At Craftech, we make plastic bearings in a wide variety of materials, some of which perform better than others. For a high performance plastic bearings, three of the best materials to use are Vespel®, Torlon® . and PEEK. Let’s take a closer look at these to see what makes them ideal bearing materials.

 Vespel®

Vespel® by DuPont is the name of a range of high performance polyimide-based plastics. This material is one of the most expensive materials on the market. It provides high performance solutions for the most difficult sealing, wear or friction applications.   Vespel®’s strong performance in high friction applications makes the material an ideal choice for plastic bearings. It can also endure high temperatures and stand up to the most difficult operating conditions known on the planet and even in space.

As Vespel® is also light in weight, parts made of this material can make it a better alternative than metal, standard ceramics or other engineering plastics when weight is an issue. However, the material tends to absorb a small amount of water. Thus this results in a longer pump time when placed in a vacuum. Unlike most, it does not outgas even at high temperatures thus it performs well in vacuum applications.

Additionally, Vespel® performs well down to extremely low cryogenic temperatures. Vespel® has it all. It has heat resistance, lubricity, dimensional stability, chemical resistance and creep resistance and performs well in extreme environments. There are others that can surpass Vespel® in individual aspects. However, it is the combination of all Vespel’s® properties that gives it an overall advantage. Vespel® is used to make automotive parts, centrifugal pump parts, custom plastic parts, transportation, aircraft engine and reverser parts, actuator guide bushings and many other parts for applications in harsh environments in addition to plastic bearings.

Torlon®

Torlon® is a high performance amorphous (non-crystalline) engineering thermoplastic with a glass transition temperature of 537°F (280°C). Chemically, Torlon® is a polyamide-imide (PAI), a reaction product of trimellitic anhydride and aromatic diamines. It is called amide-imide because the polymer chain comprises amide linkages alternated with imide linkages. Torlon has a continuous service temperature of 500°F (260°C) and has greater compressive strength and higher impact resistance then most advanced engineering plastics.

The down side of working with Torlon® is that, as it is made of nylon and Vespel® it tends to absorb water. Also, Torlon® is not a good choice for a bearing caged in a vacuum application as it will “out-gas” and contaminate the environment. Torlon’s® mechanical properties are best maintained when it is injection molded although it can be compression molded as well. It is used mostly in aerospace bearings. It has been shown that Torlon® performs better than PEEK or Vespel® in oxygen rich plasma processing conditions. Torlon® is an excellent choice for plastic bearings in the latter application.

PEEK Polyetheretherketone

Bearing grade PEEK is known for its excellent wear characteristics, good abrasion resistance, and extremely low coefficient of friction. This plastic has extraordinary mechanical and chemical properties as well as excellent wear resistance. It has excellent sliding properties which results in a low coefficient of friction. Certain parts made of PEEK can operate without lubricants. It is also easy to machine, has low moisture absorption, and possesses a high PV

Also it is flame retardant with a V-0 burn rate. Additionally it is not affected by water and can maintain excellent properties in high temperature and in high pressure water conditions. PEEK has a continuous operating temperature of 260 °C/500 °F and is also radiation resistant.

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