Ferrofluid Rotary Vacuum Feedthroughs
Leak-tight rotary motion into high and ultra-high vacuum, with no rubbing O-rings to wear, leak or shed particles. High quality, lower cost, and a drop-in match for the major brands.
Already using another brand? Find your Apex equivalent.
Our cross reference chart below maps Lesker, Ferrotec and Rigaku part numbers to the matching Apex Vacuum model, so you can replace like-for-like at a lower cost. Can't find your part? Send us the number and we'll match it.
The best choice for rotary motion in vacuum
Apex Vacuum ferrofluid feedthroughs transfer rotation across the vacuum boundary using a magnetically held liquid seal instead of a dynamic shaft seal. The result is exceptional vacuum integrity, smooth rotation and long service life.
- Hermetic, leak-tight rotary motion transfer
- Excellent performance in HV and UHV systems
- Low outgassing and particle generation
- Long operating life with minimal maintenance
- Smooth, stable torque characteristics
Vacuum range
High vacuum through ultra-high vacuum.
Seal technology
Magnetically retained ferrofluid rings.
Continuous rotation
Smooth rotary motion with no seal drag spikes.
Clean design
Suited to contamination-sensitive processes.
Low leakage
Ideal for sensitive vacuum processes.
Bakeable options
Model-dependent designs for UHV bakeout.
What is a ferrofluid feedthrough?
A ferrofluid feedthrough passes a rotating shaft through the chamber wall while keeping a hermetic seal. Instead of an O-ring rubbing on the shaft, it uses a liquid that is held in place by magnets.
- Magnetic circuit. A permanent magnet and pole pieces surround a magnetically permeable shaft, creating intense magnetic fields in small radial gaps.
- Liquid O-rings. Ferrofluid, a fluid carrying suspended magnetic particles, is pulled into those gaps and forms a series of liquid sealing rings around the shaft.
- Staged pressure hold. Each ring holds part of the pressure difference, so together they seal atmosphere from vacuum.
- Frictionless sealing. The shaft rides on bearings outside the vacuum and turns freely. Nothing solid touches the shaft at the seal, so there is nothing to wear.
Standard specifications
Typical performance for standard Apex Vacuum ferrofluid feedthroughs. See the catalog for model-specific torque, speed and dimensional data.
| Standard rotary seal feedthrough | |
|---|---|
| Leak rate | 1 × 10⁻⁹ std cc/sec, He |
| Vacuum range | 8 × 10⁻⁷ Torr |
| Max. operating pressure | 28 psi |
| Bearing lubrication | Fomblin / Krytox |
| CF flange models | |
|---|---|
| Leak rate | 1 × 10⁻¹¹ std cc/sec, He |
| Vacuum range | 5 × 10⁻¹⁰ Torr |
| Standard ferrofluid | |
|---|---|
| Base oil | Hydrocarbon |
| Max. operating temperature | 0 – 80 °C |
| Best for | Most clean, inert-gas vacuum processes |
| Reactive gas ferrofluid | |
|---|---|
| Base oil | Perfluorinated polyether (PFPE) |
| Best for | Processes using reactive or aggressive gases |
CF (ConFlat®)
Metal-sealed flanges for UHV systems and the lowest leak rates.
KF / NW
Quick-clamp flanges for compact, easily serviced installations.
ISO
Larger flanges for bigger process chambers.
Custom shaft lengths, torque ratings and mounting options are available to match specific application requirements.
Ferrofluid rotary feedthrough models
Solid and hollow shaft designs in every common mounting style. Each model is detailed in the Apex feedthrough catalog.
Custom Ferrofluid Rotary Seals
Need a special shaft length, flange, torque rating or mounting? Send a drawing or your requirements and we'll quote a custom feedthrough.
Find the Apex equivalent to your current feedthrough
Type any Apex, Lesker, Ferrotec or Rigaku part number to find the matching Apex Vacuum model. All standard Apex feedthroughs are 316 stainless steel.
| Apex p/n | Lesker p/n | Ferrotec p/n | Rigaku p/n |
|---|---|---|---|
| Solid Shaft · CF Flange | |||
| SFN025NN-C133 | KLFDCF025133 | FE103915 | FD-CFM-0250 |
| SFN025NN-C275 | KLFDCF025275 | FE103532 | FD-CF-0250 |
| SFN025WN-C275 | KLFDCF025275W | FE103501 | FD-CF-0250-W |
| SFN038NN-C275 | KLFDCF037275 | FE103154 | FD-CF-0375 |
| SFN038WN-C275 | KLFDCF037275W | FE103912 | FD-CF-0375-W |
| SFN050NN-C275 | KLFDCF050275 | FE103909 | FD-CF-0500 |
| Solid Shaft · O-Ring Flange | |||
| SFN050NN-O6 | KLFDOF05060 | FE103244 | FD-F1-0500 |
| SFN050WN-O6 | KLFDOF05060W | FE103182 | FD-F1-0500-W |
| SFN050WN-O7 | KLFDOF05070W | FE103329 | — |
| SFN075WN-O5 | KLFDOF07550W | FE103904 | FD-F1-0750-W |
| SFN075NN-O6 | KLFDOF07560 | FE103246 | — |
| SFN100WN-O6 | KLFDOF10060W | FE103259 | — |
| Solid Shaft · Thread Mount | |||
| STN019NN-516 | KLFDTM018516 | FE103971 | — |
| STN025NN-716 | KLFDTM025716 | FE103978 | FD-BS-0250 |
| STN0505NN-114 | KLFDTM050114 | FE103191 | — |
| STN0505WN-114 | KLFDTM050114W | FE103204 | FD-BS-0500-W |
| STN075NN-114 | KLFDTM075114 | FE103193 | — |
| STN075WN-114 | KLFDTM075114W | FE103206 | FD-BS-0750-W |
| Solid Shaft · Baseplate Mount | |||
| SBN025NN-100 | KLFDBP02510 | FE103237 | FD-LSR-0250-A |
| SBN025NN-10E | KLFDBP02510E | FE103519 | — |
| SBN025NN-150 | KLFDBP02515 | FE103979 | FD-LSR-0250-C |
| SBN025NN-075 | KLFDBP02575 | FE103236 | FD-LSR-0250-D |
| SBN038NN-100 | KLFDBP03710 | FE103664 | — |
| SBN038NN-150 | KLFDBP03715 | FE103991 | FD-CF-.375-B |
| Hollow Shaft · Cartridge Mount | |||
| HCN050NN | KLFDHC050 | FE132405 | — |
| HCN100NN | KLFDHC100 | FE103319 | 10C-8925-B |
| HCN150NN | KLFDHC150 | FE103320 | 10C-8925-C |
| HCN200NN | KLFDHC200 | FE103321 | 10C-8925-D |
| HCN300NN | KLFDHC300 | FE103322 | 10C-8925-E |
| Hollow Shaft · O-Ring Flange | |||
| HFN050NN-O6 | KLFDHOF05060 | FE103358 | — |
| HFN050WN-O6 | KLFDHOF05060W | FE105395 | — |
| HFN100NN-O7 | KLFDHOF10070 | FE103359 | — |
| HFN100WN-O7 | KLFDHOF10070W | FE105396 | — |
| HFN150NN-O7 | KLFDHOF15070 | FE103360 | — |
| HFN150WN-O7 | KLFDHOF15070W | FE103354 | — |
| HFN200NN-O7 | KLFDHOF20070 | FE103361 | — |
| HFN200WN-O7 | KLFDHOF20070W | FE103921 | — |
| HFN300NN-O10 | KLFDHOF30010 | FE133218 | — |
| HFN300WN-O10 | KLFDHOF30010W | FE133760 | — |
| No match found. Email us the part number and we'll find the Apex equivalent. | |||
Standard lead time: 4–6 weeks. A dash means that brand has no listed equivalent.
Download Cross Reference (PDF)Advantages over traditional rotary shaft seals
| Ferrofluid feedthrough | Dynamic O-ring / lip seal | |
|---|---|---|
| Seal wear | None: no solid contact at the seal | O-rings wear and need replacement |
| Leak paths | Significantly reduced | Leak rate rises as seals wear |
| Particle generation | Very low | Wear debris enters the process |
| Vacuum capability | HV through UHV | Generally limited to rough/high vacuum |
| Maintenance cost | Lower | Recurring seal changes and downtime |
| Long-run stability | Stable vacuum over long run times | Performance drifts over time |
Where Apex ferrofluid feedthroughs are used
Semiconductor processing
Wafer rotation and handling in process tools.
Thin-film deposition
Substrate rotation in sputtering systems.
Vacuum coating & evaporation
Planetary fixtures and rotating tooling in coating chambers.
Load locks & transfer
Motion control in load locks and transfer chambers.
Research & laboratory
Manipulators and sample positioning in R&D vacuum systems.
Optics & surface analysis
Optical, materials science and surface analysis instruments.
Get help selecting the right feedthrough
Have these details ready and our technical specialists can configure the right Apex feedthrough for your system, or match the one you're replacing.
Frequently asked questions
Can an Apex feedthrough replace the brand I'm using now?
In most cases, yes. Search the competitor cross reference table on this page to find the equivalent Apex model. If your part number isn't listed, email it to info@schoonoverinc.com and we'll match it.
Standard or reactive gas ferrofluid, which do I need?
Standard ferrofluid uses a hydrocarbon base oil and suits most clean processes from 0 to 80 °C. If your process uses reactive or aggressive gases, choose the reactive gas ferrofluid, which uses a perfluorinated polyether (PFPE) base oil.
What leak rate can I expect?
Standard models are rated at 1×10⁻⁹ std cc/sec helium. CF flange models reach 1×10⁻¹¹ std cc/sec helium and a vacuum range of 5×10⁻¹⁰ Torr.
Why use a hollow shaft feedthrough?
A hollow shaft lets you pass cooling water, gas lines, wiring or a second shaft through the center of the rotating shaft while keeping the vacuum seal.
Are the feedthroughs bakeable?
Bakeable designs are available on a model-dependent basis for UHV applications. Tell us your bakeout temperature and we'll recommend a suitable model.
Can you build a custom feedthrough?
Yes. Custom shaft lengths, torque ratings, flanges and mounting options can be quoted. Submit your requirements or a drawing for a quotation.
Talk to a feedthrough specialist
Send your current part number, application details or a drawing. We'll recommend the right Apex model or quote a custom design.
