WIPER_SEAL
A wiper seal is an axial seal that creates a seal while allowing a reciprocating shaft to pass through the seals inner bore. The role of the wiper seal is to prevent the ingress of dust and dirt or other foreign bodies, therefore extending the working life of the seal it is protecting.All other functions, such as providing a secondary seal for the rod, are subordinate to this prime.Wiper seals are typically used on hydraulic and pneumatic cylinders, as well as telescopic suspension forks for motorcycles and bicycles.Temperature range of wiper seals is usually between -40° C and +120 ° C and max speed is at 4m/s.
Dynamic function:
To be an effective wiper seal, the wiper lips contact force against the rod must be satisfactory high. This is best achieved with an elastomeric material that has a relatively high hardness. Polyurethane with a hardness of 94° Shore A is a specifically appropriate material for wiper seals. Its properties are also characterized by high modulus (stiffness), very good wear resistance and low compression set. This material type can be used in most types of applications in the temperature range of -40 to +100° C.
Static function:
It is very difficult to reach effective static sealing in the housing for non-reinforced single-acting wipers, designed to be used in closed housing grooves. This is due to the fact that wipers of this group are loosely assembled in the housings. Only the counter force of the sealing lips contact with the rod provides the sealing force between the wiper and the cylindrical surface.At decreasing temperature, when the entire wiper seal is shrinking, the risk for leakage between its outside diameter and the housing occurs. In order to reach acceptable function, this circumstance must be compensated for in the design of the wiper seal. Non-reinforced double-acting wiper seals of nitrile rubber or polyurethane are designed to provide satisfactory static sealing between the wiper seal and the housing. Effective static sealing in the housing can best be reached with metal reinforced wiper seals, designed for press fit assembly.
Advantages:
- Space-saving construction
- Low cost, economical solution
- Simple, easy-construction groove
- Easy installation and removal without tools