Torlon PAI Molecule
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Torlon Bearings: Properties, Performance, and Engineering Applications

Torlon bearings are high-performance solutions designed for extreme performance even under extreme loads, high temperatures, and aggressive wear conditions. In this blog post, learn why more and more engineers are opting for Torlon bearings based on Torlon’s properties, bearing performance characteristics, and diverse areas of applications.

Properties of Torlon Bearings

Chemical Structure and Material Classification

Torlon® (polyamide-imide, PAI) is a high-performance engineering polymer. It is a hybrid polymer that combines the characteristics of both polyamides and polyimides, offering excellent toughness, thermal resistance, and mechanical strength. Its aromatic monomers, which reduce molecular mobility, give it stiffness, creep resistance, and high-temperature capabilities. 

The imide linkages in Torlon give it a high bond strength, allowing it to resist chain scission at extremely high temperatures. In addition, the imide groups provide excellent resistance to oxidative degradation, extending their service life in oxygen-exposed environments.

This combination of aromatic monomers with imide linkages enables it to have a high continuous-use temperature of up to 500°F without losing its key mechanical properties. Torlon’s combined imide and aromatic bonding networks also enhance its wear resistance, which is critical in poor-lubrication or dry-running operating conditions.

Torlon’s molecular architecture enables bearings to provide reliable performance even under high PV loads and improves their compressive strength to support high-load-bearing applications. In addition, its chemical makeup enables Torlon to outperform many other engineering polymers in applications that demand dimensional stability under heavy mechanical cycling or extreme thermal spikes.

Thermal Properties

Torlon is known for its continuous-use temperatures approaching 260°C (500°F), as well as its excellent retention of mechanical strength at such elevated temperatures. Torlon also exhibits very low thermal expansion. Its primary thermal drawback lies in manufacturing: it is primarily limited to compression molding and machining because of its high melt processing temperature. 

Mechanical Properties

Torlon is known for its excellent strength and stiffness, including a high load capacity. Two of the bearing grades of Torlon are …

  • Torlon 4435: high-temperature, low-friction, high-PV
  • Torlon 4301: high strength, low friction, graphite-filled

Tribological Properties

Naturally low friction coefficients are another key property of Torlon. These values can be improved by using PTFE- or graphite-filled material. Moreover, Torlon has excellent wear resistance even in environments with minimal lubrication. Finally, it exhibits very low levels of deformation and creep even under sustained stress.

Chemical & Environmental Resistance

Torlon has excellent resistance to chemical attack, including automotive fluids, solvents, and hydraulic oils, and good resistance to hydrolysis.

Performance of Torlon Bearings

Load-Carrying Capacity

Its excellent compressive strength means that Torlon bearings can be used in high-load bearing applications, with PV ratings up to 100,000 for Torlon 4435.

Temperature Performance

Torlon bearings maintain excellent structural and wear performance even under continuous high temperatures. It is suitable for operating conditions where metal bearings seize.

PV (Pressure–Velocity) Capability

The high PV capability of these bearings makes them well suited for high-speed, high-load applications where heat generation is significant. For example …

  • Torlon 4435
    • Max P (Pressure): 1,000 psi
    • Max V (Velocity): 850 sfm
    • Max PV: 100,000 (psi·ft/min)
    • Service Temperature: 500°F
  • Torlon 4301
    • Max P (Pressure): 1,000 psi
    • Max V (Velocity): 900 sfm
    • Max PV: 50,000 (psi·ft/min)
    • Service Temperature: 500°F

Wear and Friction Behavior

Because these bearings have such a low coefficient of friction, startup wear and energy losses are very low, and they exhibit excellent dry-running performance. In addition, friction is stable across a wide range of loads and temperatures.

Dimensional Stability & Creep Resistance

Low thermal expansion and minimal creep make Torlon bearings an excellent option for precision applications, tight clearances, and long service life.

Applications for Torlon Bearings

Torlon bearings are used in aerospace systems such as flap actuators and landing gear, where low weight, high wear resistance, and the ability to withstand extreme thermal cycling are essential. In oil and gas equipment, Torlon provides reliable performance in HPHT environments for components like downhole tools, pumps, and valves. Industrial machinery relies on Torlon for bushings, wear rings, and thrust washers that offer low friction and long life, where metal bearings wear out quickly.

In automotive and transportation systems, Torlon supports transmissions, pumps, and electric motors with strong thermal resistance and low wear. Semiconductor and precision equipment benefit from Torlon’s low outgassing, chemical resistance, and dimensional stability in clean, tightly controlled environments. Automation and robotics use Torlon bearings in high-load joints and guides, where strength, low wear, and minimal lubrication improve system reliability.

Conclusion

Torlon bearings offer unique advantages for extreme mechanical, thermal, and environmental operating conditions. Their high load capacity, excellent wear behavior, superior PV performance, and broad industrial applicability have made them the choice for many bearing solutions across a range of industries and applications. If you are interested in bearing solutions for aggressive operating environments, contact Advanced EMC today for custom Torlon bearing design, material selection, and manufacturing guidance.

Torlon PAI Molecule
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Torlon Bearings: The Unsung Heroes of High-Load, High-Temperature Mechanisms

Torlon bearings handle extreme loads and high heat in applications where metals and other polymers simply cannot maintain their performance. Made from ultra-strong polyamide-imide (PAI), Torlon bearings can maintain dimensional stability and low friction even under extreme stressors. 

This blog post explores why Torlon bearings excel in such demanding environments, the grades they are available in, what sets them apart from other high-performance materials, and the manufacturing options available.

What Makes Torlon Different: A Polymer Built for Extremes

Torlon PAI (Polyamide-Imide) is a thermoset aromatic imide-amid polymer that was initially developed for its ultra-high molecular strength but also possesses excellent thermal performance and wear resistance. 

Torlon offers continuous service temperature of up to ~500°F (260°C) with minimal creep or softening, and remains stable even when exposed to fuels, lubricants, and most industrial fluids. Torlon has low friction and does an excellent job of resisting wear against both metal and polymer counterparts. These and other properties make Torlon an excellent choice for demanding bearing environments.

Bearing Design Challenges in High-Load, High-Temperature Mechanisms

Common challenges in these environments include high PV conditions, lubrication starvation, wide temperature swings, and thermal cycling issues. All of these issues are met head-on by Torlon bearings.

There are many harsh environments that require high-load, high-temperature bearings, such as jet engine accessory drives, gear pumps, and compressors. And Torlon excels in situations where metals are prone to seize or gall, and polymers may creep or deform. From industrial ovens to downhole drilling tools, electric motors to high-speed aerospace actuators, Torlon has proven itself to be an excellent bearing solution. 

Why Torlon Bearings Excel Under Pressure

Load Capacity and Strength

Torlon possesses a compressive strength that exceeds 35,000 ksi and is able to maintain stiffness even at elevated temperatures, both of which make it excellent for static and dynamic bearing loads. It is also able to retain its mechanical integrity at temperatures beyond 250°C, as well as resisting thermal fatigue and maintaining appropriate clearances in mixed-material assemblies. 

Torlon is naturally self-lubricating, and its coefficient of friction can be further enhanced through  internal fillers like graphite and/or PTFE. It also exhibits excellent wear rates even in dry or marginally lubricated conditions. Its low coefficient of thermal expansion improves alignment and minimizes vibration in high-speed systems. Its low coefficient of thermal expansion improves alignment and minimizes vibration in high-speed systems.

Finally, Torlon components can be injection molded, compression molded, and machined, with exceptional machinability for attaining extremely tight tolerances. 

Grades and Configurations for Torlon Bearings

There are several bearing grades of Torlon available, with various fillers that each enhance key properties. These are summarized in the table below.

GradeFiller TypeKey PropertiesTypical ApplicationsPerformance Notes
Torlon 4203UnfilledHighest purity and electrical properties; moderate wearElectrical connectors, insulatorsBaseline for comparison; not optimized for bearing use
Torlon 430112% Graphite, 3% PTFEExcellent wear resistance and low friction; maintains strength and dimensional stabilityBushings, thrust washers, compressor bearingsIndustry standard bearing grade; performs well under dry or marginally lubricated conditions
Torlon 4435Carbon Fiber + PTFESuperior load-bearing and wear performance; higher modulus and thermal conductivityHigh-load bearings, gears, seal ringsImproved heat dissipation and rigidity; reduced thermal expansion
Torlon 4645Carbon Fiber + Graphite + PTFEMaximum wear and load capacity; top-tier strength and PV limitAerospace bearings, downhole tools, turbocharger bushingsBest balance of strength, wear resistance, and temperature endurance among all grades


Comparing Torlon Bearings to Metal and Other Polymers

Compared to their metal counterparts, Tolon bearings are going to be lighter, corrosion-free, have no galling, lower noise, and reduced lubrication demand. And when compared to higher grades of PEEK and PPS, it retains stiffness and strength even at elevated temperatures and exhibits better dimensional control both under heat and load.

There are, however, tradeoffs. Torlon does cost more, and the molding process is going to be more complicated, but this can be justified because of its reliability and longer service life.

Manufacturing and Machining Considerations

Because Torlon has such a high glass transition temperature (≈280°C), it requires careful molding and post-curing. Compression molding can be used and works exceptionally well for large or thick cross-section bearings where uniform density is critical. Injection molding is another option, and it is ideal for high-volume, precision components with fine detail. While Torlon can be machined, it requires very sharp tooling and the use of coolant, all due to the hardness of the material. In addition, Torlon may require post-curing and stress relief.

The Hidden Value: Reliability and Lifecycle Cost

Including Torlon bearings in a design often means extending the MTBM (Mean Time Between Maintenance) due to reduced wear and a reduced risk of seizure. They also mean a lower cost of ownership compared to metal or standard polymer polymers that usually require much more frequent replacements. In addition, Torlon bearings are a lightweight, reduced-lubrication solution that enhances energy efficiency.

Conclusion

Torlon bearings are critical to high-performance machinery, delivering excellent reliability where strength, heat resistance, and dimensional stability are necessary. Capable of withstanding extreme loads and temperatures that would cause metals to seize and conventional polymers to deform, they provide unmatched durability in the most demanding environments. 

Advanced EMC engineers will help you design and manufacture precision Torlon bearing solutions for aerospace, industrial, and energy applications where reliability is not optional and loads are high. Contact our knowledgeable team to discuss your next high-performance bearing challenge.