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Finding an effective dynamic surface seal has been a major challenge for decades and even centuries. Since the early introduction and development of automobiles, airplanes, and complex machinery, this challenge has become more and more complex.

Thermoplastics, such as polytetrafluoroethylene (PTFE) lip seals, also called rotating shaft seals, are now increasingly being relied upon.

This article will take a closer look at the life of the powerful PTFE rotating lip seal and its evolution over the years.

Every "superhero" has an origin story. The same is true for PTFE lip seals. Early pioneers used ropes, hides or belts with fat on the axles as some of the initial sealing or sealing elements. However, these seals are prone to leaks and require regular maintenance. Many of today's elastomeric seal companies used to operate as tanneries.

In the late 1920s, the first radial lip seals were made of leather and metal fastener shells. In the late 1940s, synthetic rubber began to replace leather. After 40 years, many manufacturers began to re-evaluate the entire sealing system, and often built the sealing surface into the sealing assembly, and added multiple lips on the vertical and horizontal contact points.

Fluorocarbon Corporation is one such manufacturer. In 1982, Fluorocarbon Corporation acquired SealComp, which was then a small family-owned lip seal company based in Michigan. After the purchase, Fluorocarbon relocated SealComp to a plant in South Carolina that produces metal seals for the nuclear and petrochemical markets.

This new lip seal business focuses on high-pressure hydraulic pumps and motors, military alternators, and other commercial products, including aftermarket diesel truck crankshaft seals and thermostats.

In the mid-1990s, The Fluorocarbon Company was renamed Furon and was acquired by Omniseal Solutions™ in 2001. This adds Furon to Omniseal Solutions™'s already strong spring-energetic seal business, which was established in 1955.

In 1995, an elastic band was added to the outer diameter of Omniseal Solutions™ lip seals. This is done to eliminate the metal-to-metal press fit and to ensure a tight seal between the seal and the customer's housing gland. Later additional functions were added for seal removal and positive stop to locate the seal and prevent incorrect installation.

Elastomer rubber lip seals and OmniSeal® PTFE lip seal products have many similarities and differences.

In structure, these two seals are very similar because they both use a metal shell as a structure, press fit into a fixed shell gland, and a wear-resistant lip material that rubs on the rotating shaft. They also use similar spaces when in use.

The elastic lip seal is the most common shaft seal product on the market, and it is molded directly onto a metal housing that provides the necessary rigidity. Most elastic rubber lip seals use a tension spring as a loading mechanism to achieve a tight seal. Usually, the spring is located directly above the contact point of the seal and the shaft interface, and provides the necessary load to clamp off the oil film.

In most cases, OmniSeal® PTFE lip seals do not use tension springs for sealing. Instead, these seals respond to any load applied to the tension of the sealing lip and the bending radius created by the metal shell. Compared with elastomer lip seals, PTFE lip seals use a wider lip-to-shaft contact pattern. Teflon lip seals also utilize lighter unit loads, but occupy a wider area. Their design has moved in this direction to solve the problem of wear rate, and made these changes to reduce the unit load, also known as PV.

The specific application of PTFE lip seals is to seal rotating shafts, especially those high-speed rotating shafts. If the conditions are challenging and beyond their capabilities, they are an excellent alternative to elastic rubber lip seals.

Essentially, PTFE lip seals are designed to bridge the gap between traditional elastomer lip seals and mechanical carbon face seals. Compared with most elastic lip seals, they can operate at higher pressures and speeds, so they are an excellent substitute.

In the harsh environment of extreme temperature, corrosive media, high surface speed, high pressure or lack of lubrication, their performance will not be adversely affected. A good example of the superior functionality of PTFE is industrial air compressors, which are configured to provide more than 40,000 hours of maintenance-free service.

There are some misunderstandings in the manufacture of PTFE lip seals. The elastic rubber lip seals the mold rubber directly to the metal shell. This metal shell provides the necessary rigidity, while the elastomer takes on the working part of the seal.

In contrast, PTFE lip seals cannot be molded directly onto the metal housing. The PTFE material will not turn into a liquid state or allow the material to flow; therefore, the PTFE lip seal is made by machining the seal, then assembled into the metal shell, and then mechanically clamped.

When selecting an accurately matched sealing solution for rotating applications, important factors should be carefully considered, including shaft speed, surface speed, operating temperature, sealed medium, and system pressure. Your decision should also refer to many other operating conditions, but the above conditions are the main concern.

While owning rights, they are also given great responsibilities. Over time, the focus of Omniseal Solutions™ has shifted to applications that require more PTFE lip seals. The seal's ability to deal with challenging industrial, automotive and aerospace applications is one of its main advantages.

Compared with elastic lip seals, they can operate on rotating shafts at higher pressures and speeds, and their advantages do not stop there. Other advantages of PTFE lip seals include:

The two lip seals commonly used by Omniseal Solutions™ are OmniSeal® PTFE metal housing rotary lip seals and DynaLip® polymer seals, both of which are interchangeable. The main difference between the two lies in their structure. The metal shell seal uses a metal plate to form a sealed shell, and then assembles the sealing lip to mechanically clamp the seal.

OmniSeal® rotating lip seals were created in the early 1970s and can withstand harsh environments with a temperature range of -53 °C to 232 °C, harsh chemical environments, and dry and abrasive media. Dynamic rotary sealing applications of PTFE seals include:

DynaLip® seals appeared approximately ten years after OmniSeal® rotating lip seals. When Omniseal Solutions™ began to focus on mixing and mixing highly explosive materials for military applications, their creation became a necessity. Metal shell lip seals are considered absolutely unsuitable for this purpose because they may come into contact with the rotating shaft of the mixed explosive. Therefore, Omniseal Solutions™ design engineers conceived a metal-free lip seal, but still retains its main advantages.

With DynaLip® seals, since the entire seal is processed from the same polymer material, no metal parts are required. In most cases, an elastomer O-ring is used between the outer diameter of the seal and the hole in the mating housing. O-rings provide tight static sealing and anti-rotation. In contrast, OmniSeal® lip seals can be made of three different materials encapsulated in a metal housing.

Today, the original DynaLip® seals have been introduced in many different versions. They are also very suitable for on-site installation because they do not require special installation tools and are also suitable for applications where the seals need to be removed for cleaning. Due to their simple design, these seals are usually more cost-effective.

How do OmniSeal® PTFE lip seals, DynaLip® polymer seals and other lip seals from OmniSeal Solutions™ change our daily lives?

PTFE lip seals provide excellent sealing capabilities and low friction in dry or abrasive media. They are generally suitable for challenging applications that require speed.

A good example of PTFE lip seals replacing elastomer and carbon face seals is the air compressor market. Omniseal Solutions™ began working with most major air compressor companies in the mid-1980s, where they replaced the leak-prone rubber lips and carbon face seals.

The original design was based on traditional high-pressure lip seals. Over time, as the demand increases and better performance is required, the seals need to have zero leakage and extend the life of the seals.

The development of new technology has prolonged the service life of the seals by more than three times, while maintaining tight leakage control at all times. Therefore, Omniseal Solutions™ PTFE lip seals are considered the industry standard and can provide more than 40,000 hours of maintenance-free service.

Teflon lip seals have excellent leakage control capabilities, can operate at speeds of 1,000 to 6,000 RPM, use a wide range of lubricants, and can operate for long periods of time (15,000 hours), thereby reducing warranty claims. Omniseal Solutions™ provides shaft seals with diameters from 0.500 inches to 6.000 inches (13 mm to 150 mm) for the screw compression industry.

Mixers are another area where seal customization is common in this industry. Omniseal Solutions™ customers in this industry need seals to handle shaft deflection and oscillation up to 0.300 inches (7.62 mm), which is a huge dynamic shaft runout. To solve this problem and working speed, Omniseal Solutions™ provides a patented floating lip seal design.

OmniSeal® lip seals are easy to install, meet strict EPA leakage requirements, are also compatible with oil and refrigerant, and can be used in tight spaces throughout the life of the pump.

In addition, Omniseal Solutions™ lip seals can cope with the dynamic sealing environment, extreme speed, and Pressure and temperature, in more applications.

Their seals are also used in equipment requiring FDA-approved materials for the following machinery:

All of these are demanding applications that require very low seal friction resistance to maintain a low temperature. In addition to complying with FDA standards, the seal must also be free of cavities that may cause retention of the sealing material, and must be compatible with acids, alkalis, and detergents. They also need to handle high-pressure washing and pass the IP69K test.

Omniseal Solutions™ lip seals are used in auxiliary power units (APU), turbine engines, starters, alternators and generators, fuel pumps, ram air turbines (RAT), and flap actuators. This is a lip seal One of the largest markets.

The APU is deployed on American Airlines Flight 1549 (Hudson Miracle) and provides power to help the plane land safely. Omniseal Solutions™ lip and spring energy storage seals are installed in the core system of this aircraft, which are considered critical to the flight and must be 100% operational when deployed.

There are many reasons why aerospace manufacturers rely on such lip seals. Custom-designed OmniSeal® lip seals provide a tighter seal and higher performance than elastomer seals. They also require less space than mechanical carbon face seals in turbine shafts and external gearboxes.

They can handle temperatures from -65 °F to 350 °F (-53 °C to 177 °C) and pressures up to 25 PSI (0 to 1.7 BAR), with typical surface speeds of 2,000 to 4,000 ft/min (10 to 20 m/s). Some Omniseal Solutions™ solutions in this area can operate at speeds in excess of 20,000 feet per minute, which is equivalent to 102 meters per second.

Another big market is aircraft engine seals, where lip seals are used for external gearbox seals of major aircraft engine manufacturers. Omniseal Solutions™ lip seals are also used in geared turbofan jet engines. This type of engine uses a gear system that separates the engine fan from the low-pressure compressor and turbine so that each module can run at an optimal speed.

Therefore, they can provide higher efficiency. A typical passenger plane burns about half a gallon of fuel per mile. This more efficient engine is expected to save an average of US$1.7 million in operating costs per passenger plane per year.

In addition to supporting the commercial industry, PTFE lip seals are also used in the military field, especially the Ministry of Defense. This includes use in fighter jets, aircraft carriers and helicopters.

Teflon lip seals are widely used in military aircraft; for example, in lift fans used for vertical lift, helicopter gearbox engine seals and their spring energized seals are also used for rotor heads, flaps and slats The actuator seals, as well as the key equipment used to capture the aircraft’s braking system, land on the deck. It is very important that the equipment used for these applications does not malfunction.

Omniseal Solutions™ lip seals are used in some of the most challenging applications in crankshafts, distributors, fuel pumps and cam seals. These applications are used in the racing industry. Naturally, engines are often pushed to their limits.

Most NASCAR fleets and Indianapolis automotive engines use Omniseal Solutions™ lip seals. In fact, every top qualifier and finisher in Indianapolis in 2019 used at least lip seals on the front and rear crankshafts. Omniseal Solutions™ also has a patented design specifically designed for NASCAR to correct common problems that cause PTFE split seals to fail.

In a recent race held at the Daytona Super Speedway, when the crankshaft seal in the throttle plate engine burned under high speed and rapid pressure, a top NASCAR engine manufacturer turned to Omniseal Solutions™ lip seals Pieces. The result is a win-win for everyone, because Brad Keselowski and #2 Penske Ford won the competition with Omniseal Solutions™ lip seals. To further add to this successful event, four of the top five finishers drove cars that were also equipped with engines from this top manufacturer, which also benefited from these lip seals.

Another use of Omniseal Solutions™ lip seals in racing cars is in top fuel blowers. These engines are under extreme conditions, where every component is bent, shaken, and twisted, causing the parts to come into contact with each other, which is usually not what it should be. Therefore, when used at racing speed, the average life span of the top fuel blower is less than five minutes.

Omniseal Solutions™ lip seals are used on the drive shaft of the blower. They can handle temperatures from -40 °F to 350 °F (-40 °C to 177 °C), pressures from vacuum to unknown high-pressure spikes, and shaft speeds of 4,000 to 14,000 RPM.

In turbochargers, OmniSeal® lip seals operate at high speeds of 4,000 to 36,000 RPM and can handle extreme temperature ranges from -40°F to 350°F (-40°C to 177°C), extending the seal The lubrication of life is limited.

The electronic drive and cooling systems in electric vehicles also use Omniseal Solutions™ lip seals. Shaft seals need to run at much higher speeds than gas engines, and most engines run at speeds in excess of 18,000 RPM.

Although all the above examples are only part of the main areas of PTFE applications, they also rely on demanding applications in life sciences, such as piston cup seals for oxygen concentrators, to improve the breathing and mobility of patients. These special piston cup seals use a unique spinning forming technology to minimize the frictional resistance of the seal, thereby prolonging the use time of the device without the need for recharging. Custom hybrid materials help maximize the performance of this application.

Omniseal Solutions™ lip seals also have an impact in rescue applications. When firefighters spray foam flame retardants, they are used to push the fluid in the pump system. Compared to PTFE seals, most elastic rubber lip seals cannot withstand the chemicals used in these systems.

No matter what your needs are, Omniseal Solutions™ has gained extensive experience in designing high-quality, innovative sealing solutions to solve and improve performance in specific applications. Through a joint engineering approach, Omniseal Solutions™ has worked with customers’ engineers from the beginning of the project to develop and meet specific requirements, from the best sealing jacket material formulation, sealing jacket design configuration to the best spring energizer configuration, At the best result.

Omniseal Solutions™ is always looking for ways to improve the design and manufacturing of its sealing products. The speed, pressure, and temperature limits of their products are determined through rigorous testing, and they are constantly working to exceed the perceived limits of seals.

Today, Omniseal Solutions™ rotating lip seals on the main turbine shaft of turbine engines can easily operate at speeds and temperatures that no one thought possible a few years ago. Omniseal Solutions™ also focuses on designing features that provide multiple advantages, from transporting mandrels to help keep the seal lip in shape, and custom mandrel designs that are used as multi-purpose installation tools.

This information is derived from materials provided by Omniseal Solutions™ and has been reviewed and adapted.

For more information on this source, please visit Omniseal Solutions™. 

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