PEEK FAQ: 14 Common Questions Answered
PEEK (polyether ether ketone) is one of the highest-performing thermoplastics available as a semi-finished stock shape. Engineers and buyers frequently encounter the same questions — about sterilization limits, FDA status, grade selection, and cost — when specifying it for the first time. This FAQ covers the most common questions about PEEK sheet, rod, and tube in plain, direct language.
What is PEEK?
PEEK stands for polyether ether ketone, a semi-crystalline aromatic thermoplastic in the polyaryletherketone (PAEK) family. It was commercialized in the 1980s and has become the go-to material when engineers need continuous service above 300°F (149°C), excellent chemical resistance, inherent flame resistance, and high strength-to-weight ratio — all in a machinable stock shape. It is available as extruded rod, sheet, and tube, as well as injection-molded parts. For a full property breakdown, see the PEEK material hub.
Is PEEK FDA approved for food contact?
Unfilled, natural (tan/beige) PEEK meets FDA 21 CFR 177.2415 for repeated food-contact use. This covers direct-contact applications such as food-processing machine parts, conveyor components, and packaging equipment. However, "FDA compliant" is a self-declaration — the resin manufacturer (Victrex, Evonik, Solvay) provides letters of compliance; the finished part manufacturer must confirm that no non-compliant additives were introduced during machining or fabrication. Glass-filled and carbon-filled grades are generally not food-contact compliant unless specifically tested.
How does PEEK compare to Ultem (PEI)?
PEEK and Ultem PEI are the two most commonly confused high-performance thermoplastics. PEEK has a higher continuous use temperature (480°F vs. 340°F), better chemical resistance to hydrocarbons, and higher fatigue strength — making it the first choice for aggressive environments. Ultem is stiffer at room temperature, costs roughly 30–50% less, and has a slightly better inherent flame rating (UL94 V-0 at thinner gauges). For applications under 300°F where cost and stiffness matter more than chemical resistance, Ultem may be the better pick. See the full PEEK vs. Ultem comparison for a property-by-property breakdown.
What does PEEK cost compared to other engineering plastics?
PEEK is among the most expensive commodity thermoplastic stock shapes. Natural unfilled PEEK rod or sheet typically runs $80–$200 per pound at distributor pricing, depending on form factor and quantity. By comparison, Delrin (acetal) runs $5–$12/lb and Ultem $25–$60/lb. The cost premium is justified when no lower-cost material can meet the combined thermal, chemical, and mechanical requirements. For large production runs, consider whether injection-molded PEEK parts (using regrind-tolerant grades) can reduce material waste compared to machining from rod stock.
What is PEEK's continuous use temperature?
Unfilled PEEK is rated for continuous use at 480°F (250°C) and short-term excursions up to approximately 572°F (300°C). This makes it suitable for steam environments, down-hole oil and gas service, and aerospace components that see sustained elevated heat. The glass transition temperature (Tg) is 289°F (143°C), but the semi-crystalline structure means PEEK retains useful mechanical properties well above Tg — a key advantage over amorphous polymers like Ultem. Refer to the PEEK properties page for the full thermal data table.
What PEEK grades are available — 450G, GF30, CF30?
Three unfilled and filled grades dominate stock shape supply:
- 450G (unfilled): The baseline Victrex grade — 14,500 psi tensile strength, 1.32 g/cc density. Used when FDA compliance, biocompatibility, or electrical insulation is required.
- GF30 (30% glass-filled): Higher stiffness (flexural modulus ~1,100 ksi vs. ~550 ksi unfilled), lower CLTE, better creep resistance. Use when dimensional stability under sustained load is critical.
- CF30 (30% carbon-filled): Highest stiffness and strength of the three (~1,600 ksi flexural modulus), significantly lower CLTE (~1.0×10⁻⁵ in/in/°F), and self-lubricating — ideal for wear-intensive bearing and bushing applications.
Other grades include ESD-safe and bearing-grade formulations. For a detailed grade comparison, see the PEEK grades guide.
Is PEEK easy to machine?
Yes — PEEK machines cleanly with standard carbide tooling using conventional CNC equipment. Use sharp tooling, moderate feeds (0.002–0.005 in/rev), high speeds (500–1,000 SFM), and compressed air or mist coolant rather than flood coolant. Avoid excessive heat buildup, which can cause thermal stress in tight-tolerance parts. Unfilled PEEK produces short, manageable chips. Glass-filled and carbon-filled grades are mildly abrasive — expect faster tooling wear and plan for more frequent insert changes. Annealing extruded rod before machining close-tolerance parts reduces residual stress. The PEEK machining guide covers feeds, speeds, and fixturing in detail.
What are the benefits of glass-filled PEEK (GF30)?
Glass-filled PEEK (GF30) adds 30% short glass fiber to the base resin. The primary benefits are: (1) higher flexural modulus (~1,100 ksi vs. ~550 ksi unfilled) for applications requiring greater stiffness under load; (2) reduced coefficient of linear thermal expansion (CLTE ~1.5×10⁻⁵ in/in/°F vs. ~2.6×10⁻⁵ unfilled), which matters when PEEK is assembled against metal in thermally cycled environments; (3) improved creep resistance under sustained load at elevated temperature. The tradeoffs are reduced impact strength, loss of FDA food-contact compliance, and mild abrasiveness during machining. GF30 is a common choice for structural brackets, pump housings, and valve seats.
Can PEEK be steam autoclaved?
Yes. Unfilled PEEK is one of the few thermoplastics that withstands repeated steam autoclave cycles at 134°C (273°F). It does not absorb meaningful moisture (water absorption <0.5%) and does not hydrolyze in steam environments. This makes it the material of choice for reusable surgical instruments, endoscope components, and dental device parts that must survive hundreds of sterilization cycles. PEEK also tolerates gamma radiation and EtO sterilization. For a full discussion of PEEK in medical and sterile environments, see PEEK medical implants and device applications.
Is PEEK recyclable?
PEEK is thermoplastic, so it is technically re-meltable and recyclable. In practice, post-industrial PEEK scrap (sprues, offcuts, machining chips) can be reclaimed and reprocessed — some compounders accept it. However, post-consumer PEEK recycling infrastructure is essentially nonexistent; the material is too high-value and too niche for municipal recycling streams. Most machining swarf is collected and sold back to regrind operations. If sustainability reporting is a concern, work with your PEEK supplier to identify a regrind take-back program.
Is PEEK used in medical implants?
Yes, PEEK is widely used in spinal implants, orthopedic spacers, and cranial reconstruction because its elastic modulus (~3.6 GPa) closely matches cortical bone, reducing stress shielding. Implant-grade PEEK (ASTM F2026) requires processing from virgin resin with documented traceability and biocompatibility data per ISO 10993. Standard machining-grade PEEK stock is not implant grade. If you are sourcing PEEK for an implantable device, specify ASTM F2026-compliant material and obtain full lot documentation. Non-implantable medical device applications (instrument handles, housings, trial instruments) can typically use standard 450G stock.
What color options are available for PEEK?
Natural (unfilled) PEEK is tan/beige. Carbon-filled PEEK (CF30) is black. Glass-filled PEEK (GF30) is a slightly darker tan than unfilled. ESD-safe PEEK grades are typically black or dark gray. Pigmented PEEK in custom colors is available from some compounders but requires minimum order quantities and longer lead times — it is rarely stocked off-the-shelf. For most structural and mechanical applications, color is not a functional criterion; specify by grade and lot traceability, not appearance.
What lead times should I expect for PEEK stock shapes?
Standard unfilled and GF30 PEEK rod, sheet, and tube in common sizes is typically in stock at major distributors with same-day or next-day ship capability. CF30 and ESD-safe grades may require 1–3 weeks from specialty distributors. Large-format sheet (>1″ thick, >24″ wide) and tube with non-standard OD/ID combinations can require 4–8 weeks from resin-to-shape converters. For critical-path projects, confirm stock availability at the time of order and request a material cert with your shipment. Visit the PEEK line card to check current stock and request a quote.
Are there industry standards or certifications for PEEK?
PEEK stock shapes are governed by ASTM D6262 (standard specification for PEEK) and Victrex's own product data sheets. Implant-grade PEEK falls under ASTM F2026. Aerospace applications may require compliance with specific AMS or MIL standards depending on the platform. Medical device manufacturers typically require ISO 10993 biocompatibility data and full lot traceability (certificate of conformance plus raw material certs). Most distributors can supply a CoC with each shipment on request. For ESD-sensitive environments, specify the volume resistivity required and confirm it against the grade datasheet.
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Frequently asked questions — Peek FAQ
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