by Brandon Pascual Brandon Pascual No Comments

Maximizing the Performance of Your PTFE Rotary Shaft Seals

Maximizing the Performance of Your PTFE Rotary Shaft Seals

PTFE (Polytetrafluoroethylene) rotary shaft seals are known for their durability and efficiency in extreme conditions. Whether you’re working in automotive, aerospace, or industrial sectors, understanding how to maximize the performance of these seals can save time, reduce costs, and improve operational efficiency. This practical guide covers the essential factors that influence the performance of PTFE rotary shaft seals and the environments in which they excel.

WHY PTFE ROTARY SHAFT SEALS ARE ESSENTIAL FOR HIGH-PERFORMANCE MACHINERY

1. Understanding Mating Surface Requirements

The surface over which the PTFE seal operates is crucial for its longevity and efficiency.

  • Surface Finish: Ensure the surface finish is within the recommended range (2 to 16 RMS). Too rough, and the seal wears out quickly; too smooth, and it can’t form the necessary PTFE film. For cryogenic applications, aim for a finish of 2 to 4 RMS​​​​.
  • Surface Hardness: A harder surface reduces friction and wear. For low to moderate motion, a hardness of 40 RC is sufficient. For high-speed rotary motion, opt for 55 RC to 65 RC​​​​.

SEALS IN SPACE: THE UNSUNG HEROES OF ROCKETRY
🔬 THE FASCINATING JOURNEY OF POLYTETRAFLUOROETHYLENE (PTFE) 🧪

2. Choosing the Right Material and Surface Treatment

Selecting appropriate materials and treatments enhances the performance of PTFE seals.

  • Materials: Stainless steel (440C or 17-4) is commonly used. These materials achieve the necessary hardness through heat treatment.
  • Surface Treatments: Treatments like electroless nickel plating or gas nitriding improve surface hardness, crucial for seal effectiveness. For example, gas nitriding can achieve up to 70 RC hardness​​​​.

🚀ADVANCED SEALS FOR CRYOGENIC HYPERGOLIC BIPROPELLANTS

3. Selecting the Right Seal for Your Application

Advanced EMC Technologies offers various PTFE seal designs to meet different operational needs:

  • Series A Seal: Ideal for moderate conditions, handling pressures up to 75 psi​​.
  • Series B Seal: Suited for higher pressure applications, up to 125 psi, providing additional protection against contaminants​​.
  • Series C Seal: Spring-loaded for better sealing under shaft misalignment, perfect for submersible pumps​​.
  • Series D Seal: Best for conditions with shaft runout or misalignment, maintaining effectiveness during long-term storage​​.
  • Series E Seal: Capable of withstanding pressures up to 400 psi in lubricating media, designed for high-speed operations​​.

A COMPREHENSIVE GUIDE TO AEROSPACE SEALS

4. Adapting to Operating Conditions

PTFE seals are versatile, handling various temperatures and pressures:

  • Temperature Range: Operate effectively from cryogenic conditions (-450°F) to high temperatures (500°F)​​.
  • Pressure: Suitable for high-pressure environments up to 500 psi, ideal for hydraulic systems​​.

THE REVOLUTIONARY IMPACT OF PTFE ROTARY SHAFT SEALS ON INDUSTRIAL APPLICATIONS

5. Ensuring Media Compatibility

PTFE’s chemical inertness ensures it can seal a variety of aggressive media, making it suitable for applications involving steam, corrosive chemicals, and other harsh media​​. Here are some examples of environments where PTFE rotary shaft seals excel:

  • Steam Environments: PTFE seals are commonly used in steam turbines and autoclaves. For example, in power generation plants, PTFE seals ensure reliable performance by resisting high-temperature steam and preventing leaks.
  • Chemical Processing Plants: In environments where corrosive chemicals like sulfuric acid, hydrochloric acid, and sodium hydroxide are used, PTFE seals provide excellent resistance. For instance, in chemical reactors and storage tanks, these seals prevent leaks and maintain the integrity of the system.
  • Pharmaceutical and Food Industries: PTFE’s compatibility with various solvents makes it ideal for mixers and pumps. In pharmaceutical manufacturing, PTFE seals prevent contamination during the processing of active ingredients and solvents. Similarly, in the food industry, they ensure sanitary conditions by resisting cleaning agents and maintaining seal integrity.
  • Aerospace Applications: PTFE seals are utilized in aircraft engines and space vehicles due to their ability to withstand extreme temperatures and pressures. For example, in rocket engines, PTFE seals maintain performance under the harsh conditions of space travel, including exposure to cryogenic fuels and high-speed rotation.
  • Oil and Gas Industry: PTFE seals are used in drilling equipment and pipelines, where they encounter high pressures and aggressive media like crude oil and natural gas. These seals ensure reliable operation and prevent leaks in high-stakes environments.

ADVANCED PROPERTIES AND APPLICATIONS OF PTFE IN SEALING TECHNOLOGY

6. Utilizing Fluoropolymer Material Enhancements

Enhance PTFE performance by selecting the right filler material:

  • Unfilled PTFE: Low friction, ideal for food and pharmaceutical applications, and cryogenic conditions​​.
  • Glass-Filled PTFE: Adds strength but can be abrasive. Best for harder surfaces​​.
  • Molybdenum Disulfide-Filled PTFE: Improves wear resistance without being too abrasive, suitable for softer shafts​​.
  • Carbon-Filled PTFE: Excellent for high-temperature, high-pressure environments, providing natural lubrication​​.
  • Polyimide-Filled PTFE: Enhances creep resistance, ideal for compressor rings and similar applications​​.

EXPANDED PTFE VS. PTFE

INTRODUCTION TO PTFE LIP SEALS

Maximizing the performance of PTFE rotary shaft seals involves understanding and optimizing several factors, including the mating surface characteristics, material selection, and operating conditions. By selecting the appropriate seal design and ensuring media compatibility, you can significantly enhance the reliability and lifespan of your seals in various demanding environments.

For more information on PTFE rotary shaft seals and to explore Advanced EMC Technologies’ offerings, visit Advanced EMC Technologies.

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.