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.

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Machined and Molded Polymer Bearings: Nylon 66, PEEK, and PPS

Nylon 66, PEEK, and PPS are available in bearing grades, but how should they be manufactured? The choice of manufacturing method can have a significant impact on their tolerances, performance, and cost. 

This blog post focuses on machined and molded polymer bearings, including their benefits and limits, how they compare to metal options, and the best ways of manufacturing bearings made from three very different materials: Nylon 66, PEEK, and PPS. 

Introduction to Polymer Bearings

Polymer bearings are low-friction, lightweight alternatives to traditional bearings. They are corrosion-resistant and offer varying degrees of chemical resistance. Polymer bearings are also known for their ability to run dry or with minimal lubrication, as well as good wear characteristics. They are also electrically insulating and offer quieter operation than their metal counterparts.

However, polymer bearings do have their limits. They are more susceptible to thermal expansion and may have lower load limits and PV than their metal counterparts, but the addition of fillers can mitigate this issue. In some cases, they may be susceptible to moisture uptake. 

The table below summarizes the major differences between metal and polymer bearings.

Metal vs Polymer Bearings

FeatureMetal BearingsPolymer Bearings
FrictionLow only with lubricationLow due to inherent lubricity
LubricationRequiredOften not required
Wear MechanismAbrasive/adhesive fatigueTransfer film formation
CorrosionPossibleNearly immune
Shock/VibrationNo dampingNatural damping
SpeedHighModerate
LoadHigherModerate
Temperature LimitsExcellentVaries by polymer
MaintenanceHigherVery low

Machined vs. Molded Polymer Bearings

Machined bearings are best for small production runs where tight tolerances and complex geometries are involved, and machining is ideal for prototypes, custom components, and specialty rotating equipment. This approach to manufacturing bearings also allows the material to remain homogenous with no molded-in stresses.

Molded bearings are the best option for high-volume production, and they are more cost-effective for simpler geometries. Molding also means reduced part-to-part variation; however, molded-in stress may be present, and there are limits to surface finish.

When choosing between machined and molded polymer bearings, the key factors are:

  • Geometry
  • Tolerances
  • Cost
  • Production volume

Nylon 66, PEEK, and PPS

Among the various options for polymer bearings are Nylon 66, PPS, and PEEK. The table below summarizes the differences between these materials.

Performance Comparison: Nylon 66 vs. PPS vs. PEEK

Property / FactorNylon 66PPSPEEK
Max Continuous Use Temperature~100–120°C~200–220°C~240–260°C
Wear ResistanceGood (improved with lubrication)Very goodExcellent (especially filled grades)
FrictionLowLowVery low
Moisture AbsorptionHigh (can swell, affects tolerances)Very lowVery low
Dimensional StabilityModerate (affected by humidity)HighVery high
Chemical ResistanceModerateExcellentExcellent
Mechanical StrengthGoodHighVery high
Impact ResistanceVery goodModerateGood
Creep ResistanceModerateGoodExcellent
PV CapabilityLow–MediumMedium–HighHigh–Very High
CostLowMediumHigh
Machining SuitabilityExcellentExcellentExcellent (best with filled grades)
MoldabilityExcellentGoodGood
Typical ApplicationsRollers, appliance bearings, automotive interior componentsPumps, compressors, chemical processing, precision housingsAerospace, oil & gas, high-speed bearings, semiconductor tools

Manufacturing Nylon 66, PEEK, and PPS Bearings

There are several different bearing materials available, but of interest in this blog post are Nylon 66, PPS, and PEEK bearings.

Nylon 66

Nylon 66 is very easy to mold because of its low viscosity, forging processing window, and good flow characteristics. However, there is going to be high mold shrinkage, which requires careful part design to keep warpage under control. Nylon also absorbs moisture, which means that drying is important before molding takes place. 

Nylon also machines easily, but its high ductility leads to stringy chips that necessitate the use of chip-breakers. Heat buildup is also an issue with nylon, and moisture absorption can impact the level of precision that can be achieved. It does, however, respond well to secondary machining on already molded parts, but does not work well with tight-tolerance CNC components.

PEEK

Because PEEK high a high melt temperature around 343°C, a very narrow thermal window that requires precision temperature control, and requires a heated mold, it is considered challenging to mold. However, with the right processing parameters and careful design, PPS can be molded and can manufacture parts with excellent thermal and mechanical performance (but is more expensive). 

PEEK is very difficult to machine. Its high modulus and hardness make it especially tough on cutting tools, and reinforced grades can be highly abrasive. It also generates an abundance of heat, thus requiring the use of coolants. However, machining PEEK supports excellent tolerances and surface finishes when the right combination of feed and speed is used. In fact, PEEK is frequently machined for low-volume aerospace and medical components.

PPS

PPS is not as easy to mold as Nylon 66 because its melt temperature is higher, it possesses a narrower processing window, and has high viscosity. However, it does exhibit very low shrinkage and excellent dimensional stability. PPS molding is very predictable and an excellent option once the right processing parameters have been figured out.

PPS is machinable, definitely more so than Nylon, but tends to be more brittle. It produces short chips and there is a risk of edge chipping during more aggressive cuts. On the other hand, it is good for tight tolerances. Note that filled grades of PPS can accelerate tool wear. Machining PPS is ideal for high-precision parts where dimensional stability is important.

Conclusion

Machined and molded Nylon 66, PPS, and PEEK bearings continue to gain traction because of properties such as low friction, wear characteristics, damping, corrosion resistance, and chemical compatibility. If you are in need of polymer bearings, Advanced EMC is here to help. Our team of engineers and bearing experts can help you from initial design to manufacturing to testing. Contact us today to learn more.