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Dynamic Seal Technology From FTL
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Date Added: 4th May 2012
If you have ever seen, for example, an open cast mining site, you will immediately recognise that the dust laden atmosphere would play havoc with mechanical drives and braking components of the very big and expensive yellow machines if they weren't protected.
Something special is needed for this extremely arduous type of duty and this is supplied by FTL's mechanical face seals using dynamic seal technology. These face seals form the primary defence for bearings from ingress of angular rock dust and stones into the immediate vicinity of the bearing.
The mechanical face seals range supplied by FTL utilise the dynamic seal technology of two especially shaped cast iron rings that have been finely lapped to form a radially tapering sliding mating surface. As the mating surfaces rotate they are pressed together axially by compressed elastomer rings retained within a recessed housing on each side.
The essential feature of this type of heavy duty face seal is the continuous lubrication of the mating cast iron surface with oil or grease. To achieve this, the annular space retained by the face seal and the housing is partially filled with SAE80 or SAE90 grade oil.
In some applications, such as conveyor wheel bearings or brakes, grease is specified. The mating surface is continuously lubricated by capillary action as well as centripetal force. If the annular space is filled to about 2/3 full, the mechanical face seal will usually last for the life of the assembly.
Why cast iron rather than stainless steel or PTFE? Well, the specially alloyed Duronit or Coronit cast iron used in the sliding rings have especially high corrosion and hardness for the best durability in the arduous duty they are used in. For higher sliding speeds in the <12 m/s range, Coronit cast iron is specified.
The separate elastomer rings that provide both the sealing between housing and the sliding ring and the energising axial pressure are profiled either as ‘O' rings, or trapezoidal section rings. Materials include Nitrile (NBR), Hydrogenated Nitrile (HNBR), Viton® or FPM.
As you can imagine, the range of applications and manufacturers of the heavy duty machinery, is very wide and therefore, the range of standard mechanical face seals is corresponding large. New and bespoke designs for both OEM and for retrofitting are also possible.
The differences relate to diameter of seal, sliding speed, mating pressure required for dynamics of the seal's action, axial movement and lubrication.
More from this supplier | More from this category: Sealing Products
More from this subcategory: Mechanical Seals