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Mechanical face seals

Application Material Profile Standard Hardness
Shore A
Pressure - (max) bar Temperature Sliding Speed
(max m/sec)
Dimension Price Pressure
Mechanical face seals NBR

Mechanical Face Seals - also known as Heavy Duty Seals, Lifetime Seals, Floating Seals, Duo Cone Seals or Toric Seals - are specially designed for rotary applications, often in connection with shafts, in extremely arduous and dirty environments, where they should withstand severe wear and prevent ingress of dust, dirt and water, as well as other harsh and abrasive materials, and where long maintenance-free lifetime is required.

Mechanical Face Seals are normally supplied in sets, with two identical parts, each consisting of a metal ring and an elastomer. The two parts are fixed in the two separate machine parts. One metal ring is mounted in the rotating machine part, while the other is fixed in the stationary part. Thus, the two elastomers press the sliding surfaces of the metal rings against each other, thereby acting as a seal.

The most commonly type of Face Seal uses an O-ring as an elastomer (type 1), while another commonly type uses an elastomer with a diamond-shaped cross section (type 2). The Face Seal with the O-ring elastomer is used in conical cavities while the Face Seal with the diamond-shaped elastomer is used in cylindrical cavities, however, they both have 3 important functions:

  • Through their elasticity, they generate a uniform axial surface pressure, between the two gliding sealing surfaces
  • They act as a secondary static seal, on both the outer and inner diameters
  • They ensure that the metal rings do not rotate with each other, due to the transferred torque

An essential feature of the Mechanical Face Seal is the robust and simple construction, which guarantees very long lifecycles. The selection of the most suitable materials for both the sliding rings and the elastomeric components ensures a very high wear resistance, a fully adequate corrosion protection as well as optimal temperature - and lubricant resistance.


Type 1   Type 2  



Mechanical face seals distinguish themselves in demanding and dirty environments, where they are exposed to extreme and constant strain, due to three outstanding advantages:

  • Protect the sealing space from abrasive dirt and contamination
  • Avoidance of oil or grease leakage from the sealing space
  • Extremely high wear resistance and long lifecycles


Because of the high requirements to the wear resistance, the metal rings are made of cast iron (15Cr3Mo) or bearing steel (GCr15/100Cr6), with a hardness range from 58 to 68 HRC. The extremely good wear resistance of cast iron is reached due to the material properties, the microstructure and its hardness. Cast iron are therefore suitable for extreme working conditions, and can operate at pressures up to 3 bar and gliding speeds up to 2 m/s. For gliding speeds less than 2 m/s and pressure values lower than 1,5 bar, the choice of bearing steel can be a good alternative.

High thermal resistance and a low compression set are two essential material properties for the elastomeric parts. The standard NBR-compound normally meets with the thermal, physical and chemical requirements. However, if higher thermal, physical or chemical resistance is required, the elastomeric parts are also available in HNBR, VMQ or FPM.

Furthermore, the elastomeric materials are offered in various degrees of hardness, so the elastomeric parts can adequately perform its function of generating a permanent and consistent contact pressure between the gliding faces, under different working conditions.

Depending on the media that must be sealed off, it is often possible to offer individual designed material recipes for a special high alloy cast, to substantially increase life span, corrosion and wear resistance of the Mechanical Face Seal. Individual recipes of high alloy cast for sealing solutions, for example in biogas fermentation plants - or machinery with chemical exposure to slurry, shows substantial improvements.


Mechanical Face Seals are designed for solutions used under severe and dirty conditions, extreme weather and corrosive surroundings. The Mechanical Face Seal applications proves exceedingly reliable and functional in a wide range of heavy industries and applications:

  • Machinery for the construction - and building industry
  • Agricultural- and forestry applications
  • Tracked vehicles such as excavators, cranes, military tanks and bulldozers
  • Heavy trucks, wheel loaders, ditch rollers & dump trucks
  • Conveyor systems, concrete mixers & concrete pumps
  • Agriculture machines, tractors & harvesting machines
  • Soil cultivation machineries, harrows, ploughs, fertilizers & hay balers

Due to their outstanding technical features Mechanical Face Seals have achieved worldwide distribution.