PTFE Spiral Backing
Back-up Rings have no intended sealing function.
 
They are protective and supporting elements made from extrusion-resistant materials which generally have a rectangular cross section. They are installed in a groove together with an elastomeric sealing element preferably with a corresponding O-Ring in static applications.Due to the tight fit of the Back-up Ring in the housing, they prevent extrusion of the pressurised elastomeric sealing element into the sealing gap.
rotatex
rotatey
rotatez

Advantages

  • Use of O-Rings in high pressure applications
  • Use of O-Ring materials with a low hardness
  • Compensation of radial sealing gaps
  • Use for internal and external sealing applications - Reciprocating and rotating movements possible
  • Compensation for large temperature fluctuations
  • Static and dynamic applications

Materials

Back-up Rings are as standard manufactured from virgin PTFE. In view of the unfavourable cold flow behaviour of virgin PTFE, these Back-up Rings are used only for low to medium loads. For higher load requirements, filled PTFE materials (with glassfibre, bronze, carbon, etc.) have to be used. For sealing against high pressures, Back-up Rings made from specially modified thermoplastic materials are used.For the series production of larger quantities, injection moulded Back-up Rings can be manufactured, e.g. NBR 90 Shore A, FKM90 Shore A, or thermoplastic elastomers (TPE) on request.

· Static applications: Up to approx. 250 MPa depending on the Back-up Ring
· Dynamic applications: Reciprocating up to approx. 40 MPa
· Oscillating/slowly rotating up to approx. 15 MPa
· Speed: Reciprocating or rotating up to approx. 2 m/s depending on the material Operating temperature: - 200 °C to + 260 °C depending on the material

Applications