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Finding effective seals for dynamic surfaces has been a major challenge for decades and even centuries, and has become increasingly challenging since the advent and development of automobiles, aircraft, and sophisticated machinery.
Today, thermoplastics such as polytetrafluoroethylene (PTFE) lip seals (also known as rotary shaft seals) are increasingly being used.
In this article, we’ll take a closer look at the life of a high-performance PTFE rotary lip seal and its evolution over time.
Every “superhero” has an origin story. The same applies to PTFE lip seals. Early pioneers used rope, rawhide, or thick belts as some of the first seals or sealing elements on wheel axles. However, these seals are prone to leaking and require regular maintenance. Many of today’s elastomeric seal companies were once tanneries.
In the late 1920s, the first radial lip seals were made from leather and metal boxes with fasteners. In the late 1940s, leather began to be replaced by synthetic rubber. After 40 years, many manufacturers are beginning to rethink their entire sealing system, often integrating the sealing surface into the seal assembly and using multiple lips with vertical and horizontal contact points.
Fluorocarbon is one such manufacturer. In 1982, Fluorocarbon acquired SealComp, then a small family-owned lip seal manufacturing business based in Michigan. Following the acquisition, Fluorocarbon Company relocated SealComp to a plant in South Carolina to produce metal seals for the nuclear and petrochemical industries.
This new lip seal business specializes in high-pressure hydraulic pumps and engines, military alternators and other commercial products including diesel truck crankshaft seals and thermostats.
In the mid-1990s, The Fluorocarbon Company changed its name to Furon and was acquired by BD SEALS Solutions™ in 2001. This adds Furon to BD SEALS Solutions™’s already strong spring seal business, founded in 1955.
In 1995, elastomeric tape was added to the outside diameter of the BD SEALS Solutions™ lip seal. This is done in order to eliminate metal-to-metal pressing and ensure a tight seal between the seal and the customer’s body seal. Additional features were later added for seal removal and active stops to detect the seal and prevent incorrect installation.
There are many similarities, but also many differences, between elastomeric rubber lip seals and BD SEALS PTFE lip seals.
Structurally, both seals are very similar in that they use a metal body pressed into a stationary body seal and a wear-resistant lip material that rubs against a rotating shaft. They also use the same amount of space when in use.
Elastomeric lip seals are the most common shaft seal on the market and are molded directly into a metal housing to provide the required rigidity. Most elastomeric rubber lip seals use an extension spring as the loading mechanism to ensure a tight seal. Typically the spring is located just above the point of contact between the seal and the shaft, providing the necessary force to break off the oil film.
In most cases, PTFE lip seals do not use an extension spring to seal. Instead, these seals respond to any load applied to the stretching of the sealing lip and the bending radius created by the metal body. PTFE lip seals use a wider contact pattern between lip and shaft than elastomeric lip seals. PTFE lip seals also have a lower specific load, but have a wider contact area. Their design was aimed at reducing wear rates and changes were made to reduce unit load, also known as PV.
A special application of PTFE lip seals is the sealing of rotating shafts, especially shafts rotating at high speeds. When conditions are challenging and beyond their capabilities, they are an excellent alternative to elastomeric rubber lip seals.
Essentially, PTFE lip seals are designed to bridge the gap between traditional elastomeric lip seals and mechanical carbon face seals. They can operate at higher pressures and speeds than most elastomeric lip seals, making them an excellent alternative.
Their performance is not adversely affected by harsh environments with extreme temperatures, corrosive media, high surface velocities, high pressures or lack of lubrication. An excellent example of PTFE’s superior capabilities are industrial air compressors, rated to operate over 40,000 hours without maintenance.
There are some misconceptions regarding the production of PTFE lip seals. Elastomeric rubber lip seals press the rubber directly against the metal housing. The metal body provides the necessary rigidity, and the elastomer takes on the working part of the seal.
In contrast, PTFE lip seals cannot be cast directly onto a metal housing. PTFE material does not go into a liquid state or a state that allows the material to flow; Therefore, PTFE lip seals are made by machining the seal, then assembling it into a metal housing, and then mechanically clamping it.
When selecting a precision seal solution for rotating applications, important factors including shaft speed, surface speed, operating temperature, sealing medium, and system pressure must be carefully considered. There are many other operating conditions to consider when making your decision, but the ones listed above are the main ones.
With rights comes great responsibility. Over time, the focus of BD SEALS Solutions™ has shifted to applications requiring more demanding PTFE lip seals. One of the seal’s key benefits is its ability to perform in challenging environments in industrial, automotive and aerospace applications.
They can operate at higher pressures and speeds on rotating shafts than elastomeric lip seals, and the benefits don’t stop there. Other benefits of PTFE lip seals include:
BD SEALS Solutions™ Two common lip seals are BD SEALS PTFE metal body rotating lip seals and DynaLip polymer seals, both of which are interchangeable. The main difference between them is their design. Metal housing seals use sheet metal to form a sealed housing and then install a sealing lip to mechanically clamp the seal.
Invented in the early 1970s, BD SEALS lip seals are designed to perform in harsh environments ranging from -53°C to 232°C, harsh chemical environments, and dry and abrasive environments. Dynamic PTFE rotary seals are used in the following applications:
DynaLip seals predate BD SEALS rotary seals by about ten years. Their creation became necessary when BD SEALS Solutions™ began working on mixing and compounding explosive materials for military applications. Metal-cased lip seals are considered completely unsuitable for this purpose due to the possibility of them coming into contact with the rotating shaft of the mixed explosive. That’s why BD SEALS Solutions™ design engineers developed a lip seal that is metal-free while still maintaining its key benefits.
When using DynaLip seals, the need for metal parts is completely eliminated because the entire seal is made from the same polymer material. In most cases, an elastomeric O-ring is used between the outer diameter of the seal and the mating housing bore. O-rings provide a tight static seal and prevent rotation. In contrast, BD SEALS lip seals can be made from more than three different materials and are enclosed in a metal housing.
Today, the original DynaLip seal has spawned many different versions that are also ideal for field installation as they require no special tools for installation and are also suitable for applications that require the seal to be removed for cleaning. Due to their simple design, these seals are often more economical.
How do BD SEAL PTFE lip seals, DynaLip polymer seals and other lip seals from bd seals Solutions™ change our daily lives?
PTFE lip seals provide superior sealing properties and low friction in dry or abrasive environments. They are often used in complex applications where speed is required.
The air compressor market is a good example of how PTFE lip seals are replacing elastomeric and carbon mechanical seals. BD SEALS Solutions™ began working with most major air compressor companies in the mid-1980s, replacing leak-prone rubber lip seals and carbon face seals.
The original design was based on a traditional high-pressure lip seal, but over time, as demand increased and higher performance was required, the seal was designed to have zero leakage and extended service life.
The new technology has been developed to more than double seal life while maintaining tight leak control at all times. As a result, Omniseal Solutions™ PTFE lip seals are considered the industry standard, providing over 40,000 hours of maintenance-free service.
PTFE lip seals provide superior leakage control and are capable of operating from 1000 to 6000 rpm with a variety of lubricants and for extended periods of time (15,000 hours), reducing warranty claims. bd seals Solutions™ offers shaft seals for the screw compression industry with diameters ranging from 0.500 to 6000 inches (13 to 150 mm).
Mixers are another industry area where seal customization is widespread. BD SEALS Solutions™ customers in this industry require seals that can handle shaft deflection and runout up to 0.300 in. (7.62 mm), which is a significant amount of dynamic shaft runout. To solve this problem and improve operating speed, BD SEALS Solutions™ offers a patented floating lip seal design.
bd seals lip seals are easy to install, meet stringent EPA leakage requirements, and are oil and coolant compatible for use in confined spaces throughout the life of the pump.
In addition, Solutions™ lip seals are designed for dynamic sealing conditions, extreme speeds, pressure and temperature problems, and many other applications.
Their seals are also used in equipment that requires FDA approved materials for use in machines such as:
All of these applications require very low seal friction resistance to reduce temperature. In addition to meeting FDA standards, seals must be free of cavities that could cause jamming of the material being sealed, and must be compatible with acids, alkalis and cleaning agents. They must also withstand high pressure washing and pass IP69K testing.
bd seals Solutions™ lip seals are used in auxiliary power units (APU), gas turbine engines, starters, alternators and generators, fuel pumps, pressure turbines (RAT) and flap actuators, one of the largest markets.
The APU was activated on US Airways Flight 1549 (“Miracle on the Hudson”) to provide power to the aircraft for a safe landing. BD SEALS Solutions™ lip and spring seals are installed in this aircraft’s core system, which is considered flight critical and must be 100% operational upon deployment.
There are many reasons why aerospace manufacturers rely on these lip seals. Specially designed BD SEALS lip seals provide a tighter seal and improved performance than comparable elastomeric seals. They also require less space than mechanical carbon mechanical seals on turbine shafts and external gearboxes.
They can withstand 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 2000 to 4000 feet per minute (10 to 20 m/s). Some bd seals 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 major market is aircraft engine seals, where lip seals are used in external transmission seals by large aircraft engine manufacturers. bd seals Solutions™ lip seals are also used in geared turbofan jet engines. This type of engine is equipped with a gear system that separates the engine fan from the low pressure compressor and turbine, allowing each module to operate at optimal speed.
Thus, they can provide increased efficiency. A typical airliner burns about half a gallon of fuel per mile, and more efficient engines are expected to save an average of $1.7 million in operating costs per airliner per year.
In addition to supporting commercial industries, PTFE lip seals are also used in the military, especially by the Department of Defense. This includes use on fighter aircraft, aircraft carriers and helicopters.
PTFE lip seals are widely used on military aircraft; For example, in vertical lift fans, helicopter gearbox motor seals and their spring-loaded seals are also used for rotor head seal parts, flaps and slats, and key equipment in the braking system used to catch an aircraft. Landed on the deck. It is important to ensure that the equipment used for these purposes does not malfunction.
BD SEALS Solutions™ lip seals are suitable for some of the most challenging applications such as crankshafts, distributors, fuel pumps and cam seals found in the racing industry, where naturally engines are often pushed to their limits.
Most NASCAR teams and Indianapolis Motorsports engines use BD SEALS Solutions™ lip seals. Almost every qualifier and finisher at Indianapolis in 2019 used lip seals on at least their front and rear crankshafts. bd seals Solutions™ also features a patented design created specifically for NASCAR to eliminate common problems that cause PTFE split seal failure.
When the engine’s throttle crankshaft oil seal burned out at high speeds and high pressure during a recent race at Daytona Superspeedway, a leading NASCAR engine manufacturer turned to bd seals Solutions™ lip seals. The result was a win for everyone: Brad Keselowski and the No. 2 Penske Ford won the race using bd seals Solutions™ lip seals. To further enhance this successful event, four of the top five finishers drove cars equipped with leading manufacturer engines that also benefited from these lip seals.
Another racing application for BD SEALS Solutions™ lip seals is in overhead fuel injectors. These engines are subjected to extreme conditions where every component bends, shakes and twists, causing contact between parts that should not normally occur. Therefore, the average lifespan of an overhead fuel injector is less than five minutes when used at racing speeds.
Post time: Oct-10-2023