by Denise Sullivan Denise Sullivan No Comments

Advanced Properties and Applications of PTFE in Sealing Technology

PTFE has a unique combination of properties that make it ideal for use in sealing technology. One of its most notable characteristics is its ability to withstand extremely high and low temperatures. PTFE can operate in temperatures ranging from as low as -200°C to as high as 260°C, making it an excellent choice for applications where sealing performance needs to be maintained at extreme temperatures.

PTFE

Another significant advantage of PTFE is its chemical resistance. It is highly resistant to various chemicals, including acids, alkalis, and organic solvents. This makes it an excellent choice for use in chemical processing plants or other facilities where exposure to harsh chemicals is common.

PTFE also has excellent non-stick properties, which make it ideal for use in applications where adhesion could compromise the effectiveness of the seal. Its low coefficient of friction means that even under heavy loads or with repeated cycles of movement, PTFE will not experience significant wear or degradation.

In addition to these properties, it has outstanding electrical insulation characteristics and acts as a barrier against moisture and dust.

Manufacturing PFE Gaskets

Pure PTFE gaskets are produced by molding directly from suspended material or cutting (turning) from PTFE sheets (rods). Molding plates have uneven density and poor flexibility while turning plates have a relatively uniform density. Still, their material is curved due to the influence of the processing technology, which is not conducive to installation and use.

Modified PTFE gaskets add a certain proportion of functional materials, such as glass fiber or graphite powder, during production. The resulting gasket provides improved strength and durability compared with pure PTFE gaskets while maintaining this advanced material’s desirable properties.

Despite its many advantages, however, some limitations are associated with using PTFE in sealing applications. For example:

  • It can be difficult to achieve consistent compression when using pure PTFE gaskets due to their poor flexibility
  • PTFE can be prone to creep under sustained pressure, which can result in a loss of sealing performance over time
  • PTFE is unsuitable for high-pressure applications as it has low tensile strength and may deform or fail under high loads.

Applications for PTFE 

Despite these limitations, PTFE remains one of the most advanced materials available in sealing technology. Its unique combination of properties makes it ideal for use in various applications where reliable sealing is essential.

One potential application area where PTFE could increase use is the automotive industry. As electric vehicles become more prevalent, there will be an increased demand for seals that withstand harsh operating conditions. Its excellent temperature resistance, chemical resistance, and non-stick properties make it an ideal choice for use in battery enclosures and other critical components.

Another potential application area is within the food processing industry. Many food products are highly acidic or alkaline, which can cause traditional seals to degrade over time. PTFE’s chemical resistance makes it an excellent choice for acidic or alkaline foods. At the same time, its non-stick properties mean that any residue left on the seal after cleaning can easily be removed.

In conclusion, Polytetrafluoroethylene (PTFE) has many advanced properties that make it ideal for use in sealing technology. Its ability to withstand extreme temperatures while maintaining effective sealing performance sets it apart from other materials commonly used in this field. While some limitations are associated with using the material in certain applications, such as those involving high-pressure loads, its unique combination of properties means it remains one of the most important materials currently available. Over time, we may see even greater advances made with this remarkable material with continued research and development into new formulations and manufacturing techniques.

by Denise Sullivan Denise Sullivan No Comments

The Effect Surface Finish Has on PTFE Seals

Surface finish plays an essential role in the effectiveness of PTFE seals. The different finishes provide different degrees of contact between the two components, which affects the seal’s strength and reliability. In this paper, we will discuss the effect of surface finish on PTFE seal performance and suggest ways to improve seal quality.

Surface finish on PTFE

The Influences of Surface Finish on Friction

The surface finish is critical for polymer-based seals. Despite being considered a soft plastic, PTFE is significantly harder than traditional o-ring materials. Because of this, if the mating surface is designed for other materials, it can cause the PTFE seals to leak.

As you can see in the graph below, the improvement in the surface finish has a favorable effect on the frictional force required.

The following specifications were used in the force test that resulted in the above data.

  • Stroke Speed: 4 in/min (102 mm/min)
  • Shaft Diameter: 0.1875in. (4.762mm)
  • Ambient Temperature: 73°F (23°C)
  • Mating Surface Material: 17 -4 PH S.S.
  • Mating Surface Hardness: -40 Rc

Surface Finish Influences on Wear

The finish of the mating surface is one of the main factors in the PTFE seal wear. Wear on the seal is generally proportional to frictional force. In other words, less friction reduces the wear on the seal. 

The following graph shows how a smoother surface finish reduces the PTFE seal wear rate.

To calculate the wear rate in microinches RMS, we used the formula IN3 -MIN/LB-FT-HR -10-9. For microinches Ra, we used the formula CM3 -MIN/KG-M-HR -10-9.

We used the following test parameters during our testing to ensure accuracy for each test.

  • Surface Speed: 55 fpm (17 m/min)
  • Loading Stress: 55 lb./in2 (4 bar)
  • Wear Rate in Air: @ PV 3025 lb./in2 x ft/min (7.5 N/mm x m/min)
  • Mating Surface Hardness: Rc 42
  • Matin Surface Maerial 17 -4 PH Stainless steal
  • Mating Surface Finish: 1.6 to 111.1 microinches RMS (1.4 to 100 microinches RA)
  • Ambient Temperature: 70°F (21°C)
  • Ambient Relative Humidity 75% RH
  • Duration 5 Hours
  • Seal material FP

Influences on Sealing Ability

Finally, we looked at how the surface finish affected PTFE’s sealing ability. In general, the sealing ability of PTFE is proportional to the fluid’s viscosity. If a media, like gas, has a reduced viscosity, it is more difficult to seal. In these situations, having a smoother finish on the mating surface can help ensure fewer leaks.

We’ve found that different mediums require not only different finish ranges between them but also different finish ranges when considering if the surface is dynamic or static. You can see our suggested finish in the table below.

MediaDynamic Surface Static Surface 
Gases and Liquids at Cryogenic Temperatures2 to 4 microinches RMS
(1.8 to 3.6 Microinches Ra)		4 to 8 Microinches RMS
(3.6 to 7.2 Microinches Ra)
Gas at Non-Cryogenic Temperatures6 to 12 Microinches RMS
(5.4 to 10.8 Microinches Ra)		12 to 32 Microinches RMS
(10.8 to 28.8 Microinches Ra)
Liquids8 to 16 Microinches RMS
(7.2 to 14.4 Microinches Ra)		16 to 32 Microinches RMS
(14.4 to 28.8 Microinches Ra)

As you can see, the mating surface finishes can profoundly affect PTFE seals. Because of this, if the mating surface is designed for other materials, it can cause the PTFE seals to leak. Finally, we examined how this affected PTFE’s sealing ability. In general, the sealing ability of PTFE is proportional to the fluid’s viscosity. 

by Denise Sullivan Denise Sullivan No Comments

HPLC Spring Energized Seals

HPLC spring energized seals

High-performance liquid chromatography is the ideal method for analyzing various solutions in different fields. This machine, however, requires HPLC spring energized seals that adhere to strict guidelines with slight variation.

Different Liquid Chromatography Types

There are a few different types of liquid chromatography. The primary liquid chromatography types include high-performance liquid chromatography (HPLC), preparative HPLC, and ultra-high-performance liquid chromatography.

High-performance liquid chromatography is used in multiple different industries. HPLC is found in food science, drug development, and forensic analysis. It is used to separate compounds and used for quantitative and qualitative analysis.

Preparative HPLC is used in purification applications as it requires a higher flow rate. This liquid chromatography is also used to separate and collect high-purity compounds. It is also used for large quantities of compounds needed for evaluation and analysis.

Ultra-high-performance liquid chromatography (UHPLC) is similar to HPLC. It is used to separate different constituents of a compound and to identify and quantify the different components of a mixture. 

Operating Conditions

HPLC pumps operate in conditions with variable flow rates and small shaft diameters. They have tight leak criteria and operate under a wide range of pressures. HPLC pumps have a medium-speed reciprocation.

Seals in HPLC pumps must withstand the solvents used to separate compounds dissolved in the liquid sample. Solvents used in HPLC include 

  • MeOH (Methanol)
  • ACN (Acetonitrile)
  • H2O (Water).

The expected lifetime for seals in HPLC pump environments is a minimum of one million cycles. Seals may last longer depending on the flow rate, pressure, and media.

Seal Designs

HPLC seals prevent leaks from occurring. Should the mile phase lack into the back of the pump, it will impact consistency, accuracy, and pump precision. To effectively prevent leaks, seals should have effective leak resistance in pressures up to 20 kpsi.

Seal Geometry

The geometry of the seal is an important factor. For HPLC pumps, a flange design helps reduce the pump’s pulsation. HPLC spring energized seals have a longer seal ID lip and a polymer backup ring to increase the amount of contact stress.

UHPLC seals have a non-flange design and a shorter seal ID lip. Instead of a polymer backup ring, it uses a ceramic or metal backup ring. These seals have a concave back for higher-pressure distribution.

Jacket Materials

HPLC pumps’ seals have a PTFE or UHMW PE jacket. The UHMW PE material is used in systems with pressures greater than ten kpsi. UHMW PE is an FDA-compatible material for both food and pharmaceutical analysis.

PTFE jackets are the most chemical resistant of the common materials. The PTFE jackets are filled with graphite or polyimide. These fillers are heat and wear-resistant and work well in liquids and steam.

Performance Factors

Sealing performance factors are affected by the different surfaces in the HPLC pump. The housing surface has a suggested static sealing surface between 9.1 to 14.5 μin Ra.

On the plunger surface, a smoother surface is best. For virgin PTFE or UHMW PE, a minimum shaft hardness is 40Rc. The suggested dynamic surface is 7.3 – 14.5 Ra μin.

 

Medium Dynamic Surface Static Surface
Reciprocating Rotary
RMS  Ra μin  RMS Ra μin  RMS Ra μin 
Liquids 8 to 16 7.2 to 14.4 8 to 12 7.2 to 10.8 16 to 32

14.4 to 28.8

Plunger alignment needs to have a minimal shaft-to-bore misalignment with tight concentric guidance between the wash body and pump head. For best sealing performance, the shaft-to-bore misalignment should be kept to a minimum. 

Shaft To Bore Misalignment at the Seal Area
Shaft Diameter (in inches) Shaft to Bore Misalignment (in inches)
0.000 – 0.750 0.0020
0.751 – 1.500 0.0025
1.501 – 3.000 0.0030
3.001 – 6.000 0.0035
6.001 – 10.000 0.0045

 

HPLC Spring Energized Seal Recommendations

The HPLC spring energized seal requirements should be considered during the pump design process. Designers should collaborate with seal engineers early in development. Contact us today to get a quote on your next custom seal needs. 

 

by Denise Sullivan Denise Sullivan No Comments

High Performance Electric Vehicle Seals

electric vehicle seals

 

There is a push for more people to drive electric vehicles. While they are more environmentally friendly, the motors differ significantly from traditional combustion engines. Electric vehicle seals must keep lubrication confined to the gearbox, dirt, and debris out of the motor while providing engine efficiency.

In this article, you will gain a basic understanding of

  • How electric vehicles and internal combustion engines differ
  • Design considerations for electric vehicle seals
  • Types of materials used in making seals for electric vehicles

Differences in Electric Vehicle and Internal Combustion Engines

If you are standing outside an electric vehicle looking at it, you may not notice many differences between it and a gas-powered automobile. The overall external design is the same, except the electric car has no exhaust pipe.

However, below the surface, the two engines are significantly different. Gas-powered have a gas tank, gas pump, motor, carburetor, alternator, smog controls, and hundreds of other moving parts. In addition, the engine requires seals to keep oil and other fluids from leaking out. 

An electric vehicle engine only has one main moving part: the motor. Despite the motor being in a dry environment, seals are still required to help keep dirt and dust out of the engine and the lubricants needed for the vehicle gearbox. 

Both electric vehicles and internal combustion engines require specialized seals to keep the motors/engines working efficiently.

Electric Vehicle Seal Design Considerations

Electric vehicle motors work more efficiently and require seals that can handle their unique needs. The seals used in electric vehicles often exceed the minimum requirements of seals found in internal combustion engines. In addition, many of them must work in dry environments.

Friction

Friction is one of the primary design considerations for electrical vehicle seals. While friction in any engine is not desired, electric vehicles need a lower friction seal than traditional gas-powered engines. Any friction created by seals causes efficiency loss in power output. 

If the engine isn’t efficient, the battery won’t be able to have the range that it should. A motor working harder to make up for the efficiency loss won’t be able to travel as far as it should. Lower friction is essential to gain better efficiency and long distance. 

Dry Running

Electric vehicles require both dynamic and static seals. The dynamic seals are often called rotary lip seals.  While they don’t require oil seals, electric motors need seals that work in a dry-running environment. 

The primary shaft uses a rotary seal to prevent dirt, dust, and water from entering the electric motor. If fluid and debris enter the motor, it can damage the engine and cause it to break down or damage some of the highly charged electrical components so that it won’t work efficiently.

In addition to running in a dry environment, the rotary seals must withstand the higher speeds electric motors run. The components spin up to 18,000 rpm, about three times faster than a traditional combustion engine. As a result, seals in these engines have to withstand high-speed running without lubrication.

Electric Vehicle Seal Materials

Not all materials common seal materials work well in electric vehicles. However, two of the more common types are PTFE and molded rubber. The materials are used for different applications but are necessary as part of the vehicle’s makeup.

PTFE Seals

Polytetrafluoroethylene (PTFE), more commonly known as Teflon, is a nonreactive material with a low coefficient of friction. Therefore, it is ideal for high-temperature environments found in an electric vehicle motor.

Seals made from PTFE are usually found on the e-axle and help to act as a barrier between the motor and gearbox. The engine is a dry environment, while the gearbox requires lubrication. The PTFE seal keeps lubricant from seeping into the motor. In addition, the seal’s dry side has a lip that keeps dust and dirt out of the engine.

In addition to keeping the lubricant in the gearbox and dirt out of the motor, the PTFE rotary seal can withstand the high speeds in the car’s engine. Additionally, it provides low friction to keep the motor running efficiently.

Molded Rubber

While PTFE is the ideal seal material for the e-axle, molded plastic is the perfect solution for valve housing. The valve housing needs a seal that will withstand high temperatures and pressure in the area. The T-junction area of the seal is the most problematic area known for failure. 

Molded rubber seals are push-in-place rubber gaskets that perform well under pulsating pressure. These gaskets can handle temperatures of up to 302°F (150°C) and 50 Bar pressure. In addition, it requires more gland space than seals used in a traditional combustion engine.

Conclusion

Electric vehicles are rising in popularity. However, due to the nature of their engines, they require different seals than a traditional combustion engine. These seals need to have lower friction and handle high-speed rotation.

Need seals for your electric vehicle manufacturing? Contact us today to find out how we can create custom seals for your project.

Auto Molding PTFE Seals and Seats
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Auto Molding PTFE Seals and Seats: Advantages for High-Volume Production Runs

Auto molding PTFE seals and seats offer a wide variety of benefits, especially for high-volume production runs. In this blog post, we cover some background on both PTFE and auto molding (also known as compression molding) and discuss why this particular manufacturing process is often preferred by engineers for both seals and ball valve seats.

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Tail view of a commercial aircraft
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

PTFE Aerospace Seals

Finding the right sealing solution for aerospace applications involves a host of considerations, especially when it comes to the jacket material. However, there is one high-performance solution that rises to the top over and over: PTFE aerospace seals. 

Aerospace Seal Challenges

Aerospace sealing solutions can face a wide range of harsh environments that can include exposure to extreme temperatures, high pressures, and corrosive chemicals such as de-icing liquids and aviation fuels. There is also the ever-present demand for energy-efficient solutions,  critical requirements related to safety, and compliance with industry standards. 

In addition, aerospace seals must often perform in potentially explosive or flammable environments. There are other constraints in aerospace applications as well, such as the need to minimize weight and promote energy efficiency. And looking to the future, there will also be demand for more environmentally friendly, sustainable solutions.

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Teflon PTFE Seals for Static and Dynamic Sealing

Advanced EMC Technologies’ Teflon PTFE seals are one of their frontline products, in continuous demand across many industries. The seal offers perfect static and dynamic sealing for the most demanding applications. Other key features include low friction, chemically resistant, dry/lubricated running used in many industries such as fluid handling, semiconductor, aerospace and instrumentation..

Talking about it, a senior executive with the company said, “The component is an integral part of the equipment across industry sectors. It can withstand extreme temperature, chemicals and pressure. Sealing jacket is made of resilient PTFE and can be energized by an internal spring when needed which applies a load to the sealing element at low pressures. It has unlimited shelf life and controlled friction/load.”

Spring energized seals have a resilient seal jacket and compensates for jacket wear, hardware misalignment or eccentricity. Polymer seal jackets materials include Virgin PTFE, Carbon/Graphite PTFE, Moly/Filled PTFE, Glass/Moly PTFE, Polyimide/Filled PTFE, UH/Polymer PE, 60% Bronze / filled PTFE and PCTFE / KEL F. FDA approved low friction Virgin PTFE is excellent for light duty service, cryogenic applications and low molecular weight gas service.

Carbon/Graphite PTFE offers superb resistance to heat and wear. Good in liquids and steam, it is recommended for dry or semi-dry applications. The executive added for Glass/Moly PTFE, “It works well for high pressure applications and is impressive in hydraulic, steam and water. The material is abrasive in rotary service against soft metals.”


Teflon Spring Energized PTFE Seals by Advanced EMC by PTFEseals

Polyimide/Filled PTFE seals are outstanding in dry service with low wear rate in vacuum and inert gases. It has very low abrasion to dynamic mating surfaces. UH/Polymer PE has higher friction than PTFE compounds. Static and slow dynamic PCTFE / KEL F is best grade for cryogenic applications. 60% Bronze / filled PTFE excels at very high rotary speeds with low pressure.

About Advanced EMC Technologies

Advanced EMC Technologies is an acclaimed company offering industrial grade polymer seals and bearings. The company deals in PEEK polymer seals, spring energized Teflon seals, PTFE rotary shaft seals, polymer bearings and bushings, precision components, nylon bushings and several other such products. The company provides quality products to meet budget and service expectations to clients.

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Advanced EMC – Offering High PV Grades, FDA Compliant PTFE Seals

Businesses in Texas needing chemically resistant, low friction static and dynamic sealing solutions can procure these from Advanced EMC Technologies. They produce high grade FDA compliant PTFE seals that can withstand extreme temperature and pressure.

An executive with the company threw more light on the feature saying, “As the system pressure raises enough to take over from the spring and engage the shaft an ultra-efficient seal is created. The spring of the spring energized seal provides permanent resilience to the seal jacket compensating for jacket eccentricity, wear and hardware misalignment.”

Other salient features of the seals are fluid handling, high PV grades, unlimited shelf life, controlled friction/load and FDA/USDA compliance. The seals are efficient in dry running or lubricated, cryogenic and HPLC applications. They can effectively be used across sectors like medical and defense, medical, biomedical, food service, oil & seismic transportation and pharmaceutical. Polymer seal jacket are made of varied materials like virgin PTFE, carbon/graphite PTFE, moly/filled PTFE, glass/moly PTFE, polyimide/filled, UH/polymer PE, 60% bronze/filled PTFE and PCTFE/ KEL F.

FDA approved Virgin PTFE are known for low friction and light duty service. The executive elaborated, “1000 Fluorolon Virgin PTFE seals are excellent for cryogenic and low molecular weight gas service. It can withstand temperature range of -320 to 450F. Extrusion resistance and friction rating is lowest. Carbon/Graphite PTFE 1034 Fluorolon jacket seats, on the other hand offer excellent resistance to heat and wear. It is recommended for dry or semi-dry apps. It can stand temperature ranges of -320 to 500F. Extrusion resistance is moderate and friction rating is low.”

1017 Fluorolon Moly/Filled PTFE seals are excellent in dry gas with better wear resistance. Temperature range is -320 to 525. Extrusion resistance is very high and Friction rating is low. 1050 Fluorolon Glass/Moly PTFE seals offer superlative wear and heat resistance. These are abrasive in rotary service against soft metals and effective in high pressure applications. It is meant for temperature ranges of -250 to 550F, have very high extrusion resistance and moderate friction rating.