Peek - Materials - Technical
Small Parts and Bearings
Polyether ether ketone (PEEK®) is a colourless organic polymer thermoplastic used in engineering applications.
PEEK® is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained to high temperatures. The Young’s modulus is 3.6 GPa and its tensile strength 90 to 100 MPa. PEEK® has a glass transition temperature at around 143 °C (289 °F) and melts around 343 °C (662 °F). The thermal conductivity increases nearly linearly versus temperature between room temperature and solidus temperature. It is highly resistant to thermal degradation as well as attack by both organic and aqueous environments. It is attacked by halogens and strong Bronsted and Lewis acids as well as some halogenated compounds and aliphatic hydrocarbons at high temperatures. It dissolves completely in concentrated sulfuric acid at room temperature.
Because of its robustness, PEEK® is used to fabricate items used in demanding applications, including bearings, piston parts, pumps, HPLC columns, compressor plate valves, and cable insulation. It is one of the few plastics compatible with ultra-high vacuum applications. PEEK® is considered an advanced biomaterial used in medical implants. It is extensively used in the aerospace, automotive, teletronic,[clarification needed] and chemical process industries. PEEK®’s mechanical properties at elevated temperatures have led to it being used in at least two varieties of Reprap extruder as thermal insulation. This means the rest of the extruder structure can be made of the same material as the object being fabricated without self-destruction. A disadvantage is the high price, which limits its application to high value items.
This general purpose grade is unreinforced and offers the highest elongation and toughness of all PEEK® grades. Unfilled PEEK® is available in sheet and rod forms in natural (a very light brown or tan) color (see photo above) and is also available in black . Black PEEK® is ideal for instrument components where aesthetics are important, as well as for seal components where ductility and inertness are important. All unfilled PEEK® grades comply with FDA regulation 21 CFR 177.2415 for repeated food contact.
PEEK® (30% Glass Filled)
The addition of glass fibers significantly reduces the expansion rate and increases the flexural modulus of PEEK®. This grade is ideal for structural applications that require improved strength, stiffness, or stability, especially at temperatures above 300°F (150°C). Glass-filled PEEK® is light brown or tan in color.
PEEK® (30% Carbon Filled)
The addition of carbon fibers enhances the compressive strength and stiffness of PEEK®, and dramatically lowers its expansion rate. It offers designers optimum wear resistance and load carrying capability in a PEEK®-based product. This grade provides 3½ times higher thermal conductivity than unreinforced PEEK® -- dissipating heat from the bearing surface faster. Carbon-filled PEEK® is black in color.
PEEK® (Bearing Grade, Ketron HPV)
This grade of PEEK®, containing carbon fiber reinforced with graphite and PTFE lubricants, offers the lowest coefficient of friction and the best machinability for all PEEK® grades. Bearing grade PEEK® has an excellent combination of low friction, low wear, high limiting PV, low mating part wear, and easy machining. Bearing grade PEEK® is black or dark grey in color.
TYPICAL PROPERTIES of EXTRUDED PEEK®
(compression molded and injection molded versions also available) updated 19May2008
|ASTM or UL test||Property||Unfilled||30% Glass Fibers||30% Carbon Fibers||Bearing Grade|
|D570||Water Absorption, 24 hrs (%)||0.10||0.10||0.06||0.05|
|D638||Tensile Strength (psi)||16,000||15,000||19,000||11,000|
|D638||Tensile Modulus (psi)||500,000||900,000||1,100,000||850,000|
|D638||Tensile Elongation at Break (%)||20||3||5||2|
|D790||Flexural Strength (psi)||25,000||28,000||25,750||27,500|
|D790||Flexural Modulus (psi)||600,000||1,000,000||1,250,000||1,100,000|
|D695||Compressive Strength (psi)||20,000||26,000||29,000||26,700|
|D695||Compressive Modulus (psi)||500,000||1,000,000||-||1,000,000|
|D785||Hardness, Rockwell||M100 (R126)||M103||M102||M85|
|D256||IZOD Impact Notched (ft-lb/in)||1.0||1.4||1.0||0.7|
|D696||Coefficient of Linear Thermal Expansion
(x 10-5 in./in./°F)
|D648||Heat Deflection Temp (°F / °C)
at 264 psi
320 / 160
600 / 315
550 / 288
383 / 195
|D3418||Melting Temp (°F / °C)||644 / 340||644 / 340||644 / 340||-|
|-||Max Operating Temp (°F / °C)||480 / 249||480 / 249||500 / 260||482 / 250|
(x 10-4 cal/cm-sec-°C)
|D149||Dielectric Strength (V/mil) short time, 1/8" thick||480||500||32||-|
|D150||Dielectric Constant at 1 MHz||3.30||3.70||-||-|
|D150||Dissipation Factor at 1 MHz||0.003||-||-||-|
|D257||Volume Resistivity (ohm-cm) at 50% RH||4.9 x 1016||5 x 1016||105||103|
NOTE: The information contained herein are typical values intended for reference and comparison purposes only. They should NOT be used as a basis for design specifications or quality control. Contact us for manufacturers’ complete material property datasheets.PEEK® is a trademark of Victrex USA, Inc.
All values at 73°F (23°C) unless otherwise noted.
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