When to Use PEEK, PTFE or Nylon Backup Rings

Backup rings, also known as anti-extrusion rings of BURs, do exactly what their name implies: they act as back up support to sealing assemblies.

There are several different materials used to make backup rings, including both polymers and elastomers. The most common polymers for backup rings are PEEK, Nylon, and PTFE. Deciding which material to use is typically based on pressure and temperature requirements.

In this blog post, we will review the purpose and applications of backup rings, then discuss the ranges of pressure and temperature that PEEK, Nylon, and PTFE are suited for.

Purpose of Backup Rings

A properly designed backup ring placed between the o-ring and the clearance gap can prevent the o-ring seal from extruding into the gap while providing both support and protection to the o-ring. They work well in situations where there is a large extrusion gap, high temperatures, or high pressures.

Backup rings are are commonly used in:

• valves for hydraulic circuits
• chemical pumps
• injection molding machines
• adhesive dispensing valves
• presses
• machine tools
• pharmaceuticals
• agricultural machines  

PEEK Backup Rings

PEEK can be used at pressures up to 20,000 psi and and a maximum temperature of 500°F.  This makes PEEK ideal for high pressure and high temperature applications. PEEK is also available filled for addition strength and hardness. PEEK is quite compatible with a variety of chemicals, including cleaning compounds, and has low friction.  

Nylon Backup Rings

Nylon 6,6 works well at pressures below 10,000 psi and a maximum temperature of 186°F. Nylon works well for high pressure applications but is quite limited with regard to temperature. Nylon 6,6 filled with Molybdenum Disulfide (MoS2) to reduce friction is commonly used for backup rings. One of the drawbacks of Nylon 6,6 is its water absorption, which can range from 0.5% to 1.4% per 24 hours.

PTFE Backup Rings

Filled PTFE (glass filled, carbon filled, graphite filled, bronze filled) works with pressures up to 5,800 psi, however virgin PTFE is limited to about 3,600 psi. Virgin PTFE, therefore, is limited to low and medium pressure applications while filled PTFE works for many medium to high pressure applications. The maximum operating temperature for PTFE is around 575°F, which makes it ideal for low pressure, high temperature applications. PTFE is very chemically resistant and has extremely low friction.

Conclusion

When it comes to backup rings, PTFE works well for low to medium pressure applications but can also handle high temperatures. Nylon can handle medium to high pressure applications but is limited by operating temperature and water absorption. When it comes to backup ring materials, PEEK is can handle the highest pressures and fairly high temperatures. Keep in mind that PEEK and PTFE are comparable when it comes to low friction and chemical compatibility, both of which are important in sealing applications
Tags:teflon ptfe,peek,nylon,back up rings

PTFE and UHMW Choice for Non-stick Bearings and Bushings in Food & Dairy Industry

Food & Dairy Bearings and Bushings:

Bearings and bushings can be found in almost every step in food or dairy processing industries.  Polymers are a popular choice for bearings and bushings in the food and dairy industry, both at the design stage and when retrofitting.  Because they are greaseless, the can provide a more sanitary environment for food processing.  They don’t require the maintenance that metal bearings and bushings require, thus reducing downtime for maintenance.  Their durability results in longer mean times to failure.  They are usually much more resistant to corrosion and much less chemically reactive than metal bearings and bushings.  They also weight much less than equivalent metal bearings and bushings.

Non-stick Applications

These are all good reasons to use polymer bearings in the food and dairy industries, but what about situations where one of the design requirements is non-stick bearings?  That is not a problem at all. There are, in fact, two specific plastics that are commonly used in these situations:  PTFE and UHMW PE.

PTFE

PTFE, or Teflon, is well known for its anti-stick properties due to its use as a coating for cooking utensils.  In fact, even Geckos can’t hang on to PTFE.  PTFE is also hydrophobic.  It is usually known among engineers for having the lowest coefficient of friction any polymer or metal in existence.  It is also the least chemically reactive polymer, and has excellent wear properties.  It absorbs a minimal amount of moisture.  PTFE, in its virgin form, is odorless and tasteless.  It has FDA approval.

UMHW PE

UMHW (ultra-high molecular weight) PE (polyethylene) is known for its toughness, including the highest impact strength of any polymer currently available.  It has no moisture absorption. Its coefficient is low enough to be comparable to PTFE. More importantly, like Teflon, it provides a non-stick surface. It is often chosen because of its ability to resist material hang-up. Among its other properties is an abrasion resistance that is 10x that of carbon steel.  UMHW PE is tasteless, odorless, and nontoxic.  It has been approved by the FDA, USDA, Canada AG and 3A dairy.

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Conclusion

If you are designing equipment for the food and dairy industry, or looking to retrofit existing equipment, and require non-stick bearings or bushings, look no further than PTFE and UHMW PE.

Tags:teflon ptfe,UHMW,food industry

5 Applications for PEEK in the Medical Device Industry

There are millions of medical devices that include components made from PEEK.  This usage has grown tremendously in the past fifteen years and is still evolving. In this post, we are going to look at typical applications for PEEK in the medical device industry, including both implantable devices and non-implantable devices.

#1 PEEK in Spinal Applications

A stiffness comparable to that of human bone, radiolucent properties, and reduced stress shielding are just a few of the features that make PEEK an excellent choice for spinal applications.

Spinal applications of PEEK include:

• minimally invasive spinal implants
• disc arthroplasty,
• anterior cervical plates,
• dynamic stabilization and motion preservation
• interspinous spaces
• posterior spine stabilization rods

#2 PEEK in Orthopedic Applications

Arthroplasty and arthroscopy have made extensive use of PEEK for several years, including knee and shoulder arthroscopy along with knee and hip arthroplasty. The implementation of PEEK in hip cups has been especially useful. PEEK works very well for knotless suture anchors in shoulder arthroscopy. Tibial screw anchors and sheaths made of PEEK provide excellent strength and far less failure.

Benefits of PEEK for orthopedic applications include:

• improved stability
• significantly better wear performance
• and less need for revision

#3 PEEK in Trauma Applications

PEEK is also used in bone trauma applications such as fracture fixation plates and intramedullary (fracture fixation) nails.

The usage of PEEK in trauma applications results in outcomes such as:

• improved healing rates
• better pain relief
• more straightforward MRI and CT imaging when compared to their metal counterparts

#4 PEEK in Dental Applications

PEEK is also used in precision, customized dentures and prosthetics that are an alternative to traditional metal dentures. They have been found to be far more comfortable, easier to tailor to a patient’s needs and an excellent fit for the modern CAM/CAD approach to dental prosthetics.

#5 PEEK in Non-Implantable Devices

Not all PEEK applications in the medical industry are for implantable devices. PEEK can be found in pumps, pistons, fluid transfer applications, and valves. PEEK seals and bearings are well established for use in critical medical and pharmaceutical applications such as dialysis, equipment, blood pumps, infusion pumps, reusable medical instruments, medical device fixtures, or tissue cutting tools.  

Why PEEK

In applications such as this, PEEK medical devices offer superior fatigue properties and low moisture absorption, which is critical in implantable devices. PEEK components are also more compatible with diagnostic imaging with no artifacts. Some grades of PEEK are radiolucent. Through fiber reinforcement, mechanical properties such as stiffness can be customized to meet application needs.It is possible to achieve a stiffness that approximates human bone using PEEK. Biocompatibility and biostability of load-bearing medical implants is another critical area in which PEEK excels. PEEK can also be manufactured using many different methods.

Conclusion

PEEK is used in many different areas of the medical industry, from implantable devices that have to be both strong and biocompatible to reusable medical instruments that have to be sterilized repeatedly using harsh processes such as autoclaving. PEEK is an good choice for medical applications for numerous reasons, including its excellent fatigue/wear properties, high strength-to-weight ratio, and biocompatibility.

Tags:peek,applications, polyetheretherketone

PTFE ELECTRICAL TAPE

The base material was made via fiberglass impregnation in PTFE and refined, coating with silicone adhesive and with excellent heat resistant and mechanical strength.
Good release and smooth
Good performance of high temperature keeping, stable size.
Small friction coefficient, good insulation.
Good corrosion resistance.

Applications
1. According to different thickness, can be using as many kinds of drying machine conveyor, bonding tape, sealing tape.
2. Using for welding cloth for plastic products welding, backing mat for plastic, film, hot sealing
3. Electrical insulation, mat, gasket, and so one.
4. Heat cladding layer, pack of heat insulation body.
5. Microwave mat,, oven chips, food drying.
6. Adhesive tape, hot transfer printing table cloths, and so on.
7. Backing cloth for pressure sensitive ahdesive.
8. Architectural membrance, many place of canopy, etc.
9. For various petrochemical pipeline corrosion resistant cladding, power plant emissions, environmental desulfurization.
10. A flexible compensator, the friction material, wheel slice.
11. After special processing, making "anti-static cloth.

Material: PTFEE ; Color: Brown ; Surface friction coefficient: 0.05~0.1 ; Insulating coefficient: >=1012 ohm ; Adhesion strength (to metal):  28N/100mm ; Tensile strength: 1700N/100mm ; Temperature resistance: -70-300°

Tags: PTFE Electrical Tape,PTFE Tape

Beginner’s Guide to PTFE and PEEK Backup Rings

Backup rings can be made from a variety of materials, including polymers. In this article, we will look at PTFE and PEEK backup ringswhile at the same time reviewing some of the basics of backup rings.

Why Use Backup Rings?

Rubber o-rings are good, but when temperatures and pressures rise they have a bad habit of extruding into clearance between mating surfaces, which isn’t a good thing. In fact, extrusion failure is one of the main causes of o-ring failure. As the o-ring begins to extrude into the clearance gap, it will experience more and more damage until it is useless. This phenomenon is sometimes called nibbling, and when it occurs you will notice that the o-ring will have a ragged edge on the low-pressure side.

Backup rings, also known as anti-extrusion rings, are used to keep o-rings from extruding into areas where they don’t belong. They are also used in conjunction with seals to either prevent damage to the seal or to control extrusion. Backup rings are made of an extrusion resistant, hard material. They fit between the o-ring (or seal) and the extrusion gap.

Where Should Backup Rings Be Used?

Backup rings are suggested for o-ring failures such as extrusion/nibbling (as we already discussed) and spiral failure (where cuts or splits spiral around the circumference of the o-ring). They should be used when temperatures or pressures are expected to reach a level that would cause the seal or o-ring to extrude. This could be continuous operating conditions or, as is quite common, pressure or
temperature spikes. Backup rings are also used when the design requires a large extrusion gap.

Note that when used with seals, backup rings are usually placed downstream of the seal gland.

Finally, backup rings can be used in both static and dynamic applications.

What Kinds of Materials Are Used for Backup Rings?

Two of the most common materials used for backup rings are PTFE and PEEK. Both PTFE and PEEK are far less likely to extrude than the elastomers used for seals and o-rings. This means they can retain their shape even in the presence of elevated temperatures, high pressures, and aggressive chemicals. This allows them to hold the o-ring or seal in place.

Both PEEK backup rings and PTFE backup rings are usually filled, meaning they have a filler material such as glass or carbon fiber added to increase their compressive strength and dimensional stability.  Another benefit of using PEEK and PTFE for backup rings lies in their chemical resistivity, making them ideal for chemically aggressive environments. They also have low friction and relatively high continuous operating temperatures.

Conclusion

PTFE and PEEK are popular choices for backup rings because they are dimensionally stable, chemically resistant, have excellent compressive strength, and function well even at elevated temperatures and pressures. As an anti-extrusion device, they work extremely well with both o-rings and seals to prevent extrusion in situations that involve large clearances, high temperatures, and high pressures. If you are experiencing extrusion issues, don’t forget to consider a backup ring!

Tags:teflon ptfe,ptfe,peek,rings

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.
Tags：ptfe,teflon ptfe,seals

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