Rod Wiper or Wiper Seal
Wiper seals are generally used for linear and reciprocating dynamic sealing applications. They are also called as scrappers, dirt wipers, wipers, rod wipers etc.
Wiper seals prevent contamination of hydraulic and pneumatic ram systems by restricting the entry of external particles, fluids or other foreign substances from entering the hydraulic and pneumatic system.
Contaminants can result into major significant damage to the rod shaft, cylinder bore walls, hydraulic valves, seals and other components. One of the primary causes of premature seal and component failure in a fluid power system is contamination. It should be noted that rod seal failure is normally a swift result of wiper failure. Special attention must be given while choosing the wiper seal design with few considerations :
- Groove Geometry
Snap In Design
Generally the least expensive wiper, it is more costly however, this style provides the best long term wiping performance
Press In Design
The wiper designed for press-installation is typically to machine the groove; more costly while the machining of the gland is less costly
- Lip Geometry:
When the rod extends past the rod seal, a thin film of oil remains on the rod trapped in microscopic surface imperfections. The thickness of the oil film depends upon the surface finish, rod seal and surface speed of the rod. During the return stroke, this thin film can be removed by an aggressive wiper lip, resulting in system leakage. It is important to properly pair the wiper and rod seal. If the wiper and the rod seal are not matched, leakage and premature failure can occur. An aggressive wiper lip requires an aggressive rod seal lip design or a redundant High-Performance Sealing System.
Further considerations are the lip geometry. We distinguish between:
1. Single lip, straight wiper lip design is the most aggressive. It offers the best scraping and dirt removal performance and is recommended for most sealing applications with high contamination.
2.Single lip, beveled wiper lip or chamfered wiper lip is less aggressive. The beveled lip allows the microscopically thin oil film on the rod to be retracted back into the system while providing adequate dirt exclusion in less contaminated environments.
3.Single lip, rounded seal lip is the least aggressive sealing lip and is typically used in pneumatic applications to maintain a microscopically thin oil or grease film on the rod to keep the piston bearing and seal lubricated .
4.Double or redundant wiper lips are one of the most effective ways to improve a system’s sealing performance. This wiper design must be paired with one of our Long-Life Rod Seals to provide for the driest long-life rod sealing available. It eliminates the release of built-up fluid pressure (pressure trap) between the wiper and the rod seal, also known as “burping,” by releasing built-up fluid pressure back past the rod seal into the system.
Wiper seal or Rod wiper with sealing lips
3. Environment:
In applications where the equipment is exposed to heavy dirt, mud and moisture, all-weather conditions or where the rod of the cylinder is vertical or upward orientated, it is possible for moisture or other contaminants to get past the wiper, leading to corrosion and damage of components and seals. For these applications, We offer special design wiper seals. For more information, please do write to us.