The four top grades of PEEK are: unfilled, 30% glass-filled, 30% carbon-filled, and 20% PTFE and graphite filled. These materials are manufactered into fasteners and components such as bearings, screws, flat washers, hex nuts, gears, and medical components in addition to many custom shapes. The properties of each and the industries they are used in are discussed below.
Of the top four grades of PEEK, unfilled-PEEK (polyetheretherketone) is the most common grade. It is a semi-crystalline polymer. That means it has a distinct melting point. Its melting point is 646°F (341°C.) Also, it has a continuous service temperature of 500°F (260°C.) Its low temperature is -40ºC When exposed to flame, natural PEEK emits little smoke or toxic gas. PEEK has a rating of UL 94V-0. This material is resistant to boiling water and super heated steam such as would be found for instance in an autoclave for sterilization purposes in the medical industry.
Unfilled-PEEK exhibits low creep and very low moisture absorption and is stress crack and abrasion resistant. It also is unaffected by radiation and has the best fatigue resistance of all the PEEK grades.
Unfilled-PEEK is highly chemical resistant to a wide range of solvents, organics, salts and bases. In the semiconductor industry its high chemical resistance is valued in the manufacture of ICUs in vacuum chambers.
This grade of PEEK has very high purity. It is FDA approved for repeated contacts with food. Unfilled PEEK comes in a variety of colors in applications where aesthetics are important.
It is used in the oil and gas industry as well as the aerospace, food and beverage, marine, automotive and nuclear industries. In particular it is used to make thrust washers, bushings, valve plates, high load bearings, and additionally compressor and pump components.
30 % glass-filled PEEK
This grade is unfilled PEEK with 30% glass fiber mixed in. This grade offers higher strength and stiffness over the unfilled grade. It is particularly useful in applications where a continuous service temperature approaching (300°C) is required. The down side is that it wears more on mating parts. 30% glass-filled PEEK comes in natural and black.
As mentioned above glass-filled PEEK is used in the oil and gas industries where steam and chemicals are encountered in an application. It will also provide extra strength and stiffness.
30% Carbon-filled PEEK
This grade of PEEK has 30% carbon-filled fibers added to it. The compressive strength and stiffness of the material is enhanced. And as a result its expansion rate is dramatically lowered. It is the grade with the optimum wear-resistance and load carrying characteristics. 30% carbon-filled PEEK has greater thermal conductivity than unfilled PEEK. It is made into bearings and allows for more heat dissipation from the bearing surface. As a result the life and performance of the part are increased. This grade comes in black.
20% PTFE-filled PEEK
This grade of PEEK is often referred to the “bearing grade.” And because it is filled with 20% PTFE and carbon reinforced with graphite, this grade has the lowest coefficient of friction of all the grades. As a result, it is ideal for applications in which low friction, low wear, high LPV and low mating part wear are desirable. Therefore, it is often used to make bearings in many industries.
Craftech Industries, Inc. is a manufacturer of custom parts, bearings and fasteners such as screws, hex nuts, flat washers in a wide range of plastics.