Fluoropolymers in the Food Industry
by Jackie Johnson Jackie Johnson No Comments

Fluoropolymers in the Food Industry

High-performance fluoropolymers are incredibly vital for use in food and drink manufacturing industries. Setting them apart from general-purpose plastic such as PVC and PE, fluoroplastics enjoy a range of unique properties:

  • Thermal: Resistant to very low and very high working temperatures
  • Chemical: Total resistance to chemicals and solvents
  • Mechanical: Low friction, non-stick characteristics and tensile strength
  • Environmental: Resistant to weather, UV light and corrosion
  • Health: Non-toxic and high purity

Fluoropolymers such as PTFE (Polytetrafluoroethylene), FEP (Fluorinated Ethylene Propylene) and PFA (Perfluoroalkoxy Alkane) bring an abundance of benefits to the food and drink production, from cooking equipment to food coverings, conveyor belt rollers, UV lamp coatings, temperature sensor casing and non-stick surface covers. Because of this, fluoropolymers have kept products uncontaminated, workers safe and production running smoothly for years now.

In this week’s blog post, we will discuss the various ways the fluoropolymers are used in the food industry.

Beverage Dispensing

The requirement for a biologically harmless tubing product coupled with intermittent high temperatures over a long period of time present a challenge for hot beverage dispensing machines. Fluoropolymers such as PTFE and FEP are used as a tried and tested, FDA, NSF and EU compliant solution. Build of residue is greatly reduced due to the smooth internal surfaces provided by fluoropolymer materials. Not only are they FDA compliant, but they are low maintenance as well!

Food Packaging

In packaging and processing food, it is extremely important that the materials used are safe. As such, fluoropolymers such as PVDF, or Polyvinylidene Fluoride Fluoropolymer, are highly regarded in the food packaging industry for a variety of reasons. First, they are incredibly stable materials, and highly resistant to most chemicals, mineral acids, organic acids and other food preservatives. In addition, they are non-toxic and resistant to bacterial and fungi growth.

PVDF is particularly useful in food processing industry due to its unique chemical resistance when temperatures go as high as 300 degrees Fahrenheit (or around 149 degrees Celsius).

PTFE Coatings

With the invention of PTFE, also known as Teflon, non-stick and low friction coatings have played a vital role across the food industry.

For years, PTFE has been used as a coating for cooking applications where particularly sticky or abrasive products are used, such as commercial waffle irons, bread pans, mixers and beaters, hoppers, dough rollers and blades. This allows them to function much more effectively, and the use of oils or other release agents can be substantially reduced or even eliminated.

With ease of use also comes ease of cleaning, and PTFE coating can reduce the intensity and frequency of the cleaning process. It also acts as a hygienic barrier between the food and the surface of the component. These combined save significant employee time and effort, which ultimately reduces labor costs, saving both time AND money.

Belt Conveyors

In the cooking and food processing industries, belts and conveyers made with PTFE coatings are used for mass-produced foods such as bacon, chicken, hamburgers and eggs.

Because of its nonstick properties, the PTFE coating allows food to easily come off, with little mess. This facilitates a high volume of production for commercial food processors.

Industrial Bakeware

Fluoropolymer coatings assure high-quality coating solutions for bakeware used by industrial bakeries. This helps bakeries not only drive efficiency, but also improve the hygiene and safety of their operations. It also improves the quality of the final baked product, with less waste and less butter and/or grease used to keep the product from sticking to the pan.

Home Cookware Manufacturing

We have talked about how fluoropolymers are across the commercial industry, but they are just as equally prevalent in our homes as well.

The use of nonstick pans has been popular in homes since the 1950s, when a French engineer begun coating his fishing gear with Teflon to prevent tangles. His wife then suggested using the same method to coat her cooking pans. In 1956 the Tefal company was formed and began manufacturing non-stick pans.

And nonstick cookware is popular to manufacture as they can be machined and coated relatively easily.

Other Uses

As discussed, fluoropolymers have many uses in the food industry, and many more that we did not cover. Some of these include

  • Shatterproof Coatings for Heat Lamps
  • Encapsulated Temperature Sensors
  • FEP Roll Covers
  • Laser Marked and Printed Tubes for Identification
  • And more!

In Conclusion

With the strength and versatility of fluoropolymers, it is no wonder that it is such a popular material within the food and drink industries.

Because of its high temperature and chemical resistance, nonstick and non-toxic surface, many health organizations have recognized it’s inherit value and, as such, have made fluoropolymers the gold standard within the food industry.

To learn more about fluoropolymers, visit our page by clicking the link here. And if you need PTFE sealing solutions, contact us today!

The Benefits of Labyrinth Seals | Advanced EMC Technologies
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Benefits of Labyrinth Seals

The term “labyrinth” conjures up images of elaborate mazes, and in the context of seals that really isn’t far from the truth. They are a fascinating use of fluid dynamics to prevent contaminant intrusion in an extremely effective manner. And these seals are used in everything from basic machine spindles to cryogenic turbopumps for rockets. There are many benefits of labyrinth seals. 

A labyrinth seal is a specific type of dynamic mechanical clearance seal that utilizes a maze-like cross section to create areas of turbulence to prevent contaminants from making their way in and fluids from making their way out. They also reduce the clearance that is available for particles to enter. Labyrinth seals are most typically used to isolate an area of high pressure from an area of low pressure, but they work well in other applications as well. 

In this week’s blog post, we will discuss the many benefits of labyrinth seals, their applications, and more!

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Why Geckos Can't Climb PTFE
by Jackie Johnson Jackie Johnson No Comments

Why Geckos Can’t Cling to PTFE

It may come as a surprise to some but geckos are not, in fact sticky! Gecko’s can cling to glass and climb up walls, but geckos are not inherently adhesive. In fact, there are certain surfaces geckos can not cling to at all- mainly PTFE.

In this week’s blog post we will go over exactly how the gecko gets its Spiderman like abilities, and why exactly they can not seem to climb on PTFE.

A Sticky Situation

With certain types of geckos, their feet contain thousands of tiny, hair-like, hierarchical fibrils called setae, that end in even more, microscopic hair-like structures, so tiny they are not much larger than the wavelength of visible light.

These setae are also ultra-flexible, so when a gecko jumps to another surface, they are able to absorb an incredible amount of energy and redirect it, allowing the gecko to quickly cling from surface to surface.

There are two prevailing theories as to how this process works. One is known as van der Waals forces, or molecular attractions that operate over very small distances. The other, proposed by Yale research Hadi Izadi is that geckos use static electricity which allows them to cling to most surfaces.

Most surfaces except, it seems, Teflon.

Teflon – The Bane of Geckos?

Did you know that PTFE was engineering specifically to resist adhesion by van der Waals forces?  PTFE is composed of carbon and fluorine atoms.  Of all the elements known to date, fluorine has the highest electronegativity.  This causes PTFE to repel other atoms that come near it.  More specifically, it works against van der Waals forces.

Furthermore, the molecular structure of Teflon is such that the fluorine atoms surround the carbon atoms.  It repels any atoms that try to come near the carbon atoms, giving PTFE its outstanding chemical inertness.

Researchers at the University of Akron, in an effort to further understand, and hopefully replicate, gecko stickability, decided to see what kind of surfaces geckos can cling to, and Teflon was one of the materials tested.

The answer?

Because of its ability to resist adhesion by van der Waals forces- geckos, who potentially use van der Waal forces to cling to other materials, cannot cling to dry PTFE surfaces.

In Conclusion

So, it would seem that the very mechanisms that prevent geckos from walking up dry PTFE provide its most attractive characteristics: extremely low friction and high chemical resistivity.  So, when you are looking for a low-friction option for a bearing or seal, don’t forget the bane of gecko’s everywhere: PTFE.

Amcor Partners with Michigan State University
by Jackie Johnson Jackie Johnson No Comments

Amcor Partners with Michigan State University

Michigan State University’s School of Packaging is getting an upgrade thanks to global packaging leader Amcor Ltd. Thanks to Amcor, the school is receiving more than 10 million in US dollars to go towards funding a packaging sustainability professorship at the school, as well as upgrading the programs building, which has not been upgraded since 1987. And as Amcor partners with Michigan State University, both the school and the company hope to create a more sustainable plastics packaging industry.

In this week’s blog post, we will discuss the various upgrades the school is getting, the professorship and the building renovation.

Packaging Beginnings

The program at MSU was started in the fall of 1952 as a discipline in the Department of Forest Products, with the first Bachelors of Science degree in Packaging awarded in March 1955. In 1957, the MSU Board of Trustees separated the Packaging curriculum from Forest Products and, with industry assistance and advice, established an independent School of Packaging.

By the late 1960s enrollment in the program. had risen to about 300 students. With that many students, new facilities needed to be built, and in 1964 the original Packaging Building was completed with funds from corporate and private donors. Major additions to the building were completed in 1986 after student enrollment peaked at a whopping 1000 students.

Today, the School has earned a world-wide reputation for leading the charge in packaging design, innovation and sustainability.

Amcor’s Transformative Gift

In August, plastic packaging company Amcor made a $10.8 million dollar donation to MSU’s School of Packaging. The reason, according to Amcor, is manyfold.

“Today, we have over 100 MSU graduates working at Amcor already.” Said David Clark, vice president of sustainability for Amcor. “We see this as an opportunity to make a long-term commitment toward developing a stream of talent, not just for our company but also the industry.”

Amcor also has the benefit of close proximity to MSU. Amcor Rigid Packaging is based in Ann Arbor, MI, while Amcor Flexibles North America is based near Chicago, IL, both mere hours away.

“The ability to have somebody close by who is advancing the thinking about more sustainable packaging and more sustainable packaging systems is something we’re really excited about,” Clark said.

Transforming the Packaging Program

With the money, MSU plans to bring on board an endowed chair, a professorship paid for by the endowment provided by Amcor, for sustainable packing.

“The endowment for a faculty position for sustainability and the circular economy,” said Matt Daum, director of the MSU School of Packaging, “represents Amcor’s shared commitment with MSU to excellence and innovation in the future of packaging.”

While half of the money will be going to the endowed chair, the other half will go to upgrade the school’s existing building on the MSU campus.

The building, which, as stated earlier, was last renovated in 1986, is due for an upgrade. Teaching methods have changed drastically since the 80s, and a portion of the money is set to renovate the building’s main classroom, that seats a mere 100 in a slightly outdated auditorium/stage setting.

According to Daum, MSU plans to transform it into a flexible learning area, with a level floor, movable furniture and the ability to use a variety of technologies including laptops, smartphones and smartboards.

The construction will also focus on other building renovations such as more office space for faculty, more laboratories and, eventually, more classroom spaces.

“…we want it (the building) to be inspirational”, said Daum, “to be a hub where this becomes the place to draw the best minds for packaging and business leadership to come and think though and innovate in the packaging sustainability area.”

Planning for a Bright Future

The partnership between Amcor and MSU is certainly exciting. With the collaboration, both Amcor and MSU hope to lead the way to creating solutions that effectively manage used plastics. Clark is particularly enthusiastic about the partnership and what it means for the future.

“We hope it inspires other companies to make similar contributions to both academics and other collaborations that are going to help our industry move forward with solutions,” he said.

With nearly 10,000 MSU packaging school alumni around the world, Daum also hopes that school alumni will learn of the upgrades and contribute to the future of the program.

And as more and more students graduate, Amcor is excited for the innovation and ground-breaking advancements they will bring, creating a more sustainable industry as a whole.

For more plastics industry news, visit our blog HERE. For polymer seals, bearings and more, contact us today.

Benefits of Spring-Energized Seals for Wind Turbines | Advanced EMC Technologies
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Benefits of Spring-Energized Seals for Wind Turbines

According to Statista, installed wind power worldwide reached a cumulative capacity of almost 743 GW (gigawatts) in 2020 and is expected to reach almost 841 GW by 2022. As it remains a competitive source of renewable energy, engineers are looking for ways to enhance the efficiency and reliability of wind farms and the turbines that comprise them. One design aspect under consideration is the seals that are used in these turbines. This week, we will discuss the various benefits of spring-energized seals for wind turbines. 

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Fluoropolymers for Injection Molding | Advanced EMC Technologies
by Jackie Johnson Jackie Johnson No Comments

Fluoropolymers for Injection Molding: Challenges and Solutions

Fluoropolymers are used in many different industries and applications, ranging from medical devices to oil and gas. Engineers often assume that just because a part is to be manufactured from a fluoropolymer that it cannot be injection molded, but that is not correct. Fluoropolymers are not just limited to manufacturing processes such as machining, compression molding, or sintering. 

What Are Fluoropolymers?

A fluoropolymer, as the name implies, is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. Fluoropolymers are known for certain characteristics such as …

  • Very low friction
  • Non-stick
  • Excellent performance in high temperatures
  • High purity and non-toxic
  • Aging is minimal
  • Easy to sterilize
  • Excellent resistance to acids, bases, and solvents
  • Also resistant to microbiological and enzyme attack
  • Good electrical insulating properties

Commonly Used Fluoropolymers

The most commonly used fluoropolymers include …

  • ECTFE (ethylene chlorotrifluoroethylene), trade name Halar
  • ETFE (ethylene tetrafluoroethylene), trade names FluonETFE, Neoflon, and Tefzel
  • FEP (fluorinated ethylene propylene), trade names Dyneon FEP, Neoflon FEP,  and Teflon FEP
  • FPM/FKM (fluoroelastomer), trade names Viton, Tecnoflon FKM, DAI-EL, and Fluonox
  • PFA (perfluoroalkoxy alkane), trade name Chemfluor, Hostaflon PFA, and Teflon PFA
  • PTFE (polytetrafluoroethylene), trade name Teflon
  • PVDF (polyvinylidene fluoride), trade names Hyldar, KF, Kynar, and Solef
  • PVF (perfluoroalkoxy), trade names Teflon PVF, Fluon PVF, and Dyneon PVF

Only some of these fluoropolymers have the properties that allow them to be injection molded. What makes the difference is whether they are melt processable.

Melt Processable Fluoropolymers

For a fluoropolymer to be injection molded, it must be melt processable. And while some materials like PVF may offer excellent properties, they cannot be injection molded. . However, PFA, FEP, PVDF, ETFE, ECTFE, and PCTFE are melt processable and can be injection molded. PTFE can also be injection molded, but it takes an extremely high level of skill and specialized equipment. In fact, just because a fluoropolymer can be injection molded does not mean there are not major challenges.

Common Issues With Injection Molding Fluoropolymers 

Injection molding offers a host of benefits in manufacturing and is a popular choice for a wide variety of components. However, there are certain problems that must be addressed for fluoropolymer injection molding, including high melt temperature, high melt viscosity, high shear sensitivity, and fluorine outgassing.

High Melt Temperature

A very high melt temperature is required to work with fluoropolymers, and the injection molding equipment and molds may reach temperatures up to 800°F. Hot runner systems are also needed, and careful attention goes into the design of runners and gates to encourage even flow of the material. However, the temperatures must remain controlled to avoid degrading the fluoropolymers.

High Melt Viscosity

Another complication lies in the fact that fluoropolymers such as PFA have a high melt viscosity, which is related to how flexible the polymer chains are as well as their degree of entanglement. Polymers that have a high melt viscosity flow very slowly even in their melted form and the melt can actually fracture if it encounters sharp edges or gates and runners that are too small.

High Shear Sensitivity

Another challenging aspect of injection molding a fluoropolymer is their high shear sensitivity. A material that exhibits shear sensitivity changes its viscosity when subject to stress or pressure, which is a problem. The viscosity of the polymer melt will vary significantly as it goes through the various stages of injection molding.

Fluorine Outgassing

Fluorine outgassing occurs when these polymers are melted, presenting another issue because of the corrosive effects of fluorine gas on barrels, screws, nozzles, runner systems, and molds. To make matters more complicated, fluorine gas is also highly toxic. 

Solutions for Injection Molding Fluoropolymers

Solutions have been developed to address the challenges involved with fluoropolymer injection molding, starting with thermal management. 

Thermal Management

Managing the temperature of the polymer melt as it passes through the various stages in the injection molding is vital to keeping the polymer flowing predictably. It also helps to ensure the integrity of the final part by preventing degradation of the polymer melt. The different zones and points have specific temperatures at which they should be kept and this requires highly precise thermal management. 

Gate, Runner, and Mold Design

While any injection molded part requires careful design of the gate, runner, and mold, this is especially important in the context of fluoropolymers. Depending on the fluoropolymer being processed, there are certain key dimensions for gates, hot runner systems, and the mold cavity. There also exist recommendations for the gating systems, such as whether tunnel, sprue, or fan gating should be used. In addition, careful design is needed to prevent issues with melt fracture.

Corrosion Resistant Materials

Barrels, screws, nozzles, runner systems, and molds must be made from materials that are corrosion resistant. The materials for these components have to possess excellent high-temperature material properties including hardness and wear resistance. Ther barrel, screw, and nozzle must be manufactured from special materials. 

For example, barrel material options include IDM 260, Xaloy 309, and Wexco B022 often work well. Effective screw materials are usually certain grades of  Inconel and Hastelloy as well as Haynes 242 alloy. For the nozzle tip there are Hastelloy grades that provide the needed properties.For the molds, materials such as plated tool steel or nickel alloys possess the needed corrosion resistance, thermal performance, and wear properties. 

Venting

Fluorine outgasses can be managed with proper venting, but the materials for the vent must be extremely corrosion resistant. Furthermore, the vents must be kept very clean. In addition to the danger of outgassing, gas trapped within the mold must also be addressed in order to avoid part defects and reduce the maintenance required to keep the molds ready to use.

Conclusion

There are certain fluoropolymers that can be injection molded, but certain issues must be addressed to successfully manufacture parts of the quality and integrity needed. And while there are many companies that are good at injection molding parts, not all of them have the equipment and experience to injection mold fluoropolymers. 

Here at Advanced EMC, we have the equipment and skill to successfully manufacture fluoropolymer parts through injection molding. In fact, we offer engineering assistance to help you select the best type and grade of material and configure your parts to make them as manufacturable as possible. Our injection molding machines range from 75 to 500 ton and we have a Class 100,000 clean room if needed. Contact us today for all your fluoropolymer needs. 

Spring Energized Seals in the Food and Dairy Industries | Advanced EMC Technologies
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring Energized Seals in the Food and Dairy Industries

The food and dairy industries are tough on seals, whether it is extreme pressures and temperatures or the limitations posed by using only FDA-approved materials. Spring-energized seals, however, can prove an excellent solution for the challenges posed by these industries. In this week’s blog post, we will discuss spring energized seals in the food and dairy industries.

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Most Common Questions about Canted Coil Springs } Advanced EMC Technologies
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Most Common Questions about Canted Coil Springs

Here are answers to seven of the most common questions asked about canted coil springs.

Where Are Canted Coil Springs Used?

Canted coil springs can be used in many different ways, but many are not aware of exactly how versatile they are. In the medical industry, they are used to shield equipment from crosstalk that could compromise the integrity of data. The automotive industry depends on canted coil springs to achieve solid mechanical and electrical connections while reducing weight and minimizing the complexity of assemblies. 

In the oil and gas industry, they are used to achieve both electrical and mechanical connections in the rugged environment of downhole tools. Canted coil springs protect sensitive equipment from lightning strikes in the aerospace industry. And those are just a few examples of how they can be used.

What is a Canted Coil Spring?

Traditional springs have all the coils perpendicular to their longitudinal axis. Canted coil springs, on the other hand, have the individual coils parallel to each other and at an angle to the longitudinal axis. Because of how the coils are oriented, these springs can effectively serve a wide range of uses that traditional springs cannot.

Are There Any Other Names for a Canted Coil Spring?

Yes, as a matter of face there are. Canted coil springs are also called slant coil springs and cant coil springs, both in reference to the angle (or cant) at which the coils are parallel to each other.

What Makes a Canted Coil Spring Special?

Because of the cant of the coils, these springs have a flat load curve when compressed–which is rather unusual for a spring. This means that the load generated as these springs are compressed is predictable through their wide deflection range. 

What Can Canted Coil Springs be Used For?

Canted coil springs have four specific areas of application in which they excel: energizers for spring-energized seals, mechanical connectors, multi-point electrical connectors, and EMI/RF shielding.

Spring-Energized Seals

Canted coil springs are one of the options when specifying a spring-energized seal. Spring-energized seals provide outstanding performance in spite of issues such as uneven mating surface,  hardware gaps, runout, eccentricity, out of roundness, and seal lip wear. 

In that context of spring-energized seals, canted coil springs generate a flat load curve that in turn keeps friction at a predictable, constant level. This is extremely important in sealing applications for which friction and torque are critical to the functionality of a seal. In addition, canted coils do not experience compression set. Canted coil spring energizers work best when there are moderate to high speeds involved and are ideal for situations where friction needs to be highly controlled.

Mechanical Connectors

First, canted coil springs work well for latching, or fastening two parts together so they can still be disconnected when needed. They also work extremely well at locking, where two parts are permanently “locked” together. Holding is another task for which canted coil springs excel: two parts can be aligned and retained, but with sliding possible. Sliding is highly controlled by spring force generated when the canted coil spring is deformed.

In this type of application, canted coil springs can be fine tuned to achieve highly specific insertion and removal forces. This is made possible by the nearly constant spring force that these springs generate over their deformation range.

EMI/RF Shielding

One of the more interesting applications of canted coil springs is their ability to provide EMI/RF shielding.  Their electrical properties can be adjusted to meet specific impedance requirements to achieve optimal shielding for certain ranges of interference, including both conductive and radiated. And they work extremely well at shielding from crosstalk.

These springs can easily adapt to even the most uneven and irregular shapes, allowing them to provide a consistent level of shielding, and can be used with connect/disconnect assemblies, waveguide flanges, rectangular electronics enclosures, and both radial and coax connectors.

Multi-point Electrical Conductors

Canted coil springs can also serve as multi-point electrical conductors. Because surface area provided by the canted coils, they provide a cooler operating temperature which can be critical in certain designs, including those where space is highly limited. Canted coil springs can serve as both conductors and grounds, in both static and dynamic applications. Their multi-point contact system means they can keep electrical contact even in extremely harsh conditions, including those where vibration and shock are common. 

What Kind of Materials Are Canted Coil Springs Available In?

The three most common materials for canted coil springs are:

  • Hastelloy
  • Inconel
  • Elgiloy
  • 300 Series Stainless Steel (e.g., 316, 316L, 302)
  • Copper alloys

In addition, they can be nickel, silver, or gold plated if needed. 

If there is going to be extremely high temperatures and/or exposure to corrosive media, Elgiloy is typically recommended. For shielding or use as a multi-point conductor, stainless steel and copper alloys work extremely well.

What Kind of Options Are Available for Canted Coil Springs?

The basic options for canted coil springs outside of those related to materials are …

  • Wire diameter
  • Coil size (width and height) 
  • Coil cant angle 
  • Number of independent coils
  • Inner and outer diameter of the spring

By adjusting these parameters and material selection, specific performance goals can be achieved.

Conclusion

Canted coil springs are useful in so many different applications, and their performance is fully proven in the field. Whether you need highly reliable spring-energized seals for use in vacuum conditions, locking components for orthopedic implants, a way to protect rectangular electronics enclosure from a specific range of interference, or a multipoint conductor that also serves as a latching connector, canted coil springs are an excellent option.

And remember that Advanced EMC offers FlexForceTM canted coil springs. Our engineers can work with you to find the right combination of characteristics and properties to meet the needs of your application. Contact us today!

 

Spring-Energized Seals for the Medical Industry
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring-Energized Seals for the Medical Industry

Spring-energized seals, when designed correctly, provide a highly-reliable sealing solution for medical applications where failure can be fatal. Selecting the right seal jacket material and energizer is critical, but also complex. In this week’s blog post, we will discuss spring-energized seals in the medical industry, the best materials, how they are used, and more!

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Best Materials for Spring Energized Seals | Advanced EMC Technologies
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Best Materials for Spring Energized Seals

The polymers most commonly used in spring-energized seals are PTFE, PEEK, UHMW PE, Vitron, and Hytrel. All of these are high-performance engineering polymers, but some are better adapted for certain applications than others. In this week’s blog post, we will discuss the best materials for spring energized seals, and how they can be applied for each industry. 

Spring-Energized Seals with Polymer Jackets

Polymer sealing jackets are often chosen over their rubber counterparts for various reasons, including better performance at extreme temperatures, a wider range of chemical compatibility, and lower friction. And, depending on the material under consideration, polymers often provide better specific strength and stiffness. Because of these and other properties, they are often used as the sealing jacket for spring-energized seals.

However, knowing which polymer is best adapted for a specific application can be challenging, especially since there are a wide range of engineered polymers that offer excellent mechanical and chemical properties. What follows is a discussion of the most popular spring-energized seal materials for five industries.

Food and Dairy 

Food and dairy applications can make the design of spring-energized seals more challenging, especially when it comes to the choice of the seal jacket material. Materials must be compliant with FDA CFR 177, contained in Title 21 of the Code of Federal Regulations. And other standards may also apply, such as NSF/ANSI standard 61 for drinking water systems,  3A Dairy sanitary standards 18-03 and 20-27, and (EU) 1935/2004.

Because of such regulations, the two most commonly used jacket materials for spring-energized seals in the food and dairy industry are PTFE (both virgin and certain grades of mineral-filled) and UHMW PE (Ultra High Molecular Weight Polyethylene). Besides their FDA approval, these materials also provide low friction, compatibility with most cleaning and sanitation routines, and a good range of operating temperatures. In addition, both materials are self-lubricating, which eliminates the problem of finding a lubricant that is safe to use.

Aerospace and Defense

Aerospace and defense applications that require a spring-energized seal often turn to materials such as PEEK (Polyether ether ketone)  and PTFE. Spring-energized seals are used with hydraulic systems, fuel systems, actuators, and gimbal pods in everything from massive airliners and space rockets to lightweight, nimble drones. Operating environments may involve extreme temperatures, exposure to aggressive chemicals, and mission-critical performance. Some operating conditions may also involve cryogenic temperatures, for which PTFE and Hytrel work extremely well. Note that Hytrel is a TPC-ET thermoplastic polyester elastomer.

In space applications, temperatures can range from cryogenic vacuum conditions to extremely high temperatures and pressures. For spring-energized seals used in rockets, PTFE is the most common due to its wide operating temperature range, outstanding chemical compatibility, and extremely low friction. In addition, PTFE lends itself to the weight constraints and pressure fluctuations involved with space travel, and has been proven over and over that it can provide mission critical levels of reliability.

Automotive

Automotive seals must withstand rugged, extreme environments that may involve everything from corrosive chemicals to extremely high temperatures. When selecting a seal material for automotive applications, properties such as low friction, wear resistance, resistance to abrasion, and durability are major concerns. 

For automotive applications, the most common choice of seal jacket material for spring energized seals include PTFE and Viton (fluoropolymer elastomer). To provide the best performance in the demanding environment of automotive seals, additives such as MoS2 (Molybdenum Disulfide) or carbon may be added to increase strength, wear resistance, and stiffness or achieve low friction.

Renewable Energy

One of the most common areas in renewable energy that requires the use of spring-energized seals is wind energy. Seals for wind turbines can be extremely challenging to design because of the wide range operating temperatures involved, problems with lubricants that can freeze in cold temperatures, extremely low friction so that energy is not wasted, and reliable performance over a long life. Seals must also exhibit low moisture absorption. 

Wind turbine seals typically use PTFE and UHMW PE, known for their low friction and self-lubricating properties. They also offer extremely low moisture absorption, a good range of operating temperatures, and good wear resistance. In addition, they have good resistance to degradation under constant UV exposure.

Oil and Gas

In the context of the oil and gas industry, LNG plants figure heavily in applications that require the use of cryogenic spring-energized seals. For such cryogenic applications, PTFE and UHMW PE have been found extremely effective. For non-cryogenic environments, Hytrel (thermoplastic polyester elastomer) is another commonly used material along with PTFE. These materials offer good performance in sub-freezing temperatures and are reliable enough to support the spring-energized seal design as it prevents leaks that could be devastating not just to humans but to the environment as well.

For other applications, issues of extremely high temperatures and pressures are involved, such as sealing solutions for wellheads. For those jobs, PEEK is often the preferred material. It possesses low friction, excellent chemical compatibility, a wide operating temperature range, and high strength. In addition, it is also one of the few polymers that can maintain its performance in sour gas environments.

Conclusion

Spring-energized seals can provide gas-tight, highly reliable sealing solutions for some of the most difficult operating environments imaginable when combined with the right material. For many sealing solutions out there, high performance polymers are a perfect complement to the ruggedness of a spring-energized seal in many different industries. If you need a spring-energized seal, regardless of industry, we can help you select the right material to provide a durable, effective seal. Contact Advanced EMC today!