Plastics for Friction and Wear Applications

Low-friction, long-wearing plastic materials perform well in bearing applications

A number of different plastics generally perform well in friction and wear applications, and are often used in bearings, bushings, gears, and chain guides. These materials include: 

•    UHMW
•    Nylon
•    Acetal 
•    PET (semicrystalline)
•    PBT
•    PPS
•    PEEK
•    DuPont™ Vespel®

 

Low-friction additives such as PTFE, oil, carbon fiber, and graphite powder can also significantly improve the wear performance of these polymers under certain conditions. It’s important to recognize that wear is a complex behavior that may include adhesion, abrasion, erosion and/or fatigue. A particular plastic may have excellent wear characteristics under one set of conditions, and poor wear behavior under other conditions. At Curbell, our technical experts can help you consider numerous factors that can affect performance, including the operating temperature range, the degree of outdoor exposure, the mating surface, and the presence of water or other chemicals. For assistance choosing the right plastic material for use in a friction and wear application, please contact us today. 


Sliding wear against mating metal parts

Plastics such as UHMW, nylon, and acetal are excellent choices for wear applications that involve sliding against mating metal parts. Many of these materials are available in formulations that include additives and fillers to further enhance their sliding wear performance.

Filled polymers with outstanding friction and wear characteristics include:

  • LubX® C enhanced wear UHMW
  • Delrin® AF
  • TECAFORM® HPV13
  • Nycast® GX
  • Internally lubricated semicrystalline PET
  • TECAPEEK® PVX
  • Dupont™ Vespel® SP-21, SP-211, SCP-5050, and SCP-50094


Wear in gritty, abrasive conditions

Plastics that perform well in abrasive wear applications - UHMW, Matrox® UHMW, special grades of thermoset polyurethaneSome wear environments include abrasive particles coming into contact with the plastic wear surface. Examples include bulk material handling applications (such as hoppers and conveyor lines) where sand, sugar, coal or other abrasive materials are moved throughout a production process. Gritty particles can also accelerate wear in sliding applications if dirt, sawdust, or other contaminants are present. Particle abrasion presents a special challenge for machinery designers since plastic materials that wear well in “clean” bearing conditions may exhibit excessive wear in these abrasive environments.

Materials that perform well in many abrasive wear applications include:

  • UHMW
  • Matrox® enhanced wear performance UHMW
  • Special grades of thermoset polyurethane


Wear in extreme temperature environments

Vespel® for high temperature wear applicationsHigh temperature wear applications require polymers that maintain a significant portion of their room-temperature mechanical properties when exposed to elevated temperatures. It is also important that a high temperature plastic wear material have a relatively low coefficient of thermal expansion, particularly if the polymer is to be used in direct contact with mating metal parts. 

Plastics that are engineered for use in high temperature friction and wear applications include:

  • Tecatron® PVX
  • TECAPEEK® PVX
  • DuPont™ Vespel® SP-21 and SP-211
  • DuPont™ Vespel® SCP-5050 and SCP-50094

Wear applications involving extremely cold environments can also be challenging, since plastics generally become more brittle in cold temperatures. Plastics also tend to have higher rates of thermal contraction compared with metals, which can cause plastic parts to go out of tolerance (excessively shrink) at cryogenic temperatures. However, a number of plastic materials—including filled grades of PEEK and DuPont™ Vespel® have superior dimensional stability and cold temperature ductility. These plastics have been successfully used in friction and wear applications at cryogenic temperatures.

Material wearing out? We can help.

Whether you need plastic parts that last longer in extreme temperatures, abrasive conditions, or sliding applications, our technical experts can suggest materials, and help you solve your material challenges. To learn more about the full range of plastics designed for friction and wear applications, please contact us today. 

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Frequently Asked Questions
Do all plastic materials have good wear characteristics?

Many semicrystalline plastics such as nylon, acetal, and PEEK have good wear characteristics, which can be further enhanced via the addition of additives and fillers. Some thermosetting plastics including polyurethanes and friction and wear grades of DuPont™ Vespel® shapes also perform well in wear applications. Amorphous plastics such as ABS, polycarbonate, and acrylic have limited friction and wear capabilities.

Which material properties should be considered when selecting a plastic for a friction and wear application?

It is important to evaluate the coefficient of friction, wear rate, and pressure velocity limitations of the material. It is also important to consider the coefficient of thermal expansion of the plastic, particularly if it is to be used in contact with a mating metal part. Finally, it is important to evaluate the material’s ability to perform in the operating environment including low and high temperatures, UV or other radiation exposure, and in the presence of water or other chemicals.

What are the best friction and wear materials for high temperature environments?

Tecatron® PVX polyphenylene sulfide and TECAPEEK® PVX polyetheretherketone are both outstanding choices for many high temperature bearing applications. DuPont™ Vespel® SP-21, SCP-5050, and SCP-50094 are also outstanding materials for high temperature friction and wear parts.

What are the best friction and wear materials for use in gritty, abrasive conditions?

UHMW and certain grades of thermoset polyurethane perform particularly well in many sliding wear and bulk material handling applications that involve contact with gritty abrasive particles.  

Are there any friction and wear plastics that function well in vacuum environments?

Vacuum conditions present a particular challenge for friction and wear plastics since graphite additives, which normally lower the coefficient of friction of plastic materials, become abrasive in dry or vacuum environments. That being said, there are special non-graphite formulations such as DuPont™ Vespel® SP-3 that are engineered for friction and wear applications that involve vacuum conditions.