4 Key Benefits of PTFE Energized Seals for the Aerospace Industry

PTFE energized seals have found a multitude of applications in the aerospace industry.  

There are many reasons for the use of PTFE in aerospace. It offers excellent strength, extremely low friction, toughness, dimensional stability, and abrasion resistance. When combined with a spring-energizer, it provides a combination of properties and characteristics that work very well in the aerospace industry.

PTFE Seals and Aerospace

PTFE seals can be found in flight controls, jet engines, airframes, air management systems, and fuels systems. This includes commercial, military, and space applications. PTFE energized seals can be used in engine cooling lines, auxiliary power units, cabin pressure systems, compressor seals, turbine seals, pumps, fuel injectors, hydraulic controls, and more.

1.  Low Friction

One of PTFE’s most outstanding characteristics is extremely low friction. It is self-lubricating and can be used in dry-running applications without a problem.  PTFE also does not exhibit problematic stick-slip behavior. These features also reduce power and torque requirements, while increasing overall efficiency.  

2.  Extreme Temperature Performance

Aerospace applications often involve extreme temperatures, and PTFE is made for extreme temperatures. It can handle a wide range of temperatures, with a maximum continuous operating temperature of 550°F down to cryogenic temperatures like -450°F.  In addition, it remains extremely stable even at high temperature while retaining its flexibility at low temperatures.  PTFE is also nonflammable and has a UL 94 Flame Rating of 94 V-0.

3.  Extreme Chemical Inertness

PTFE is one of the most chemically compatible polymers on the market today.  It will not contaminate any sensitive media it comes into contact with, and is non-soluble. This makes it ideal for the aggressive chemicals encountered in aerospace applications, including jet fuels, degreasers, and hydraulic fluids.  Its primary weakness is alkali metals.

4.  Wide Pressure Range

Aerospace seals typically need to operate under extreme pressures, often ranging from 20 ksi to vacuum pressures.  Note that there are blends of PTFE specifically for high PV applications such as those encountered in aerospace applications.  It is also known for its excellent compressive strength.

Other Excellent Qualities

Another key aspect of PTFE spring energized seals is the incredible wear properties that PTFE possesses.  It also exhibits very, very low water absorption due to its hydrophobic nature, which also makes it easy to clean. PTFE is compatible with a variety of fillers that can improve its various properties so that it can be better tailored to meet design needs.  It also offers excellent stiffness and outstanding dimensional stability.

Power of Spring-Energized PTFE Seals

PTFE has excellent characteristics for aerospace applications, from its wide range of both operating pressures and temperatures to its chemical resistivity and dimensional stability.  When such properties are combined with its ease of manufacture and its performance in extreme environments, it’s easy to see why PTFE energized seals are a first choice for many aerospace engineers.
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5 Reasons Why PTFE Seals are an Excellent Choice for Automotive Applications

Automotive PTFE Shaft Seals

In this article, we are going to explore the reasons why PTFE seals are among the best choices for many automotive applications.  You’ll find PTFE seals in fuel cell seals, fuel injection pumps, steering wheel seals, air conditioning, compressor seals, hydraulic seals, and more.  We’re going to focus our attention on PTFE shaft seals.  Let’s take a look!

Reason #1:  Low Friction

PTFE shaft seals have unbelievably low friction and are long lasting, keeping the fluids where they are supposed to be.  They are also capable of dry running, since they are self-lubricating and don’t require additional lubrication in order to perform well.

Reason #2:  Chemically Resistant

PTFE rotating shaft seals also perform extremely well in the presence of automotive fluids, including fluids and chemically aggressive oils.  They are regularly used with diesel and gasoline, as well as alternative fuels.  In fact, PTFE seals are among the most chemically resistant polymers on the market today. 

Reason #3:  Performance at High Temperatures

At high temperatures where other seals may begin to fail, PTFE dynamic shaft seals keep going strong.  They retain their performance characteristics even at abusive temperatures up to 600°F.  This includes their stiffness, strength, chemical resistance, low friction, dimensional stability, and durability.

Reason #4:  Survival at High Surface Speeds

PTFE dynamic seals work extremely well for demanding high surface speed applications because of their resistance to the effects of heat and their ultra-low friction characteristics, performing much better than their elastomeric counterparts.

Reason #5:  Reduction in Vehicle Emissions

Because of the reliable sealing power of PTFE, automobiles that make use of PTFE seals typically have lower vehicle emissions and CO₂.  This is a powerful combination in a modern automotive industry where federal oversight and regulations are pushing toward more eco-friendly vehicles.

High Performance PTFE

PTFE rotary shaft seals are an increasingly common sight in the automotive industry, and far more reasons than just their low friction, chemical resistance, performance at high temperatures, survival at high surface speeds, and reduction in vehicle emissions.  If you are looking for a high performance, durable, reliable seal, don’t forget to check out PTFE.
Tags:PTFE,teflon ptfe,seal

4 Reasons: PTFE Rotary Shaft Seals for Low Friction High Speed Applications

PTFE rotary shaft seals are an excellent solution to high speed applications with surface speeds up to 30 m/s.  In this article, we are going to look at four reasons behind that continued popularity. 

Reason # 1 Low Friction

PTFE, also known as Polytetrafluoroethylene or by its trademarked name Teflon, has one of the lowest coefficient of friction of any solid known to mankind, even when in contact with metal.  It’s usually estimated at 0.05 to 0.10 for virginPTFE. Because of this extremely low friction, in many rotary applications there will be significantly less frictional drag when compared to options, such as conventional rubber shaft seals.

Reason # 2 Film Transfer

When PTFE rubs against a hard surface, it transfers a microscopic layer to that counter surface.  This contributes to its extremely low coefficient of friction.  Here’s how engineers and scientist describe the process:

1. The molecules on the contacting surface of PTFE are deformed due to applied forces acting at that surface.
2. The molecules begin to stretch along the direction of the sliding motion.
3. Because of the weak intermolecular forces, PTFE molecules are transferred to the counter surface in a film between 50 to 200 Angstroms thick.
4. As a result, PTFE is now sliding on PTFE instead of directly on the counter surface.

Reason # 3 Dry Running

Another awesome feature of PTFE is its ability to perform without additional lubrication.  PTFE is actually classified as a self-lubricating polymer.  It offers reduced stiction and breakout friction, which can be key for many rotary applications. 

Reason # 4 Chemical Resistivity

Another facet of PTFE that makes it popular as a shaft sealing material is its chemical resistivity.  The list of chemicals that can attack PTFE is short, and primarily consists of alkali metals, such as elemental sodium, and rare fluorinated solutions.  This chemical inertness is said to be a result of carbon-fluorine bonds in PTFE.

Another interesting facet of PTFE is its hydrophobic behavior, whereby it repels water and water-containing substances.  The hydrophobic behavior aids in its chemical inertness, and also makes it easier to keep clean.  This behavior due in part to the high electronegativity of fluorine.

CONCLUSION:

Of course, there are more reasons behind the popularity of PTFE for rotary shaft seals in high speed applications.  PTFE has an extended shelf life, can perform at both cryogenic and extremely high temperatures, and is known for its easy installation.  However, the main reasons are its low friction, film transfer, dry running, and chemical resistivity.

So, the next time you need a rotary sealing solution that involves high speeds and low friction, check out PTFE rotary shaft seals.  They might be just the solution you are looking for.

Tags:ptfe teflon,teflon,seals

PTFE Guidewire Application Process Eliminates Delamination

Solution proven to have no PTFE delamination for 34,000,000+ guidewires.

The guidewire coating delamination problem reached catastrophic proportions late last year. In October, Medtronic—a major guidewire supplier—recalled over 84,000 units that had the potential for the PTFE coating to flake off. But Medtronic was not alone; other manufacturers have recalled guidewires, too.

These were FDA Class 1 recalls, meaning these guidewires and microguidewires represented serious health risks in which the applied coating—PTFE in this case—had the potential to delaminate or flake off. If this occurs before or during a medical procedure and even a microscopic flake enters the patient’s bloodstream, the results can be serious, including blood clots, stroke, heart attack, tissue necrosis, and even death. Between January 2014 and November 2015, the FDA received approximately 500 Medical Device Reports—including reports of nine deaths—attributed to PTFE coating delaminating from guidewires.
 

The medical ramifications to the patient and their family are undeniably devastating. For the guidewire manufacturer, the results can also be catastrophic. Based on other comparable recalls, the device manufacturer will take a substantial hit to their reputation and see their stock prices and market cap often falling 10 percent from a single incident.
 

Further, there is the matter of unresolved liability. Defending a lawsuit stemming from blood clots, stroke, or death resulting from a faulty guidewire would undoubtedly be a costly endeavor, and the damages available to the patients and their families can be significant. There is no set benchmark for the types of damages available in these cases, particularly when the damage done to a patient is open-ended and requires ongoing treatment or hospitalization, which may make early resolution more difficult. Litigants and the courts will invariably look to other defective medical products for guidance. “The lawsuits that stem from defective catheter guidewires may follow the pattern established for the IVC filters that were designed to block blood clots,” explained Rachel V. Rose, a trial lawyer in Houston who is experienced in medical litigation. “In the case of guidewires, look for ‘bellwether’ cases in different parts of the nation to set the standard for monetary awards.”
 

Background

Coating a guidewire with PTFE is necessary for its smooth operation in the peripheral, coronary, and neuro vasculature. The coating reduces friction and eliminates the potential for binding and kinking during a procedure and, from the physician’s standpoint, the motion of the guidewire needs to be smooth and unhesitating. The difference in the tactile feel of a guidewire without and with PTFE is dramatic.

The origin of the problem of PTFE flaking on guidewires appears to correspond with the Environmental Protection Agency’s mandate earlier in this decade to eliminate the surfactant—PFOA—from water-borne PTFE formulations because PFOA is a suspected carcinogen. For 50 years, pure PTFE, with the aid of PFOA, had been the gold standard coating for guidewires. It is believed that PFOA improved adhesion to smooth metal surfaces, including guidewires. Without it, the flaking problem struck with a vengeance, especially when guidewires were soaked before use in the ever-present saline used in medical procedures. Saline penetrates the porous coating and, if adhesion is marginal, causes it to bubble and delaminate. Reports from operating theaters indicated that guidewires coated with the new PFOA-free PTFE were visibly flaking after being placed in saline soaking tanks.
 

An initial “fix” for the delamination problem was to switch from pure PTFE to resin-bonded PTFE. These early formulations are based on particles of pure PTFE and other low-friction particles, suspended in a tough polymer resin. While adhesion was improved, friction became a problem. While the coefficient of friction of pure PTFE is as low as 0.02 (similar to ice), the original resin-bonded coatings often had between 1.5 to 4 times more friction. Over time, the friction of the resin-bonded coatings has been improved, but not to the level of pure PTFE. This means the smooth operating feel of the old coated guidewires was lost, and the tactile feedback sensed by a physician operator is heavier, hesitant, and jerky. Known as “stick-slip,” this phenomenon is the transition from static friction to dynamic friction. Some physicians reported that they could not differentiate between a vascular obstruction and a momentary resistance of the guidewire.
 

There is another potential problem with resin-bonded PTFE: an unknown shelf life. If the substitute coating is not completely cured, it contains solvents that could adversely affect packaging, while the original water-based coatings had no such issue. Given all of this information, it appears that PTFE would be the ideal coating for guidewires as long as the delamination problem could be resolved once and for all.

Tags:teflon,ptfe teflon,gudiewire

The Impact of Fluoropolymers on the Medical Device Industry

The impressive growth of the medical device, biomedical and healthcare industries over the past 15 years continues unabated even as materials such as fluoropolymers are meeting the increasingly challenging demand for new products and procedures. In general, fluoropolymers are progressively replacing other plastics in medical applications owing to their ability to meet the physical and biocompatibility requirements of the next generation drugs and devices.  Fluoropolymers meet a unique set of performance criteria in such applications. These include biocompatibility, lubricity, sterilization, chemical inertness, a wide temperature use range, low binding to process equipment, high-purity with low extractables, dielectric properties, and USP Class VI certification.

The family of available fluoropolymers that meet the above needs include grades of PTFE, FEP, PFA and PVDF resin from various resin producers. PTFE(teflon) has a well-established implant history of soft tissue replacement due to its biocompatibility and inertness. Resin and downstream product manufacturers continue to respond to new performance requirements by making appropriate modifications to the chemistry of the resin and surface configuration of the products, respectively.

The biocompatibility of any polymer is a principal requirement in any medical device such as catheters, bio-containment vessels, syringes and sutures. PTFE, FEP and PVDF are well established biocompatible materials, and their lubricity and chemical resistance make them the material of choice for products such as multi lumen tubing and others that are used in minimally invasive procedures. Multi lumen fluoropolymer catheter tubing for example allows surgeons to perform multiple procedures using the same catheter.

Fluoropolymers, especially PTFE(teflon)and PVDF are widely used in microporous membranes. Membranes, containing billions of pores ranging in size from 0.01 to 10 microns act as filters for particles and bacteria in critical fluids. PTFE and PVDF are among the few polymers used for filter membranes. The surfaces of the polymers membranes can be modified to deliver specific filtration properties and can be hydrophobic (water repelling) and oleophobic (oil, solvent, low surface tension fluid repelling). PVDF membranes can be also be surface modified to be hydrophilic (water loving) for removal of viral particles in the manufacture of therapeutic proteins and monoclonal antibodies. PVDF blotting membranes are particularly well suited for low background immunoblotting (western blot analysis), as well as for amino acid analysis and protein sequencing.

Accessory equipment, such as pumps, tubing, fittings used in conjunction with medical devices must meet similar performance and specification parameters. Accessories in direct contact with fluids are constructed of fluoropolymers such as PTFE and PVDF. For example, metering pumps such as diaphragm pumps are required for precise and repeatable flow, sometimes for chemically aggressive fluids.  Both PTFE and PVDF tubing are used in the construction of these pumps for this reason.

PVDF, although having a lower use temperature limit than PTFE(teflon), has a relatively high tensile strength and excellent permeation resistance to many fluids. It has a lower density (1.78 g/cc) than other fluoropolymers (approximately 2.18 g/cc). Due to a lower melting temperature than other fluoropolymers, it is more easily processible into products such as pipes, tubes, injection molded parts and films. It offers excellent dimensional and UV stability and is therefore finding new uses in aerospace, sensors, biotechnology and robotics markets.

Tags:teflon, Fluoropolymers,medical device

Teflon – You might not realise, but it’s everywhere!

There are a few things about Teflon to start with that by no means tell the full picture, but are certainly the list of things that caused me to immediately abandon ship on all things teflon.

·         Teflon is the trademarked name for the chemical Polytetrafluoroethylene (PTFE).

·         Perfluorooctanoic acid (PFOA) used in the manufacture of Teflon products and banned by 2015, breaks down indefinitely in the environment. So think about everything in the list below that you’ve ever owned. Just one person. So scary to think about those particles never breaking down and ending up in oceans and rivers and US!

·         The off gasses from Teflon products kill birds. It’s really well known in vet circles. This usually comes from Teflon in certain light bulbs or cookware.

·         The women working in the Dupont factory where Teflon is produced had high incidence of birth defects and abnormalities, which DuPont was forced to pay millions in damages once exposed. The worst part? DuPont had known for 20 years that the PFOAs in Teflon technology was harmful to people, yet they remained silent.

·         It takes a pan about 3.5 minutes to reach 738F on an electric stove top with your average non stick pan. Teflon off gases 6 toxic gases from reaching about 680F, including carcinogens, global pollutants and a lethal chemical MFA.

·         At 1000F we get into warfare gases and a WWII nerve gas. Still hungry? Unbelievable isn’t it. It seems so often that big business simply does not have our best interests at heart. It ‘s soooo time to break up with them.

·         There are elevated levels of cancers, including some very rare, in and around the village where the DuPont factory is located.

·         The most common symptom in every day Teflon use, is with a high temperature cold and flu. Rarely are the two connected by doctors.

We largely know Teflon for its non stick qualities. So where else is it hiding? You’ll be surprised!

·      Frying pans, woks and saucepans – opt for stainless, cast iron or enamel when cooking. I use the De Buyer brand of brushed stainless, that you have to season similarly to a wok before using. SolidTeknics is awesome too and Australian made. Both are non stick, especially with a good bit of coconut oil, ghee or butter and I like to oil the pans after cooking and wiping clean to keep building a home-made non stick coating. Other options are ceramic coated, high quality brands like Le Chasseur or Le Creuset. Don’t baulk at the price – I’ve still got my grandmother’s roasting dish from 1972 and mum’s frying pans from the 70s too. It lasts literally forever!

·       Dental Floss. Something I discovered a few months ago.

·       Microwave popcorn bags – Best to pop in a saucepan.

·       Irons. The Sunbeam Aerosteam or the Tefal auto clean 400 are the only high quality ones that I’ve found, without the Teflon coating.

·      Hair straighteners, curling wands etc. Read the fine print on the packet and make sure it’s ceramic, stainless or don’t go near it!

·      Baking gear, including most parchment/grease proof paper! Opt for Stainless and do your good old fashioned butter and flour dusting to naturally ‘non stick’ your muffin, Madeleine or cake tins and opt for a parchment paper that is greener such as the fabulous If You Care soy wax for hot or silicon for cold coatings. Google ebay or etsy for stainless bakeware options and place an amazon order to your place you’re staying if traveling overseas so you can stock up on stainless bakeware without the postage fortune.

·      Carpets and sofas. Repeat after me: I will never tick ‘yes’ to free scotch guarding ever again! Any kind of sales pitch for stain repellent, liquid repellent technology, RUN A MILE and take your babies with you!

·       In a sports shoe shop. Step away from the scotch guard spray up-sell and take a pair of socks instead! If you have leather shoes, beeswax will be a fab water repellent and is all natural!

·      Waterproof mascara. Not in all of them, but Yes. It’s true. Check your brand. I buy this beautiful one. Just like my old favourite performance wise, minus all the extra weirdness!

·      Ironing board covers (not all. Check your brand / manufacturer)

·      Some light bulbs. Look for the words PTFEs or non stick to see whether your bulb is safe to buy or not. If you have pet birds or chickens, this is super crucial.

·     Toasted Sandwich makers, waffle makers, rice cookers and many plug in slow cookers and woks. Slow cook in large cast iron or enamel pans and put the lid on and dish into a low 130 oven. Easy. For rice? learn the absorption method. For toasted sandwiches?  Place your sandwich / wrap onto unbleached If We Care / other natural, parchment paper. Then, place another sheet on top and press as normal in the sandwich press. You can thank Mr Stuart for that genius tip, as he makes his way around a toxic free lunch in an office environment! Not easy…

·       Waterproof clothes, namely raincoats. Use umbrellas where possible.

·       Outdoor deck waterproofing sealants. There are natural ones available so it’s a matter of playing detective if you’ve got a renovation in the works.

·      In children’s uniforms! It will have a label and seems to be restricted to boy’s pants and shorts as far as I can see right now, which means you can find an equivalent colour, non teflon treated and avoid it. In large department stores or online, you can usually find cotton school-like colours. We’ve had success with it so far.

Tags:teflon ptfe,teflon

TEFLON, AN INVENTION THAT STICKS

1938: Fiddling around in the lab one day, Roy Plunkett accidentally discovers polytetrafluoroethylene, soon to be known as Teflon, a slippery substance that will have practical applications in everything from nonstick cookware to a presidential nickname.

Plunkett, a chemist at DuPont's Jackson research lab in New Jersey, made his discovery in the time-honored scientific way: as the result of a mistake, and with an assistant's help.

Plunkett and his assistant, Jack Rebok, were testing the chemical reactions of tetrafluoroethylene, a gas used in refrigeration. The gas was contained in some pressurized canisters, one of which failed to discharge properly when its valve was opened.

Rebok picked up the canister, only to find that it was heavier than an empty canister would be. He suggested cutting it open to see what had happened and, despite the risk of blowing the lab to kingdom come, Plunkett agreed.

Of course, it was heavy: The gas hadn't accidentally escaped. It had solidified into a smooth, slippery white powder as the result of its molecules bonding, a process known as polymerization.

This new polymer was different from similar solids like graphite: It was lubricated better and extremely heat-resistant, due to the presence of dense fluorine atoms that shielded the compound's string of carbon atoms.

Setting other work aside, Plunkett began testing the possibilities of polytetrafluoroethylene, eventually figuring out how to reproduce the polymerization process that had occurred accidentally the first time.

DuPont patented the polymer in 1941, registering it under the trade name Teflon in 1944. The first products — most having military and industrial applications — came to market after World War II. It wouldn't be until the early 1960s that Teflon became a household word when it was used to produce the most effective, heat-resistant cookware yet seen.

The word gained a certain pop-culture notoriety in the 1980s when the media began referring to Ronald Reagan as the Teflon president, a reference to his infuriating ability to avoid being tarnished by the various scandals plaguing his administration.

Teflon cookware, however, remained as steadfast and reliable as ever.

Teflon is found virtually everywhere today, coating metals and fabrics, from the aerospace industry to clothing to pharmaceuticals.

For his discovery, Plunkett, who retired from DuPont in 1975, was enshrined in the National Inventors Hall of Fame.

Source: About.com, Wikipedia

Teflon-coated cooking tools like this muffin tin and baking tray have eased setup and cleanup in millions of kitchens.

Tags:teflon,ptfe teflon,ptfe

8 Applications of PTFE Tubing

1. Aircraft Industries PTFE tubings are the non-flammable fluoropolymers that have lower friction coefficient which make them able to work properly under extreme temperature and pressure that's why these tubings are being used in the aircraft industries to wrap the wiring and cables.

2. Automotive Industries In the automobile engine, for fuel evaporation and fuel rails a high quality tubing is used which is made of Teflon PTFE which has low gas permeability.

3. Electrical Industries In electrical industries, to cover the electric wires and cables a high quality Teflon PTFE tubing is used that can bear the high temperature and protect the wire from any cuts. Also, these tubings are avalable in multi-colors that helps to identify the wires during the connection at homes or offices.

4. Medical Apparatus and Devices Fluoropolymers are used in medical industries to manufacture various instruments and devices like drainage tubings, ventilators, earpieces, aprones, gloves and other artificial tissues. Along with these, many functional devices which doctors use in biochemical analysis of human body are also made of the Teflon ptfe.

5. Food Industries In food industries for food processing special rollers are used. To expand the lifeline of these rollers wrap of Teflon FEP roll covers are done which are also non-sticky in nature that helps to maintain the quality of the product.

6. Textile Industries The transfer of chemicals in the pipes used in the textile industries cause corrosion. So, to avoid this problem Teflon TPFE tubings are used and also on the textile rollers the coating of PTFE done.

7. 3D Printing Industries In 3D printing, the filament should be transferred to the printing nozzle which have to perform under high temperature range. Since, the PTFE tubing has high temperature coefficient along with non-sticky nature which helps to easily slip the material from the nozzle so that it is most preferable polymer in the 3D printing industries.

8. Chemical Industries Non-alkali nature of the Teflon PTFE make it able to use in the chemical industries where transfer of the highly sensitive fluids is a common thing.

Tags:teflon ptfe,Teflon,ptfe tubing