O-rings are essential sealing components used in various applications to prevent leakage between two surfaces, however, they do have their limitations. Depending on the material, an O-ring could have higher than preferred friction, low chemical resistance, or confusing coloration. In situations like this, a specialty coating like Parylene or PTFE might be the right answer. In this blog, we will focus on PTFE-coated O-rings, their advantages, and their applications.
What are PTFE-Coated O-rings?
PTFE-coated O-rings are O-rings that are coated with a layer of PTFE material. PTFE, or polytetrafluoroethylene, is a type of fluoropolymer that is known for its non-stick properties, chemical resistance, and high-temperature resistance. When applied as a coating to O-rings, PTFE can provide an additional layer of protection, improving certain properties of the O-ring.
Most of our coating systems are applied using conventional compressed air driven spraying techniques. The coatings are supplied as liquids and are decanted into either gravity fed or pressure fed spraying equipment.
Powder systems such as PFA and FEP are applied electrostatically, where the coating material (powder) and the part receive opposing electrical charges so that the powder will be attracted to the part. This is particularly useful where complex shapes are involved. If you would like to learn more, see our PTFE Coatings page.
Advantages of PTFE-Coated O-rings
PTFE-coated O-rings offer several advantages over other types of O-rings. These include:
- Color Identification: PTFE coatings can be produced in any color. This makes PTFE coated O-rings easy to identify.
- Chemical Resistance: PTFE is highly resistant to chemicals, making the PTFE coating fully functional in applications involving harsh chemicals. However, PTFE coatings are porous, and wear off easily. They will not protect the O-ring from chemical contact.
- High Temperature Resistance: PTFE can withstand high temperatures, making PTFE coatings suitable for applications where high temperatures are expected.
- Low Friction: PTFE has a low coefficient of friction, making PTFE coatings an ideal, clean, dry lubrication for installation purposes.
- Non-stick Properties: PTFE is known for its non-stick properties, which make PTFE-coated O-rings easy to remove and clean.
- Thin Coat: PTFE coatings are extremely thin and typically have virtually no effect on the tolerances of the end part.
Limitations of PTFE-Coated O-rings
While PTFE coatings have their uses, their limitations can sometimes exclude their use from certain applications.
- Poor Dynamic Wear Resistance: PTFE coatings can easily be rubbed off, meaning that they really only function as a one-time-use surface lubricant.
- Flaking: Because PTFE coatings can easily flake off due to dynamic wear, pieces of the coating can sometimes contaminate clean systems.
- Porous: PTFE coatings do not provide additional chemical resistance for the O-ring. Because of this, it is important to use an O-ring material that is resistant to the chemicals and temperatures used in the application.
Applications of PTFE-Coated O-rings
PTFE-coated O-rings are used in various industries, including:
- Chemical Processing: PTFE-coated O-rings are used in chemical processing equipment, where they provide improved installation lubrication, reliable sealing properties, and chemical resistance.
- Aerospace: PTFE-coated O-rings are used in aerospace applications, where they provide high-temperature resistance and easy colored identification.
Conclusion
PTFE-coated O-rings offer useful niche benefits and can be ideal for use in various industries depending on the use case. PTFE-coated O-rings provide an inexpensive dry surface lubricant and color identification system; however, the limitations of PTFE coatings can sometimes make them prohibitive for certain applications. If you are interested in the benefits of other coating types, see our blog about Parylene Coatings. Parylene coatings frequently fill the roles that PTFE coatings fail to. For more information, please visit our website: https://www.canyoncomponents.com/
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