Why PTFE Works Well for Hydraulic Linear Seals

Write By: sukoptfe Published In: PTFE Polymer Created Date: 2019-01-12 Hits: 2304

PTFE is commonly used for hydraulic liner seals in just about every industry that uses them.  From guide rings to chevron sets, PTFE hydraulic linear seals have a reputation for durability and excellent tribological performance.  

In this blog post, we are going to discuss why PTFE is so popular for hydraulic linear seals.

Linear Hydraulic Seal Applications

Hydraulic liner seals are found in so many different industries it would be time prohibitive to list them all, so let’s just look at some examples.The construction industry uses them extensively, especially in the hydraulic cylinders used for positioning of the bucket on machines such as excavators, backhoes, skid steer loaders, and compact track loaders.  Wind power turbines have several different areas where they are used, including the pitch cylinder, accumulator, lock cylinder, yaw break, and main brake.

They are also used with forestry equipment, such as feller bunchers and skidders, as well in agricultural equipment, where they can readily be found on combines. In the manufacturing industry, they are key to processes such as injection molding and die casting.  They can also be found in aerospace applications as well as oil and gas.

Purpose of Linear Hydraulic Seals

Like most seals, linear hydraulic seals prevent leakage (which also helps prevent soil contamination in agricultural vehicles), retain lubricants in appropriate areas, aid in regulating pressure, and keep contaminations out, including abrasive media that could otherwise seriously damage linear hydraulic components.  They can also act as guides to components moving relative to one other and, if needed, handle radial loads that may occur.  

Desirable Properties in Hydraulic Seals

To begin, linear hydraulic seals need to have:

  • good dimensional stability
  • extremely low friction
  • excellent wear resistance

They also need to have a good combination of hardness and flexibility. Hydraulic sealing materials need to be compatible with mineral and synthetic oils, as well as other types of hydraulic fluids.

PTFE Linear Hydraulic Seals

PTFE works well for many of the applications discussed.  It can handle some of the most intense environments that combine extreme temperatures, high pressures, and aggressive chemicals. Because of its special properties and unbelievable low friction, PTFE also works extremely well in dry-running conditions.  Its wear resistance properties are very good, as is its dimensional stability.  PTFE provides excellent chemical resistance, which means that is compatible with just about all types of lubricants and hydraulic fluids that it might be exposed to.  Its temperature range is from -95°F to 480°F.  Finally, since some grades of PTFE are FDA approved, it works very well when hydraulic linear seals are implemented in the food and drug industry.

Applications for PTFE Hydraulic Seals

When it comes to seals that are used for accurately positioning cylinders, PTFE is a first choice primarily because of its tribological properties, which include minimized stick-slip and outstanding start up performance.  Various grades of PTFE are available which include different additives, such as graphite, carbon, and MoS2. Depending on the grade uses, PTFE can be used in:

  • o-rings
  • anti-extrusion rings
  • chevron sets
  • guide strips
  • piston seal slide rings

Conclusion

If you are designing a system that makes use of hydraulic linear seals, remember that PTFE is widely used and has excellent properties that have made it indispensable in many hydraulic applications.