Synertech Stock
Product codes
Details
C / CS Rotary Shaft Seals
The rotary shaft seals of the C series and the CS variant, commonly known as metal-cased seals with an exposed outer metallic armor (Type B / BS or Type C / CS), are advanced dynamic seals engineered to ensure optimal containment of high-viscosity lubricants, oils, and greases. Unlike the rubber-covered series, they feature a ground or machined outer metal shell that is mechanically pressed for a steel-on-steel interference fit into the housing bore. This structural design ensures robust retention and perfect orthogonal alignment, preventing displacement or skewing even under heavy vibrations or significant structural thermal expansion. The primary sealing lip is energized by a garter spring, creating a constant hydrodynamic barrier on the shaft counterface.
Type C (Standard Metal-Cased)
Single dynamic sealing lip profile equipped with an internal garter spring and an entirely exposed, ground outer metallic shell, ideal for rigid and stable interference fit housings.
Type CS (Dust Lip Variant)
Geometric evolution featuring an additional front protective lip (springless dust lip). Specific for isolating the dynamic sealing zone from coarse external contaminants, dust, and environmental debris.
Materials and operating conditions
| Material / Compound | Peripheral Speed | Temperature | Max Pressure |
|---|---|---|---|
| NBR Nitrile Rubber 70/80 ShA + Steel Case | Up to 12.0 m/s Up to 0.5 m/s in low-speed applications | -30 / +100 °C | 0.05 MPa Standard atmospheric pressure |
| FKM Fluoroelastomer / Viton + Steel Case | Up to 35.0 m/s | -20 / +200 °C | 0.05 MPa Standard atmospheric pressure |
Garter spring
Mineral oils, synthetic lubricants, industrial greases, and water (subject to verification of stainless steel spring).
Main features
Constant radial load
The spring embedded in the back of the lip exerts a calibrated and continuous radial pressure on the rotating shaft diameter. This compensates for elastomer aging, micro-misalignments (run-out), and physiological wear, keeping the dynamic sealing area tightly sealed.
External metal case
The rigid exposed outer metal shell guarantees a stable, permanent and definitive fit within the housing bore. It eliminates any risk of accidental pop-out or blowout caused by pressure peaks or severe thermal differentials.
Sealing edge
The primary sealing lip is finished with a precision sharp geometric trim. The angle creates a hydrodynamic wedge that leverages the surface tension of the oil film to limit leakage and self-lubricate the shaft contact track.
Why choose Types C/CS
Superior Mechanical Anchor
The bare metallic outer finish provides an iron-clad grip within housings made of materials with similar thermal expansion coefficients, ensuring millimetric stability.
Perfect Orthogonal Mounting
The structural rigidity of the metal case facilitates perfectly perpendicular insertion relative to the rotating shaft axis, completely eliminating misalignment errors.
Variable Protection (C vs CS)
The modularity of the design allows selecting version C for minimum frictional resistance, or version CS when the operating environment demands full shielding from external dust.
International Standards: Manufactured in strict compliance with the structural design specifications of DIN 3760 and ISO 6194/1 standards.
Available configurations
Standard Type C/CS (NBR 70)
The classic configuration featuring an exposed metal case coupled with a nitrile rubber compound. It represents the primary choice for retaining standard mineral oils and greases on gearboxes and standard industrial components.
Premium Type C/CS (FKM / VITON)
Elite configuration developed for high peripheral speed shafts (up to 35 m/s) or operating under severe thermal conditions in direct contact with synthetic lubricants and chemically aggressive fluids.
Market Cross-References
| Manufacturer | Basic Metal-Cased Type (Type C / NBR) | Metal-Cased with Dust Lip (Type CS / FKM) |
|---|---|---|
| Net Seals | B/SB/CR Oil Seal Series | Viton BS/SBB/CR FKM Oil Seal Series |
| Freudenberg (Simrit) | Simmerring B Profile | Simmerring BS FKM Profile |
| Parker Prädifa | SB/CR Profile | SBS (FKM) Profile |
| Dichtomatik | WB Profile | WBS FKM Profile |
| Kastas Sealing Tech. | K22 Profile | K28 (FKM) Profile |
| Corteco | Metal-cased Type B Oil Seal Series | Metal-cased Type BS Viton Oil Seal Series |
| SKF | External Metal Armor Seals (CRW1) | Viton Dust Lip Seals (CRWA1) |