PEEK Plastic — Complete Guide to Sheet, Rod & Tube

PEEK (polyether ether ketone) is the benchmark semicrystalline thermoplastic for applications that demand continuous service at 480°F (250°C), chemical resistance across a broad pH range, and regulatory compliance in medical or food-contact environments. Available as extruded or compression-molded sheet, rod, and tube, PEEK delivers a strength-to-weight ratio that challenges many aluminum alloys — at a fraction of the machining difficulty of exotic metals.

At a glance:

• Continuous use temperature: 480°F (250°C); short-term excursions to 570°F (300°C)
• Tensile strength: 14,500 psi (virgin); up to 29,000 psi in CF30 grade
• Glass transition temperature (Tg): 143°C; crystalline melt point (Tm): 343°C
• FDA 21 CFR 177.2415 compliant; USP Class VI; available in NSF-rated formulations
• GVE (Glow-Wire Vertical, UL 94 V-0 equivalent) flame rating
• Grades: Virgin PEEK, GF30, CF30, ELS (electrostatic), PEEK 450G
• Forms: sheet, rod, tube — natural (tan/beige) and black

What Is PEEK and Why Does It Matter?

Polyether ether ketone belongs to the PAEK (polyaryl ether ketone) family. Its backbone combines ether linkages with ketone groups flanking a central aromatic ring, producing a polymer chain that resists hydrolysis, steam, and most industrial solvents even at elevated temperatures. PEEK crystallizes upon cooling from the melt — typically reaching 30–35% crystallinity in extruded stock — which is what gives it that extraordinary combination of stiffness, creep resistance, and chemical inertness.

Why Engineers Specify PEEK

The appeal is simple: no other unfilled thermoplastic sustains load at 250°C in continuous service. Competing high-performance polymers either fall short on temperature (Ultem/PEI peaks around 340°F continuous), short on chemical resistance (PAI/Torlon is attacked by strong bases), or short on regulatory clearance (some specialty grades lack FDA or USP approvals). PEEK holds all three advantages simultaneously.

For aerospace engineers, PEEK stock shapes meet FAA flame, smoke, and toxicity (FST) requirements in cabin-interior applications. For medical device designers, USP Class VI certification and autoclavability at 134°C make PEEK suitable for sterilizable surgical instruments and implant trial components. Semiconductor fabs rely on PEEK wafer carriers and fixtures because the material has low ionic contamination and withstands H₂SO₄/H₂O₂ piranha etch chemistries at elevated temperatures.

Comparing PEEK to the Next Best Options

PEEK costs more than Ultem PEI and far more than Delrin, but in high-temperature or regulated applications, the engineering premium pays for itself quickly in reduced part failures and qualification overhead. For a side-by-side breakdown, see the PEEK vs Ultem comparison.

PEEK Material Properties

PEEK's mechanical profile is unusually flat with respect to temperature: stiffness (flexural modulus ~600,000 psi) changes only modestly up to about 120°C. Above the Tg of 143°C, amorphous PEEK softens substantially, but crystalline PEEK — the form found in properly processed stock shapes — retains significant load-bearing capacity all the way to the crystalline melt at 343°C.

Mechanical Properties (Virgin PEEK, 73°F)

Thermal Properties

Electrical and Chemical Properties

Virgin PEEK is an excellent electrical insulator with a volume resistivity exceeding 10¹⁶ Ω·cm. ELS (electrostatic) grades bring surface resistivity down to the dissipative range (10⁶–10⁹ Ω·sq) for semiconductor handling equipment. Chemically, PEEK resists all common organic solvents, hydraulic fluids, jet fuels, and acids at or below pH 2. Concentrated sulfuric acid and strong oxidizing environments above 60% concentration are the primary exceptions.

For the complete PEEK properties datasheet, including filled-grade values, see the dedicated properties article.

PEEK Grades

Stock PEEK ships in five primary grades. Grade selection drives both performance and cost:

Virgin PEEK — Pure, unfilled resin. Maximum chemical resistance and FDA clearance. Ideal when cleanliness, biocompatibility, or chemical exposure is the top priority. Translucent tan/natural color.

PEEK GF30 — 30% glass fiber reinforcement. Raises tensile strength to ~22,000 psi and compressive strength substantially. Best for structural parts that see sustained compressive loads but limited abrasion. Off-white to gray opaque.

PEEK CF30 — 30% carbon fiber reinforcement. Tensile strength to 29,000 psi, stiffness triples relative to virgin. Best stiffness-to-weight of the family. Black opaque; higher thermal conductivity than other grades. Watch for galvanic compatibility in contact with aluminum or magnesium.

PEEK ELS — Electrostatic control grade for semiconductor and cleanroom use. Surface resistivity in the static-dissipative range. Black.

PEEK 450G — Victrex's benchmark commercial grade, widely used for unfilled stock shapes; properties align closely with virgin PEEK. The 450G designation appears in many material specifications and qualification documents.

For detailed grade-by-grade comparison and selection logic, read PEEK grades and formulations.

PEEK Stock Shapes and Sizes

FedMat stocks PEEK in three primary forms:

Sheet

Available in thicknesses from 0.062" to 4.0" and standard sheet sizes of 12" × 12", 24" × 24", and 24" × 48". Tolerance on thickness: ±10% per ASTM D6262. Sheet is produced by compression molding (larger thicknesses) or extrusion (thinner gauges). Compression-molded sheet offers more consistent crystallinity through the cross-section.

Rod

Diameters from 0.25" through 12.0" in standard 4-ft and 6-ft lengths. Extruded rod has a slight crystallinity gradient from surface to core in diameters above 4"; this is normal and accounted for in standard mechanical property tables.

Tube

OD from 0.5" to 6.0", wall thicknesses to order. Tube is practical when bore tolerances matter and you want to minimize material removal. Specify ID and OD tolerances explicitly — PEEK tube holds ±0.010" on OD as extruded; tighter ID tolerances require finish machining.

Applications Overview

PEEK's five primary application domains follow directly from its property profile:

Aerospace — Structural brackets, clips, fastener components, and electrical connectors that must meet FAA FST requirements and operate at temperatures exceeding nylon or Delrin capability.

Medical — Surgical instrument handles, trial implants, sterilization tray components, and endoscopic tool bodies. PEEK's radiolucency (it is not opaque on X-ray like metals) is a significant advantage for trial implant applications.

Semiconductor — Wafer handling rings, end-effectors, etch-bath fixtures, and ion implant components. Cleanliness and chemical resistance to wet etch chemistries drive the specification.

High-Temperature Bearings and Bushings — PEEK bearings running at 200°C in petroleum pumps, compressors, and down-hole tools often outlast metal competitors while adding design flexibility.

Oil & Gas / Chemical Processing — Seal rings, valve seats, and pump components exposed to hot hydrocarbons, H₂S, and steam. PEEK withstands continuous exposure to these environments where most engineering plastics fail within weeks.

For detailed application guidance, see PEEK applications.

Machining PEEK

PEEK machines well on standard CNC mills and lathes. Unlike many filled composites, even CF30 PEEK can be machined dry with carbide tooling, though coolant is recommended above light cuts to prevent thermal distortion in thin walls. Key parameters:

• Turning: Surface speed 400–600 SFM; feed 0.003–0.008 IPR; sharp carbide or PCD insert
• Milling: 200–500 SFM; 0.002–0.005 IPT chip load; minimize tool deflection
• Drilling: Parabolic flute drills, 100–200 SFM; through-coolant preferred for deep holes
• Tapping: Use spiral flute taps; standard coatings acceptable; cutting fluid recommended

Residual stress management matters in thick PEEK stock. Pre-annealing at 150°C for 4–8 hours before final machining reduces distortion in tight-tolerance parts. Full machining guidance — including setup tips for thin-wall PEEK tubes — is in the PEEK machining guide.

Compliance and Certifications

Full compliance documentation, NSF certification status, and food-contact suitability are covered in PEEK FDA and food-grade compliance.

Specifications and Standards

PEEK stock shapes are produced to ASTM D6262, which covers requirements for polyether ether ketone sheet, rod, and tube. MIL-P-46183 covers high-performance thermoplastics including PEEK for defense applications. Dimensional tolerance conventions follow ASTM D6262 Table 1–3 by default; tighter tolerances are available to special order.

For a full listing of ASTM, NEMA, and MIL specifications applicable to PEEK, see PEEK specifications.

Cost and Sourcing

PEEK is a premium material. Virgin PEEK rod at 1" diameter runs approximately $180–$240/ft depending on quantity; CF30 grade adds a 30–50% premium. Sheet prices scale with thickness and form factor. That said, PEEK's extended service life in high-temperature and chemically aggressive environments — and its avoidance of costly secondary treatments — often justify the upfront cost.

Compared to PAI (Torlon), virgin PEEK is comparable or slightly less expensive at small quantities; GF30 and CF30 grades can exceed Torlon pricing. Against Ultem/PEI, PEEK commands a 20–40% premium for equivalent shapes.

More related guides

Cross-cluster suggestions to help shoppers and engineers explore adjacent topics:

Applications

• Bushings Bearings
• Gears
• Manifolds

Industries

• Aerospace
• Medical

Compare to other materials

• Peek Vs. Ultem Pei
• Peek Vs. Pai Torlon
• Peek Vs. Acetal Delrin

Frequently asked questions — Peek FAQ