechanical friction means no risk of particulate invasion harmful to the system.
  • Why S & D Materials
    • Lowest pricing – Lower costs through streamlined operation and high volume enable pricing well below other ferrofluidic solution providers  
    • US Based supplier – Over 10 years providing ferrofluidic seal solutions to industry, government and institutions
    • Fast turnaround – Most repairs are completed within 2-3 weeks from receipt of unit
    • OEM original components – bearings, magnets, hardware, ferrofluid 
    • Ferro fluid available for sale   

Specifications & Data

Step Description
SYMPTOM Low magnetic fluid level
Loss of vacuum pressure
Motion issues - rotational, linear
Slippage, backlash
Discoloration of surfaces - shaft, bellows, housing
INSPECT & EVALUATE Inside surface of hollow shaft / outside surface of solid shaft
Initial rotational check
Inside surfaces during disassembly
Assess damage to parts, bearings, magnetic fluid
REPAIR / REPLACE COMPONENTS Shaft, hollow / solid
Pole pieces & magnet
Bearings
O-rings, snap-rings
Bellows
Grease
Magnetic fluid
SERVICES PERFORMED AS NEEDED Hollow shaft, housing - clean & repolish
Pole pieces - clean & repolish
Replace any missing bearings
Remagnetize magnetic fields
Refill, replace, 'top off' magnetic fluid
TESTING / QC Rotational and linear motion check
Visual inspection
Images recorded of work performed
He leak check, at rest and in operation
  • Magnetic seals need to be installed vertically or horizontally as appropriate; the incorrect configuration risks damaging components such as bearings due to load imbalance
  • Improper installation can also lead to interior component damage, resulting in shortened lifetime.
  • Organic solvents such as alcohol, acetone, water, oil should not flow into the seal when cleaning any surfaces. Solvent misuse can be a primary cause of weakened sealing capacity.
  • Magnetic seal lifetime can be impacted by the magnetic fluid useful life, which can itself be affected by high temperatures. In applications with high process temperature and high rotational speeds, the product should be water-cooled with specific flow rates.
  • Vacuum pressure can rise instantaneously when the rotating shaft is subject to long periods of inactivity; this is normal and normal levels should return after several turns of the shaft.
  • Pressure inside a typical magnetic seal should be specified and maintained.

If applications involve higher than intended temperatures or pressures, high frequency waves, high loads or strong magnetic fields in the presence of particulate materials, the manufacturer should be consulted.

Base Application / Uses Magnetization
mT
Viscosity
20 0C
Water General test 32 21
Iso - Paraffin General test 33 180
Alkylnaphthalene Dust seal
Vacuum seal
34
40
50
60
280
370
600
1300
Perfluoro-polyether (PFPE) Heat, solvent, oxidation & radiation resistance; Vacuum seal 40
40
2800
3500
Poly-alpha-olefin Acoustic dampers 11
11
22
22
22
22
22
1000
2000
500
1000
2000
4000
5000

Applications and Industries

Ferrofluidic Solution Application / Use Industry / Market
Leak Free Rotating Systems Wafer chucks
Manifolds
Electro-optic instruments
Robotics
Semiconductor Mfg., Photovoltaics, Coating
Vacuum Feedthrough Vacuum coating systems
Silicon crystal growth
Thin film coating
Photovoltaics, Semiconductor Mfg., Defense & Aerospace
Rotary Gas Union Vacuum deposition systems
Gas handling
Chemical Vapor deposition
Semiconductor Mfg, Optics, Lighting, Defense & Aerospace, Medical, Electronics
Reactive Gas Seal MOCVD
LPCVD
PECVD
Defense & Aerospace, Power & Energy, Semiconductor Mfg, Consumer Technology
Spindle Wafer movement
Precision MEMS
Electronics, Power & Energy, Technology, Medical, Defense
Acoustic Damper Motion and Vibration Absorption
Optical Scanner
Robotics
Plotters
Semiconductor Mfg., Manufacturing, Opto-electronics

Contact Info

S&D Materials, LLC.
39 South Main Street Suite 222
Rochester, NH, 03867 USA

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