PTFE Rotary Lip Seal Design
When choosing a metal-cased rotary lip seal, you have many options. One design choice to be made is
what material to use for the lip. Most rotary shaft seals have a lip that is made of a thermoplastic (such as PTFE, PP, or PVC), an elastomer (natural or synthetic rubber), a thermoplastic elastomer (for example, PE), or a metal. In this post, we are going to look at what makes PTFE a competitive choice for a metal-cased rotary lip seal by investigating six things your competitors dont want you to know.
Here are some additional blog posts here at Advanced EMC Technologies on polymer seals:
- Which is Superior for a PTFE Rotary Shaft Seal: A Metal Case or a Non-Metal Case?
- 6 Things You Should Know about Cryogenic Seals
- 5 Top Reasons Why PEEK is Popular Choice for Seals
6 Key Features of PTFE Rotary Lip Seals
Feature #1 PTFE rotary lip seals are used in a myriad of environments
Metal-cased PTFE rotary seals are found in so many industries and applications: turbine engines, mixers, robotics, compressors, molding machines, pharmaceutical and food processing, steel mills, blowers, fuel pumps, vacuum pumps, blowers, drilling and tapping spindles, power steering, electric motors shafts, and medical drills.
Feature #2 PTFE is perfect for use in the food, dairy, and pharmaceutical industry
First, PTFE is available in forms that are FDA, USDA, and USDA-3A compliant. Second, PTFE seals can be easily removed for cleaning, which is a necessity in these industries. Third, its wide temperature range and resistance to chemical attack mean that it will survive even the harshest sanitation regimens that may be required.
Feature #3 Metal-cased PTFE rotary lip seals are meant for tough environments
PTFE rotary lip seals are ideal for the toughest of environments: fast surface speeds up to 7,000 ft/min, high temperatures (up to 450° F), aggressive chemicals, abrasive media, little to no lubrication, cryogenic temperatures, and pressure up to 500 psi.
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Feature #4 PTFE rotary lip seals offer more than elastomer seals
When compared to elastomers, PTFE offers much lower friction, outstanding chemical resistance, a wider range of operating temperatures, lower lip wear, reduced break out friction, insensitivity to ultraviolet and oxidation, and an unlimited shelf life. Characteristics of PTFE can also be further improved through the addition of various fillers.
Feature #5 Metal-cased PTFE rotary lip seals are great options for challenging designs
Sometimes a combination of design requirements seem to eliminate all your sealing options, but PTFE can rise to the challenge. If you are working with shaft design that requires a unhardened shaft, PTFE is soft enough to not damage the surface. If you face the situation where there may be dry runs or extremely limited lubrication, PTFE can still outperform its competitors. If the equipment may experience extended downtimes, PTFE has very low breakaway forces.
Feature #6 PTFE seals can be used with a variety of media
PTFE lip seals have successfully been used to seal in (or out, as the case may be) all types of media, including granules, synthetic lubricants, powders, steam, resins, heat transfer oils, chemical waste water, foodstuffs, glue, and more.
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Conclusion
Metal-cased PTFE rotary lip seals are in just about every sealing applications imaginable, are available in approved form for use in FDA regulated industries, survive in some of the harshest seal environments, offer better characteristics than elastomers, are great for meeting challenging design requirements, and can be used with all kinds of media. So, in conclusion, keep in mind these six crucial facts about metal-cased PTFE rotary lip seals when choosing a seal for you next design.
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