🧪 PEEK
PEEK Machined Parts in Rock Hill, SC — Unfilled, Glass-Filled & Carbon-Filled PEEK Suppliers
PEEK (polyether ether ketone) sits at the top of the engineering thermoplastic hierarchy — a semi-crystalline polymer with continuous service temperatures to 250°C, tensile strength above 100 MPa, and chemical resistance that holds up in virtually every industrial solvent and hydraulic fluid environment. For Rock Hill buyers looking to replace aluminum or stainless steel in weight-sensitive housings, bearing cages, valve seats, and electrical isolation components, PEEK delivers a material that machines with precision, holds tight tolerances, and eliminates corrosion concerns entirely. The three primary grades — unfilled, glass-filled, and carbon-filled — each have a distinct performance profile that determines which application each serves.
ISO 9001ISO 13485AS9100
Unfilled PEEK: The Baseline Grade for Chemical Resistance and Biocompatibility
Unfilled PEEK (natural PEEK, undoped) is the grade specified when the application demands maximum chemical resistance, biocompatibility, or clean-room compatibility without filler particles that could contaminate process fluids or biological environments. With a tensile strength of 100 MPa, flexural modulus of 3.6 GPa, and continuous service temperature of 250°C (480°F), unfilled PEEK outperforms every commodity engineering plastic and competes favorably with aluminum for many structural applications at roughly one-sixth the density of steel.
Rock Hill's precision machining shops encounter unfilled PEEK primarily in two contexts: fluid handling components for chemical processing and semiconductor equipment (valve seats, pump impellers, fitting bodies), and biocompatible structural components for medical instruments and implantable device housings. PEEK's FDA compliance under 21 CFR 177.2415 and USP Class VI certification make it suitable for food contact, pharmaceutical, and medical device applications — a relevant capability for Carolina-region medical device manufacturers who increasingly source precision polymer components from local machine shops rather than specialty molders.
Machining unfilled PEEK requires attention to thermal management and workholding. PEEK is a poor thermal conductor, so heat concentrates at the cutting edge — recommend flood coolant or minimum quantity lubrication (MQL) to prevent thermal degradation of the workpiece surface, which appears as a brown discoloration and indicates local temperatures above 300°C. Tool geometry should emphasize sharp cutting edges and positive rake angles (15–20 degrees axial rake for end mills) to reduce cutting forces and minimize the smearing that occurs with neutral or negative rake tools. Tolerances to ±0.001 inch on machined features are achievable with proper setup; tighter work to ±0.0005 inch requires stress-relieved stock and careful fixturing since PEEK carries internal stress from the rod or plate extrusion process that can release and cause distortion after roughing cuts.
Glass-Filled PEEK: Enhanced Stiffness and Dimensional Stability for Rock Hill Industrial Components
Glass-filled PEEK (typically 30% short glass fiber by weight, designated GF30) raises the flexural modulus from 3.6 GPa to approximately 9.5 GPa and improves creep resistance significantly compared to unfilled PEEK — properties that matter when a PEEK bearing housing or structural bracket must maintain dimensional accuracy under sustained load at elevated temperature. The continuous service temperature ceiling also rises slightly to 260°C (500°F) with glass fill, and the coefficient of thermal expansion drops from 47 ppm/°C (unfilled) to approximately 20 ppm/°C, narrowing the gap with aluminum (23 ppm/°C) and improving dimensional stability in cycling thermal environments.
For Rock Hill's automotive supply chain, glass-filled PEEK appears in throttle body components, transmission valve body inserts, and under-hood sensor housings where both elevated temperature service (sustained 150–200°C) and dimensional stability under assembly torque are requirements. Automotive OEM specifications increasingly call out PEEK GF30 for these applications because it eliminates the lubrication requirements and corrosion concerns associated with aluminum while maintaining the precision dimensions needed for close-clearance valve and sensor function.
The machining characteristics of glass-filled PEEK differ from unfilled grade in one important way: the glass fibers are highly abrasive to cutting tools. Carbide tooling is required — high-speed steel wears rapidly — and PCD (polycrystalline diamond) tooling is recommended for high-volume production to maintain consistent tool life. Surface finish on glass-filled PEEK is inherently rougher than unfilled due to the fiber fracture at the cut surface; achievable Ra values are typically 63–125 Ra µin (1.6–3.2 µm) on milled or turned surfaces, compared to 32–63 Ra µin achievable on unfilled PEEK. Buyers who need smooth sealing surfaces on glass-filled PEEK components should specify surface grinding or lapping of the critical faces.
Carbon-Filled PEEK: Tribology and Conductivity for Precision Bearings and Wear Components
Carbon-filled PEEK (CF30, 30% carbon fiber by weight) is the grade specified when the application combines high load-bearing requirements with the need for inherent lubricity — bearing cages, thrust washers, seal rings, and bushing liners that run against metal counterfaces without external lubrication. Carbon fiber fill raises the flexural modulus to 17–20 GPa (approaching some aluminum alloys) and reduces the coefficient of friction against steel to 0.1–0.15 in dry sliding — a significant reduction from unfilled PEEK's 0.4–0.5 friction coefficient in the same conditions.
An additional property of carbon-filled PEEK that often surprises buyers: electrical conductivity. Carbon-fiber-filled PEEK has a surface resistivity of 10³–10⁵ Ω/sq, compared to 10¹⁶ Ω/sq for unfilled PEEK. This makes CF30 PEEK useful for electrostatic discharge (ESD) sensitive applications — wafer handling components in semiconductor equipment, electronics assembly fixtures — while also making it inappropriate for electrical isolation applications where unfilled PEEK or glass-filled PEEK is required. Rock Hill buyers specifying PEEK for electrical applications must specify the grade explicitly on the drawing and confirm the supplier understands the conductivity implications.
For Rock Hill's industrial equipment sector, carbon-filled PEEK bearing liners and wear pads on construction machinery and material handling equipment offer a compelling value proposition: longer service life than nylon or Delrin in high-PV (pressure-velocity) applications, no lubrication maintenance, and resistance to the hydraulic fluids and lubricants common in construction equipment. The PV limit for CF30 PEEK against steel is approximately 1.0 MPa·m/s (150 psi·ft/min) in dry running — substantially higher than any unfilled engineering thermoplastic. Buyers should request a PV calculation from their application engineer before committing to a dry-running bearing design to confirm the material is within its operating envelope.
Sourcing and Qualification Considerations for PEEK Components in the Rock Hill Supply Chain
PEEK stock forms — rod from 0.25 to 10-inch diameter, plate from 0.25 to 4-inch thickness, and tube — are available from specialty plastics distributors in Charlotte and Atlanta with 3–7 business day lead times for standard sizes. Bearing-grade and semiconductor-grade PEEK commands a premium and may require 2–4 week lead times. Traceability to resin lot is increasingly required for medical device and aerospace applications, and buyers should confirm their supplier can provide material certificates with resin manufacturer lot number if this is a requirement.
For medical device applications specifically, buyers should confirm that the PEEK stock is manufactured under ISO 13485 conditions and that the machining supplier has appropriate controls for biocompatible material handling — dedicated machines or verified cleaning procedures to prevent contamination from metal chips, oils, or other plastics. PEEK for implantable device components requires additional qualification per FDA 21 CFR Part 820 and any applicable device-specific standards, and the machining shop should be prepared to participate in the supplier qualification process with quality system documentation, process validation records, and first article inspection per AS9102 or equivalent.
Frequently Asked Questions
Glass-filled PEEK (GF30) is the standard choice for automotive under-hood housings that must maintain dimensional accuracy at continuous temperatures of 150–200°C and resist engine fluids including oil, ATF, and coolant. Unfilled PEEK handles the temperature and chemical resistance but is more prone to creep under sustained assembly torque — a critical factor for housing designs that use plastic bosses and fasteners to retain sensors or cover plates. GF30's flexural modulus of 9.5 GPa versus 3.6 GPa for unfilled means significantly less deflection under torque and better retention of cover seal geometry over the assembly's service life. If the housing also functions as an electrical isolator between sensors and grounded structure, confirm that GF30 meets the isolation resistance requirement — glass-filled PEEK is still an excellent insulator (surface resistivity >10¹⁵ Ω/sq), unlike carbon-filled grades. Specify the grade explicitly on the drawing as 'PEEK GF30' or by trade name reference (Victrex 450GL30, Ketron GF30) to prevent substitution of unfilled or carbon-filled grades by a cost-motivated supplier.
Yes — experienced plastic machining shops in Rock Hill and the broader Charlotte region can hold ±0.001 inch on standard machined features in PEEK with proper setup. The primary challenge is stress relief and thermal stability. PEEK rod and plate stock carries residual stress from the extrusion process, which releases after roughing cuts and causes workpiece movement — particularly in thin-wall or asymmetric sections. The solution is to rough-machine with 0.030–0.050 inch stock remaining, allow the part to stabilize for a minimum of 24 hours (some shops oven-anneal at 150°C for 2 hours), then finish-machine to final dimension. For tolerances tighter than ±0.001 inch, this stress-relief step is essentially mandatory. The second challenge is moisture absorption — PEEK absorbs approximately 0.1% water by weight in humid environments, causing dimensional change. In Rock Hill's humid Carolina climate, precision PEEK parts should be measured and shipped in sealed packaging; buyers who store PEEK stock in open bins before machining should condition the material in a dry environment before taking final measurements.
Unfilled PEEK has well-established biocompatibility credentials: it meets USP Class VI requirements, ISO 10993 biological evaluation standards, and FDA 21 CFR 177.2415 for food contact. It is widely used in spinal fusion cages, bone screws, orthopedic instrument handles, and endoscopic components. However, biocompatibility compliance is application-specific — the ISO 10993 standard requires testing in the context of the specific device contact type (blood contact, tissue contact, etc.) and duration, not just material compliance. Rock Hill machining shops supplying medical device components should operate under ISO 13485 or demonstrate equivalent quality system controls, provide material certificates with resin lot traceability, and document their machining, cleaning, and packaging processes to support the device manufacturer's biocompatibility and sterilization validation. Glass-filled and carbon-filled PEEK grades require separate biocompatibility evaluation from unfilled grades — the filler materials introduce different cytotoxicity and leaching profiles that must be independently characterized.
PEEK's density is 1.32 g/cm³ versus 2.70 g/cm³ for aluminum (6061-T6) — roughly half the weight for equivalent volume. For components where strength-to-weight ratio is optimized for plastic loads rather than metal loads, PEEK can directly replace aluminum and save 50+ percent of component weight. However, PEEK's elastic modulus (3.6 GPa unfilled) is less than 10 percent of aluminum's 69 GPa, so deflection-critical designs must be re-engineered for the lower stiffness rather than directly substituting wall thicknesses. Carbon-filled PEEK (17–20 GPa modulus) narrows the gap significantly and is more suitable for stiffness-driven substitutions. On corrosion resistance, PEEK is unambiguously superior to aluminum in nearly all chemical environments — it resists concentrated acids, strong bases, hydrocarbons, and hydraulic fluids that would attack aluminum with or without anodize. For Rock Hill industrial equipment builders specifying housings and valve bodies in chemically aggressive service, the maintenance cost elimination from removing corrosion-related repairs and replacements often justifies the material premium over aluminum within 1–2 service cycles.
PEEK withstands all common industrial sterilization methods, which is one of its primary advantages over most engineering thermoplastics in medical applications. Autoclave steam sterilization at 134°C (273°F) per EN ISO 17665: PEEK is unaffected after hundreds of cycles with no dimensional change or property degradation. Gamma radiation sterilization at standard doses (25–50 kGy): PEEK shows minimal yellowing and negligible mechanical property change, unlike many polyolefins that degrade under gamma. Ethylene oxide (EtO) sterilization: compatible, though EtO residue testing is required per ISO 11135 before use in patient-contact applications. For dimensionally critical PEEK components — gauge rings, bone trial implants, cutting guides — autoclave is the preferred sterilization method because it introduces no chemical residues and PEEK's dimensional stability at 134°C is excellent. Dimensional change after autoclave is typically less than 0.05 percent for properly annealed unfilled PEEK. Buyers receiving PEEK components for sterilizable instruments should request the machining shop's annealing documentation to confirm the stock was properly stress-relieved before final machining.
Last updated: July 2026
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