PEEK Grades — Virgin, GF30, CF30, ELS & 450G Compared

PEEK is available in five stock-shape grades that span unfilled virgin resin through heavily reinforced structural composites and specialty electrostatic formulations. Each grade targets a different engineering need, and choosing wrong costs both money and performance. This guide breaks down properties, tradeoffs, and the decision logic for selecting the right PEEK grade for your part.

At a glance:

• Virgin PEEK: maximum chemical resistance, FDA clearance, balanced properties — the default choice
• PEEK GF30: 30% glass fiber; higher compressive strength and creep resistance at cost of elongation
• PEEK CF30: 30% carbon fiber; highest stiffness and strength-to-weight; anisotropic CTE and cost premium
• PEEK ELS: electrostatic dissipative grade for semiconductor and ESD-sensitive use
• PEEK 450G: Victrex's baseline commercial grade — aligns with virgin PEEK properties, widely qualified
• Reinforced grades do not carry FDA or USP Class VI clearance without grade-specific documentation

Overview of PEEK Grade Family

All PEEK grades share the same polyether ether ketone polymer backbone. What distinguishes them is the filler (or lack of filler) compounded into the base resin before extrusion into rod, sheet, or tube. The base resin viscosity (molecular weight class) also matters: Victrex 450G has a melt viscosity index (MVI) suited for extrusion into rod and sheet; higher-MVI grades (like 90G) are used for thin-wall injection molding and not common in stock shapes.

*CF30 inherits some conductivity from carbon fiber; values vary by orientation and lot.

Virgin PEEK

Virgin PEEK is unfilled, semi-crystalline PEEK extruded or compression-molded directly from base resin without fillers or additives beyond processing stabilizers. It is the grade of choice when:

• Chemical resistance is a primary requirement (fillers can create preferential chemical attack paths)
• FDA 21 CFR 177.2415 or USP Class VI compliance is required
• Part will be machined to fine tolerances — virgin PEEK machines with the best surface finish of the family
• Impact toughness or elongation matters (30–50% elongation vs. 1–3% for reinforced grades)
• Electrical insulation performance must be maintained

Virgin PEEK's primary limitation is stiffness: at 530,000 psi tensile modulus, it deflects more under load than GF30 or CF30. For structural applications with sustained compressive loads, consider a reinforced grade.

Natural Color (Tan/Beige) vs. Black

Black virgin PEEK is compounded with carbon black for color only; this does not make it electrostatically dissipative like ELS grade. If ESD control is needed, specify PEEK ELS explicitly. Black color does offer better UV stability for any outdoor exposure.

PEEK GF30 (30% Glass Fiber)

GF30 raises tensile strength by ~50% (to 22,000 psi) and compressive strength substantially, with significantly improved creep resistance at temperature. Elongation drops from 30–50% to 2–3%, making GF30 brittle under impact.

Best for: structural brackets, pump housings, valve bodies, and load-bearing frames where compressive creep is the failure mode and CF30's cost premium isn't justified.

Watch out for: abrasive tool wear from glass fiber (carbide tooling required; shorter insert life); CTE mismatch in mixed-material assemblies (GF30 ~1.5 × 10⁻⁵ vs virgin ~2.6 × 10⁻⁵); cyclic fatigue — glass fiber can initiate cracks at stress concentrations.

PEEK CF30 (30% Carbon Fiber)

CF30 delivers the highest performance in the PEEK family: tensile strength 29,000 psi, tensile modulus 2,200 ksi, and thermal conductivity ~1.0 W/m·K (vs. 0.25 for virgin). CTE in the fiber direction drops to ~0.8 × 10⁻⁵ in/in/°F.

Best for: aerospace structural parts requiring specific stiffness, high-load bearings beyond GF30 capability, low-CTE semiconductor fixtures, robotic end-effectors.

Watch out for: galvanic corrosion against aluminum or magnesium in humid environments — isolate with glass fiber shim or film; conductivity variability (CF30 is not a controlled ESD material); highest per-pound cost in the PEEK family — verify the application before specifying.

PEEK ELS (Electrostatic Grade)

ELS (electrostatic) PEEK is formulated with a proprietary conductive additive package — not carbon black — to achieve controlled surface resistivity in the static-dissipative range: 10⁶–10⁹ Ω/sq. The mechanical properties are close to virgin PEEK (tensile strength ~14,000 psi, elongation 25–40%), and the material retains most of PEEK's chemical resistance.

ELS is specified for:

• Semiconductor wafer handling rings, carriers, and end-effectors
• Cleanroom fixtures where triboelectric charging must be controlled
• Explosive environments where static-dissipative tooling is required by safety codes
• Electronics assembly fixtures and trays

ELS does not carry FDA or USP Class VI clearance and should not be used in food-contact or implant-adjacent applications. For a comparison of ELS PEEK in semiconductor fixture use, see PEEK applications.

PEEK 450G (Victrex)

PEEK 450G is Victrex's most widely used commercial extrusion/molding grade. In stock-shape rod, sheet, and tube, 450G is functionally identical to "generic" virgin PEEK: same tensile strength (14,500 psi), same CTE (2.6 × 10⁻⁵), same FDA and USP Class VI status. The 450G designation is significant because many defense, aerospace, and medical qualification documents specifically call out "Victrex 450G" by name, making traceability to Victrex-branded resin a procurement requirement.

If your specification or customer purchase order calls for PEEK 450G by name, verify that the stock shape supplier can provide Victrex resin certificate of conformance. Generic PEEK from other resin producers (Solvay KetaSpire, Evonik VESTAKEEP) may meet the same property requirements but may not satisfy qualification documents that explicitly cite Victrex.

Grade Selection Decision Guide

1. FDA/USP compliance required → Virgin PEEK or 450G
2. ESD or static-dissipative behavior needed → PEEK ELS
3. Maximum stiffness and strength-to-weight → PEEK CF30 (check galvanic compatibility)
4. Creep resistance and compressive strength at temperature, without CF30 price → PEEK GF30
5. Spec document cites Victrex 450G by name → Source with Victrex resin documentation
6. None of the above → Default to virgin PEEK

For ASTM testing methodologies applicable to each grade, see the PEEK specifications guide.

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