by Jackie Johnson Jackie Johnson No hay comentarios

Polymer Bushings: Machine or Injection Mold?

Polymer bushings are found in everything from the food processing industry, where they meet the challenging demands of sanitation and sterilization, to the rugged environments and high shock loads encountered by rear hub bushings on bicycles

Quick Review: Why Polymer Bushings?

Bushings, which are also referred to as plain bearings, are used to reduce the level of friction between two surfaces that are in rotating or sliding contact with one another. They can also serve secondary functions, such as providing additional support and alignment. Polymer bushings are replacing more and more metal bushings because polymers are typically lighter-weight, are more corrosion resistant, lower friction, often dry-running, and can be enhanced with fillers to improve properties such as wear-resistance and strength.

Manufacturing Polymer Bushings

When it comes to manufacturing polymer bushings, there are two primary methods to choose from: machining and injection molding. Both of these methods can generate reliable bearings to extremely tight tolerances, but they have significant differences and situations where one is preferred over the other.

Machining Polymer Bushings

When someone refers to machining, most people think of working with metals such as steel and aluminum, but plastics can also be machined.  Machining is a material removal process where the material that is not needed in the final part geometry is removed with a cutting tool and may involve numerous steps.

Depending on the part geometry, this may involve a lathe (for parts with rotational symmetry). Most modern machining facilities use CNC (Computer Numerical Control) and CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) to make parts that meet strict tolerances and are consistent in their dimensions. For polymer bushings, CNC lathes are typically used and multiple process steps are required to achieve the final part geometry and surface finish, including boring, reaming, and facing.

Benefits to machining include a short lead time and cost-effectiveness for low volume production runs of less than 1,000. Machining also avoids residual stresses (which we will discuss in a moment) that can warp the bushing and works extremely well when there are very tight tolerances or thin walls. Machining is also well adapted for situations where there is a need for non-standard shapes or bushing dimensions.

Spring Energized PTFE Seal

Injection Molding Polymer Bushings

Injection molding is a commonly used polymer manufacturing process that forces molten plastic into steel molds at extremely high pressures. Injection molding machines use a screw system to transport the plastic at high pressure into detailed molds that are typically designed to make multiple parts at a single time. The major expense in injection molding lies in the engineering and fabrication of the molds.

Injection molding of bushings is fast once the tooling is engineered and machined, ideal for production runs over 5,000 parts, and works exceptionally well for bushings that are standard-sized. However, injection molding does have its drawbacks. The most problematic drawback in the context of polymer bushings is residual stresses that develop as the part cools, but it is possible to eliminate these stresses through plastic annealing

There can also be issues with shrinkage and dimensional change, which can make it a poor option if the plastic bushings need to meet high tolerances. In addition, injection molding is not a reliable approach if the bushings have thin walls.

Conclusion

The demand for polymer bushings and plain bearings continues to rise. When it comes time to specify the bushings for an application, it is important to choose the best manufacturing method. For situations with small production runs, non-standard dimensions, tight tolerances, or thin walls, polymer bushings should be machined. When a large production run is involved and the bushings have standard dimensions and/or geometries, injection molding is the best option. 

by Jackie Johnson Jackie Johnson No hay comentarios

The History of ePTFE

Expanded PTFE (or ePTFE), like regular PTFE, is an incredibly versatile and rugged material. And like PTFE, ePTFE began as an accident.

Before we can get to that, however, we should start at the beginning:

When his ideas for expanding the use of PTFE was turned down by his employers at DuPont, chemist Wilbert “Bill” Gore left the company to start his own. And in 1958 Gore and his wife Genevive “Vive” Gore founded W.L. Gore and Associates out of the basement of their Delaware home. During this time, Gore’s company began to serve the burgeoning computer industry by using PTFE to insulate multiple copper conductors and fashion them into ribbon cable resulting in a product known as MULTI-TET.

Bob Gore

Bob Gore recreating his discovery of ePTFE

As the years went on it became clear to Gore that trends in computer technologies meant that computers were becoming smaller and smaller, resulting in the need for less cables for circuitry. In 1968, Gore tasked his son, Robert “Bob” Gore, to come up with a solution. One night in October 1969, Bob Gore was researching a new process for stretching extruded PTFE into pipe-thread tape when he discovered that the polymer could be “expanded.” After several failed experiments in which Bob tried to slowly expand the material even further, he became frustrated and yanked the material. As it turned out, this was the exact conditions PTFE needed to become expanded. This sudden yank resulted in the transformation of solid PTFE into a microporous structure that was about 70% air. This material would later become known as ePTFE, or Gore-Tex.

Today, ePTFE is used in a wide variety of applications. These applications include:

  • Aerospace
  • Automotive
  • Energy
  • Filtration
  • Medical
  • And much more

Interested in learning more about ePTFE and how Advanced EMC Technologies can over you premiere sealing solutions? Contact us today!

by Jackie Johnson Jackie Johnson No hay comentarios

The Illustrious History of PTFE

Spring Energized PTFE Seals

Today PTFE is one of the most widely used materials in the world. So, it may come as a surprise to learn that it was discovered entirely by accident!

In April of 1938, Dr. Roy Plunkett and his assistant Jack Rebok were working as chemists at DuPont’s Chemors Jackson Labritory in New Jersey. On the night of the 6th, they stored the gas they were experimenting on (tetrafluoroethylene) in small cylinders where they were then frozen and compressed.

When the men returned the next day, they discovered that the gas they stored was gone. When they released the nozzle of the cylinders, no gas was released. Thinking this odd, they split the cylinders open to find the gas had turned into a solid, white and waxy material.

This material would later become known as PTFE (polytetrafluoroethylene) or better known by it’s brand name Teflon.

Dr. Plunkett continued research on this strange new material, and found that it was not only one of the slipperiest materials known, but that it also had several other incredible properties such as:

  • Non-Corrosive
  • Chemically Stable
  • Extremely High Melting Point

In 1941, Kinetic Chemicals Inc, a company founded by DuPont and General Motors, patented the new fluorinated plastic. In 1945 the name Teflon was trademarked. By 1948, Kinetic Chemicals was making over two-million pounds of the Teflon brand PTFE.

It wasn’t until 1954, when French-woman Collette Grégoire, wife of engineer Marc Grégoire, asked him to try the material he had been using on fishing tackle on her cooking pans. He subsequently created the first non-stick pans under the brand name Tefal (which is an amalgamation of “Tef” from “Teflon” and “al” from aluminum). The first PTFE-coated pan was introduced in the US in 1961 as “the Happy Pan”. Since then, non-stick cookware has been a staple in kitchens around the world.

Aside from cookware, PTFE has been used in a wide variety of applications, from food processing to the space industry. In fact, PTFE was used in the initial moon landing in 1969, as it was the only plastic that could withstand the extreme atmosphere of space.

Since then, PTFE has become a staple in our everyday lives and will continue to be so for many more years to come.

Need PTFE sealing solutions? Contact us today for more information!

by Sara McCaslin, PhD Sara McCaslin, PhD No hay comentarios

Spring Energized Seals in the Oil and Gas Industry

The oil and gas industry is home to some of the most intense operating conditions for seals: HPHT (High Pressure, High Temperature), corrosive chemicals, and very dangerous repercussions if seals fail. When all other sealing solutions fail, spring-energized seals are often the answer.

Seals in Oil and Gas Applications

Seals are used throughout the oil and gas industry, including applications as diverse as …

  • Anti-Blow Out Seals
  • Couplings
  • Downhole Tools
  • Emergency Release Systems
  • Loading Swivels
  • Logging Tools
  • Quick Connect/Disconnect Couplings
  • Rotary Drill Bits
  • Surface and Subsea Well Heads
  • Swivel Stack Seals
  • Top Drive Units
  • Valves
  • Well Head Connectors

A seal failure in any of these areas could quickly lead to injured personnel, environmental damage, and ruined equipment. Seals for such applications must be rugged, reliable, and chemically resistant. They must be compatible with corrosive chemicals such as H2S, aromatic hydrocarbons, supercritical CO2, oil, and methanol,–and they need to be resistant to chemical permeation, as well. They generally need to be flameproof, tough, and wear-resistant as well.

Spring-Energized Seals

A spring-energized seal has a spring (the energizer) that applies additional force to the seal lip to maintain contact between the lip and the sealing surface. This energizing effect can account for issues related to dimensional changes, extreme pressure variations, wear on the edge of the seal lip, and other phenomena that can lead to a leaking seal. 

With the right choice of spring geometry, a constant force can be applied to the sealing lip to ensure its full engagement with the sealing surface, even through extreme pressure variation, temperature changes, wear on the shaft, and alignment issues. Spring energized seals can also be used with backup rings, or BURs, to prevent extrusion problems with the seal lip.

Lip Materials for Spring-Energized Seals

The seal lip material is also key, with the most commonly used polymers for oil and gas sealing challenges being PEEK and PTFE. They are both chemically inert, tough, wear-resistant, flame resistant, and offer outstanding performance even in the presence of extreme temperatures. Both of these materials work extremely well with spring energizer to result in excellent spring-energized seals for the oil and gas industry. They also have very low coefficients of friction and low CTEs (coefficient of thermal expansion).

PEEK performs well at pressures up to 20 kpsi, has a maximum temperature operating temperature of 500°F, and is also available will fillers to provide additional strength and hardness. Many grades PTFE has a maximum operating temperature close to 575°F and can handle high pressures. They are both dry running, as well, which makes them ideal for situations where traditional lubrication is not feasible.

Conclusion

If you are in the market for a reliable sealing solution for an oil and gas application, be sure to consider spring energized seals. They perform where many other types of seals fail, can be used with backup rings, are commonly used in petrochemical applications, and can be designed with a PEEK or PTFE seal lip for maximum performance.

by Jackie Johnson Jackie Johnson No hay comentarios

The Benefits of Modified PTFE

Spring Energized PTFE Seal

Polytetrafluoroethylene (PTFE) is a chemically resilient fluoroplastic. An incredibly versatile material, PTFE is used (at least in some capacity) in nearly every industry imaginable. PTFE has its limitations, however.

Modified PTFE (or MPTFE) pushes the limits of regular PTFE, offering exciting new possibilities for a wide variety of applications. The reason behind such improvements? MPTFE, also known as TFM (trade name of Daikin) is a copolymer of tetrafluoroethylene and a small quantity of a perfluorinated modifier (perfluoropropyl vinyl ether, PPVE).

In other words, MTFM has added chemicals that make it stronger and more versatile than regular PTFE. And because of its strength and versatility, modified PTFE is used in a wide variety of industries. These include, but are not limited to, automotive, aerospace, medical device, LNG and more.

A Strong and Versatile Material

Modified PTFE has several advantages over regular PTFE. It has a substantially reduced deformation under load- 4% for Modified PTFE vs 10% for PTFE. This, as well as improved flexibility, makes modified PTFE great for devices that need a little give but won’t break under pressure.

MPTFE also has a lower porosity and permeability which helps reduce the amount of liquid absorption, making it perfect for products such as seals for wet environments. On top of that, modified PTFE has smoother surfaces, nonstick and dielectric properties, and a reduced cold flow. It has good metering properties, good electrical and mechanical properties. And with excellent fuel and additive resistance, MPTFE can replace conventional materials such as PTFE and make it easier to use more aggressive lubricants and seal designs.

In Conclusion

As you can see, MPTFE is an incredibly versatile and strong material to use. It can withstand more abuse than the average PTFE, giving it a clear advantage for a variety of applications. Use modified PTFE for your next project and let Advanced EMC Technologies help you create products that take full advantage of this wonderful material.

Contact us today to learn more!

by Sara McCaslin, PhD Sara McCaslin, PhD No hay comentarios

What You Need to Know about Spring-Energized Seals and Backup Rings

One of the common problems in high-pressure applications is extrusion of the seal into the extrusion gap. This will lead to a damaged seal, which could quickly prove both dangerous and expensive depending on the application. And this problem is not limited just to more traditional seal designs: spring-energized seals can also face problems with extrusion–which is why backup rings are sometimes needed in conjunction with a spring-energized seal.

Seal Extrusion

Extrusion becomes an issue when the pressure acting on the seal is greater than the extrusion resistance limitation of the seal or when there are operating conditions that reduce the seal’s extrusion resistance, such as high temperatures or moisture absorption. Extrusion is also a problem when guide rings or wear rings have increased the extrusion gap. BURs fit between the seal and the extrusion gap to prevent the seal from deforming and becoming caught in the gap.

And this issue is not limited to standard rotary shaft seals: it can also be a serious issue for spring-energized seals. If energized seals are failing and the edge of the sealing lip looks as if it has been “nibbled” on, there is a strong probability that the problem is seal extrusion–and a backup ring may be all that is needed to solve the problem.

Backup Rings

Backup rings (often abbreviated BUR or referred to as anti-extrusion rings) are used to prevent mission-critical seals from being damaged when they are continually exposed to high pressures and run the risk of extrusion. Backup rings prevent the seal from extruding or deforming by reducing the extrusion gap on the low-pressure side of the seal but do not serve as a seal themselves. 

Oklahoma Spring Energized Seal Company

Backup Rings with Spring-Energized seals

Materials used for BURs must be extrusion resistant themselves, which means they need to be hard. Like the seal lip, they also need to be resistant to the chemicals and environment to which they will be exposed to. Ideally, backup rings should also have low friction and excellent wear characteristics. There are several different materials used for backup rings, including polymers and elastomers. The most common polymers used include PTFE, PEEK, Nylon, and UHMW PE. For spring-energized seals, both PTFE and PEEK are often used

Filled PTFE (e.g., glass, carbon, etc.) can operate with pressures up to 5,800 psi. However virgin PTFE is limited to about 3,600 psi which means that for backup rings filled PTFE is preferred. PTFE has a maximum operating temperature around 575°F and it is very chemically resistant and has extremely low friction. It is also dry running and available in sufficient hardness for backup ring applications.

PEEK performs well at pressures up to 20,000 psi and has a maximum temperature operating temperature of 500°F.  It is also available will fillers to provide additional strength and hardness. Like PTFE,  PEEK is compatible with a range of chemicals, including many aggressive cleaning solutions. PEEK is often used with spring-energized PTFE seals.

Conclusion

If extrusion is the problem with a spring-energized seal, or you know that a seal design will run the risk of extrusion, then backup rings can be used to prevent extrusion. The use of backup rings not only extends the life of the spring-energized seal but reduces the probability of failure due to extrusion.

by Sara McCaslin, PhD Sara McCaslin, PhD No hay comentarios

Why PTFE Rotary Shaft Seals Are a Great Choice for Food Processing Applications

 

Food processing plant processing corn

While there are several options when it comes to approved polymeric or elastomeric seals for food processing applications, PTFE is one of the more popular choices–and that includes rotary shaft seals, as well.

Rotary shaft seals for food processing equipment have to do more than an ordinary seal:  they also need to withstand aggressive cleaning and sanitation regimens that may involve corrosive chemicals, be approved for contact with food, and offer effective, reliable performance. 

Where Shaft Seals are Used in Food Processing

Food processing machines that make use of shaft seals include mixers, food portioning equipment, dry product filling systems, ice cream dispensers, milk dispensers, high pressure homogenizers, water purification equipment, and distilled water pumps. They may be used with adhesives, flavorings, water, powders, preservatives, sauces, condiments, steam, and various fluids.

Operating Conditions

Rotary shaft seals for use in the food processing industry must  be able handle the standard operating conditions involved such as speed, temperature, and pressure. However, their operating environment can involve more than that: consideration has to be given to the type of media they will be exposed to (e.g., powders, extremely viscous fluids). 

PTFE is one of the polymers that has a proven track record with rotary shaft seals that have to function over a wide range of temperatures, pressures, and speeds, with various grades available that can offer more customized performance.

CIP/SIP

Rotary shaft seals must withstand the sterilization or cleaning procedures involved. CIP (Clean in Place), SIP (Sterilize in Place) and COP (Clean Out of Place) methods often require aggressive cleaning agents and/or superheated steam, powerful disinfectants, and potentially corrosive acids. 

PTFE is highly resistant to a wide range of aggressive chemicals, can handle repeated exposure to hot water and superheated steam, and will not react chemically to the powerful disinfectants and sanitizers that food processing equipment is exposed to.

Safe for Contact with Food

Any part of a rotary shaft seal that comes into contact with food must conform to the appropriate regulations, such as  FDA 21 CFR 177.1680, (EC) No. 1935/2004, and/or USP Class VI. Such approval is not easy to achieve: it takes into account whether the material releases any chemicals, tends to absorb moisture, goes through physical changes when exposed to high temperatures, reacts chemically to ingredients that are acidic, exhibits off gassing, and more. 

PTFE comes in grades that are fully compliant with regulations regarding contact with food and FDA approved, making it a safe choice for rotary shaft seals for food processing equipment. In addition, it is the most chemically unreactive polymer on the market today.

Conclusion

Finally, PTFE rotary shaft seals have proven themselves to be highly reliable, which is why you will see them used in dangerous, mission critical applications where safety and ruggedness is vital, such as those found in the oil and gas or aerospace industries. If you are looking for a FDA-approved rotary shaft seal for use in food processing applications, PTFE seals should be at the top of your list.

by Jackie Johnson Jackie Johnson No hay comentarios

The Automotive Industry During COVID-19

Like many industries, the automotive industry has been on a roller coaster of highs and lows during the coronavirus crisis.

With countries around the world struggling to regain traction, here is how some of the major players are doing.

China

During the beginning of 2020, there were concerns over a disruption in Chinese export parts. Total shipments during the first half of the year were down by 10%.

In response, June saw the Chinese government announcing its plan to increase the NEV credit ration by 2 percentage points every year until 2023, from 12% in 2020 to 14% in 2021, 16% in 2022 and 18% in 2023.

Europe

Europe has faced a large-scale interruption of productions during lockdown. Sales of vehicles also declined by 16% and car registrations have fallen to about 25%. This downturn has had a ripple effect in other European markets as well. The petrochemical market in particular has been heavily affected by the challenges faced by the European automotive industry.

However, with the easing of lockdowns in many countries in addition to various economic revival stimulus packages, Europe is once again seeing a growth in the auto industry.

United States

In the US, assembly plant closures have added to the already intense pressure on an increasingly distressed market, with limited inventory and fewer incentives continuing to hold back sales. Total sales for the first half of the year were down an average of 23%, with Toyota being hit particularly hard with a decrease of 24%.

There is hope, however. While still not at the same capacity as before the pandemic, Automakers like General Motors and Ford have been able to add shifts to their assembly plants. GM expects to rebuild their inventory to about 600,000 vehicles by the end of 2020.

Continuing Innovation

Despite the downturns and pitfalls this year has thrown, the automotive industry is not without its innovations. This year has seen a marked improvement in crash avoidance technologies. Toyota has partnered with Hebei Pride to commercialize its standardized safety testing for AEB (automatic emergency braking) systems, and Mercedes Benz has announced a new, frontal rear-seat airbags in all of their S class cars. In addition, the United States has passed the Moving Forward Act, which will mandate the inclusion of automatic collision warning technologies in all new passenger vehicles.

In Conclusion

While still bleak, things are slowly starting to look up for the global auto industry. As lockdowns ease up and companies are better prepared to keep employees safe, things are slowly starting to improve. The coronavirus pandemic has been a tough time for everyone, but if we continue to practice social distancing and continuing to innovate, we, regardless of the industry we are in, will get through this better than before.

Advanced EMC Technologies is dedicated to helping you during these uncertain times. Contact us to learn more!

by Sara McCaslin, PhD Sara McCaslin, PhD No hay comentarios

Spring Energized Sealing Solutions For Cryogenic Services in LNG Plants

LNG Plant

There are a limited number of reliable sealing solutions for cryogenic services in LNG plants, two leading polymers in use are spring-energized PTFE or UHMW seals.

Challenges of Working with LNG

Leaks involving LNG (Liquified Natural Gas) at cryogenic temperatures are dangerous to the health and safety of workers and to plant operation. Issues such as toxicity, extreme cold, asphyxiation, flammability, and explosions resulting from rapid expansion of LNG all point to the need for a reliable, leak-proof seal.

Finding an effective sealing solution for use in the cryogenic work environment of LNG plants can be extremely challenging. Keep in mind that nitrogen exists in liquid form under normal atmospheric pressure between -346°F and -320.44°F. It’s liquid to gas expansion ratio is very high at 1:694, which means as it boils (starting at its boiling point of -320.44°F) it will expand 694x its original volume. This can lead to an extremely high pressure change if it occurs in a sealed environment, and most LNG seals must remain functional at either vacuum pressures or extremely high pressures.

Cryogenic Seals for LNG Plants

The temperatures involved with LNG happen to lie where many elastomeric and polymeric materials lose their elasticity and begin to behave as brittle materials. Some seals will also experience dimensional fluctuations related to temperature changes, further increasing the probability of failure. If temperature fluctuations are cyclical, there are going to be problems related to cyclic stress. Yet another issue related to dynamic cryogenic seals is lubrication: at such low temperatures, standard lubrication solutions simply will not work.

The Options For Sealing are Limited two either UHMW or PTFE Polymers and a Full Contact- Anti-Shrink Spring is Essential.

Both seal jacket materials can be specified PTFE, often known by its trade names Teflon or Flourolon 1000. The Ultra High Molecular Weight PE or UHMW, Fluorolon 5000 can handle the low temperatures involved in cryogenic service without becoming brittle (some grades can handle temperatures as low as -350°F) or succumbing quickly to the effects of cyclical stress. In addition, both UHMW and  PTFE are self-lubricating, low friction, supports dry running, and is a non stick/slip material. In addition, both products are compatible with a wide range of chemicals, including those it would encounter in an LNG plant.

A spring-energized seal is a seal assembly that includes an energizing spring that forces the seal lip against the mating surface to achieve a highly leak-proof seal. This seal design, when combined with a PTFE lip, has been found ideal for cryogenic applications involving LNG.The spring energizer adds permanent resilience to the seal and is able to compensate for lip wear, eccentricity, hardware misalignment, and (perhaps most importantly when working with LNG) extreme pressures and dimensional changes. 

The recommended geometry for the spring energizer is a simple helical spring when cryogenic temperatures and either static, reciprocating, or rotary motion is involved. However, oscillatory or static motion may require the use of a solid spring. Recommended spring materials include  17-7 precipitation hardening stainless steel, 301/304 stainless steel, or, in some applications, Hastelloy, 316 stainless steel, Inconel, or Elgiloy.

Conclusion

The design of cryogenic seals for use in LNG plants can be challenging and must meet extremely high standards for reliability and safety, but PTFE spring-energized seals are an excellent starting point.

by Jackie Johnson Jackie Johnson No hay comentarios

PTFE Rotary Shaft Seals in High Speed Applications

PTFE Rotary Shaft Seals

The design and specification of rotary shaft seals is challenging enough, but things get even more complicated for high speed seals. High speed rotary shaft seals pose their own set of wear and heat generation problems that can make it difficult to select an appropriate lip material, but PTFE is up to the challenge.

Issues for High Speed Seals

In the context of rotary shaft seals, high speeds are often defined as those above 3,600 rpms. Such seals can be found in industries such as pulp and paper, wind energy, pumps, gear boxes, steel and aluminum processing, electric motors, medical devices etc.

High speed applications, such as those found in turbomachinery, can cause a seal to wear out faster and generate more heat because speed and friction do not get along well together. If the heat generated is sufficient, it can result in higher operating temperatures and changes to the geometry of the seal. And not all high-speed applications are compatible with lubricants, so in some cases the seal may need to be capable of dry running. It is also key that these seals do not exhibit stick and slip behavior at startup.

Requirements for High Speed Rotary Shaft Seals

High speed rotary shaft seal materials, in addition to the normal requirements for seals, must be …

  • abrasion and wear resistant (to reduce wear)
  • Dimensionally stable (to prevent changes in geometry due to high temperatures)
  • Thermally conductive (to dissipate heat generation)
  • High operating temperature (to account for heat generated during use)
  • Possess an extremely low coefficient of friction (to reduce heat generation and wear)
  • Reduced stick slip and breakout friction
  • Self-lubricating (for when lubricants cannot be used)

While there are several options available for seals that meet these requirements, one in particular stands-out: PTFE, or polytetrafluoroethylene.

PTFE High Speed Rotary Shaft Seals

PTFE exhibits several key qualities necessary for high speed rotary shaft seals. It has good abrasion and wear resistant properties, is dimensionally stable, and has good thermal conductivity. PTFE also has an operating temperature of up to 500°F and a melting point of almost 650°F. It also has the lowest coefficient of friction of any solid currently known to mankind, exhibits reduced stick slip, has an extremely low breakout friction, is self-lubricating, and can continuously operate as a dry running material.

PTFE also comes in various grades beyond virgin PTFE. It is available fillers such as Molybdenum Disulfide (MoS2) for increasing wear resistance, carbon for increasing wear resistance while keeping friction low, glass for better hardness and wear resistance, or various combinations of these. Keep in mind that there are also FDA approved seals for use in connection with pharmaceuticals and medical applications as well as food and beverage production.

PTFE rotary shaft seals are available in hydrodynamic, plain and multi-lip configuration and for situations where the production volume is low, they can be constructed from machined shells so there are no tooling charges.  At the same time, high production volumes can be manufactured from pressed shells to reduce unit costs.

Conclusion

For applications that demand reliable, long-lasting high-speed rotary shaft seals, PTFE is the engineer’s choice for reliable performance. It combines low friction, high operating temperatures, good wear properties, and dry running capabilities that can handle the rigors of high-speed applications.