What Is PEEK and What Makes It Different?
PEEK stands for polyether ether ketone, a semi-crystalline aromatic thermoplastic first commercialized in the early 1980s. Its aromatic backbone structure gives it exceptional thermal stability, resistance to a broad spectrum of chemicals, and mechanical properties retained at temperatures where most engineering plastics have softened or degraded.
PEEK is available as: unfilled natural (tan/beige), carbon-fiber-filled for enhanced stiffness, glass-fiber-filled for dimensional stability under load, and bearing-grade with PTFE and graphite for reduced friction. Plastic-Craft stocks all grades with no minimum order.
Key Properties That Justify the Cost
Continuous service temperature: Up to 480°F (250°C) — far beyond nylon, Delrin, or polycarbonate.
Chemical resistance: Resistant to virtually all organic and inorganic chemicals including concentrated acids, alkalis, hydrocarbons, and steam.
Mechanical strength: High tensile strength, excellent fatigue resistance, outstanding creep resistance under sustained load — all retained at elevated temperatures.
Dimensional stability: Less than 0.5% moisture absorption — exceptional stability across varying humidity and temperature.
Radiation resistance: Withstands high levels of gamma and X-ray radiation — key for medical, nuclear, and semiconductor.
Flame resistance: Inherently flame-retardant (LOI 35%), self-extinguishing without additives. Suitable for aerospace fire safety.
Machinability: Machines to tight tolerances with standard carbide tooling.
PEEK's one notable limitation is cost. The correct engineering decision is to specify PEEK only when the application genuinely requires its specific combination of high-temperature performance, chemical resistance, and dimensional stability. When one or two of those requirements can be met by a lower-cost material, the premium is not justified.
Where PEEK Gets Specified
Aerospace: Brackets, seals, bushings where weight reduction, flame resistance, and extreme temperature performance are simultaneous requirements.
Medical: Implantable components, surgical instruments, sterilizable housings requiring biocompatibility, radiation resistance, and autoclave compatibility.
Oil and gas: Valve seats, pump components, downhole equipment surviving aggressive hydrocarbons at high pressure and temperature.
PEEK Grades
Standard for most medical, semiconductor, and general high-temperature applications. Maximum chemical resistance and dimensional stability.
Added stiffness and thermal conductivity for structural components under high sustained loads. Reduced impact resistance.
Improved dimensional stability and compressive strength for precision structural applications.
PTFE and graphite filled for significantly reduced friction in dry-running bearing and seal applications.
Frequently Asked Questions
What temperature can PEEK withstand?
Continuous service up to 480°F (250°C). Retains mechanical properties and dimensional stability at temperatures where nylon, Delrin, and polycarbonate have already failed.
Is PEEK biocompatible?
Yes. Unfilled PEEK is biocompatible and widely used in implantable medical devices. Withstands autoclave, gamma radiation, and EtO sterilization. Medical-grade stock requires certified traceability.
How does PEEK compare to Ultem?
PEEK offers higher continuous service temp (480°F vs 340°F), broader chemical resistance, and better fatigue performance. Ultem is less expensive with better inherent flame retardance and transparency. PEEK for the most demanding environments; Ultem when cost is a factor and chemical exposure is moderate.
What are the different PEEK grades?
Unfilled (general purpose), carbon-fiber-filled (maximum stiffness), glass-fiber-filled (dimensional stability), bearing-grade with PTFE/graphite (low friction). Grade depends on load, temperature, friction, and chemical exposure.
Where can I buy PEEK?
Plastic-Craft Products stocks unfilled and filled PEEK in rod, sheet, and tube at West Nyack, NY. No minimum orders. Call (845) 358-3010 or email [email protected].
Ready to Order PEEK Rod, Sheet, or Tube?
Plastic-Craft stocks unfilled and filled PEEK in a full range of sizes and grades — cut to exact dimensions or machined to print with no minimum orders and ISO/AS9100D certified quality.
(845) 358-3010