🧪 PEEK
PEEK Machining and High-Performance Polymer Sourcing in Charleston, SC
PEEK (polyether ether ketone) occupies a performance tier that separates it from every commodity engineering plastic: continuous service temperature to 250°C, tensile strength exceeding 100 MPa unfilled, chemical resistance across virtually every industrial fluid, and inherent flame retardancy without additives. For Charleston's aerospace and defense manufacturers, these properties solve problems that aluminum, stainless steel, and conventional plastics each address only partially. Whether the application is a Boeing 787 structural bracket that must pass FAA FST testing, a bearing insert in a corrosive fluid handling system, or a high-temperature connector body in a naval electronics package, PEEK is increasingly the material that makes the design possible.
AS9100ISO 9001ITAR
Three PEEK Grades and Where Each Fits in Charleston's Supply Chain
Unfilled PEEK is the baseline grade — pure semicrystalline polymer with no reinforcing or conductive filler. It delivers tensile strength around 100 MPa, flexural modulus of 3.6 GPa, and continuous service temperature of 250°C. Its MRI and radar transparency, combined with USP Class VI biocompatibility, makes unfilled PEEK the choice when electrical insulation or medical-grade cleanliness is required alongside mechanical performance. Charleston aerospace shops use unfilled PEEK for bushings, washers, insulators, and fluid system seals where chemical resistance to hydraulic fluid, fuel, and de-icing fluids is essential. The FDA compliance of unfilled PEEK also appears in industrial food processing equipment — a sector present in the broader South Carolina economy.
Glass-filled PEEK (typically 30% short glass fiber by weight) raises stiffness and reduces thermal expansion while maintaining chemical resistance. Flexural modulus increases to approximately 10 GPa, and the coefficient of thermal expansion drops from 47 ppm/°C for unfilled PEEK to around 20 ppm/°C for 30% glass-filled — a critical parameter for components assembled with aluminum hardware that must maintain interference fits across a wide temperature range. The glass fill also improves creep resistance under sustained load, which matters for structural brackets and clips in airframe installations that carry constant preload from fasteners. Aerospace buyers in Charleston's 787 supply chain specify glass-filled PEEK for structural applications where dimensional stability under combined thermal and mechanical load is the design driver.
Carbon-filled PEEK (30% short carbon fiber, or 10–15% carbon fiber plus PTFE for bearing/wear applications) delivers the highest stiffness and the best wear properties of the three grades. Flexural modulus reaches 14–18 GPa, approaching aluminum in specific stiffness when weight is factored in. The carbon fiber also makes the compound electrically conductive — volume resistivity drops from >10^16 Ω·cm for unfilled PEEK to roughly 10^2–10^4 Ω·cm for 30% carbon-filled, enabling electrostatic dissipation in aircraft fuel system components and EMI shielding in defense electronics enclosures. Carbon-filled PEEK bearing grades (CF30 with PTFE and graphite) achieve PV limits exceeding 0.5 MPa·m/s dry and are used in Charleston's aerospace and defense community for self-lubricating bushings, thrust washers, and sliding pads that must operate without maintenance in hard-to-access locations.
Machining PEEK to Aerospace and Defense Tolerances
PEEK is genuinely machinable — it cuts cleanly on standard CNC turning and milling equipment, produces manageable chips, and holds tight tolerances when setup and fixturing are done correctly. The primary process consideration is thermal management: PEEK's thermal conductivity is low (0.25 W/m·K for unfilled), so heat generated at the cutting edge concentrates in the workpiece rather than conducting away. Sharp tooling, moderate cutting speeds (500–1,000 SFM for turning unfilled PEEK with PCD or sharp uncoated carbide), and compressed air cooling rather than flood coolant are the preferred approach. Flood coolant can cause thermal shock and dimensional instability in semicrystalline PEEK during machining.
Tolerance capability on PEEK depends heavily on temperature management. Unfilled PEEK at ambient temperature in a climate-controlled shop holds ±0.001 inch on turned diameters and ±0.002 inch on milled features without difficulty. Glass-filled and carbon-filled grades are more dimensionally stable due to lower CTE, and they hold similar tolerances with less sensitivity to shop temperature variation. For parts that will be measured at a specific temperature — Boeing first-article inspections are typically conducted at 68°F — parts should be allowed to equilibrate before final inspection, especially after machining generates localized heat.
Fixturing PEEK for multi-axis work requires attention to clamping force. PEEK is stiff (3.6 GPa unfilled) but not brittle, and excessive chuck or vise pressure on thin-wall features will distort the part during machining and spring back when unclamped — producing out-of-tolerance dimensions even though the cut was taken correctly. Charleston's precision polymer shops use soft jaw fixtures with generous contact area and documented torque values for repeatable setup. For delicate tubular or thin-wall PEEK features, low-melt alloy fill or wax mandrels provide internal support during machining without risk of material contamination.
FAA Flammability and Material Qualification for Aerospace Use
PEEK's inherent flame retardancy — it meets FAR 25.853 without halogenated flame retardant additives — makes it one of the few engineering polymers that clears the regulatory bar for commercial aircraft interior and structural applications without special formulation. Victrex and Solvay (the primary PEEK producers) maintain FAA-recognized material data on standard grades, and Charleston aerospace suppliers sourcing PEEK for 787 applications typically purchase from these established supply chains with full material certification traceability.
Material qualification for aerospace PEEK components goes beyond flammability. Suppliers producing parts for Boeing installation must provide material certifications tracing to the lot number and confirming compliance with the applicable material specification, whether that is a Boeing BMS spec or an industry standard. Mechanical property verification — tensile, flexural, impact — may be required on a heat-by-heat or lot basis for structural applications. Chemical resistance testing against the specific fluids the part will contact (hydraulic fluid, Skydrol, fuel, water-glycol) may be required if the application is not covered by existing qualification data.
For ITAR-controlled defense applications — PEEK components in naval electronics or classified aerospace platforms — the same material traceability applies, supplemented by access control and export compliance documentation. Charleston's defense-oriented precision machining shops maintain separate material stores for ITAR work to prevent commingling and maintain clean chain-of-custody records from material receipt through shipping.
Procurement Realities and Lead Times for PEEK Stock and Finished Parts
PEEK rod, plate, and tube in unfilled and standard filled grades is stocked by specialty plastics distributors serving the Southeast, and the Charleston area has access to same-week delivery on common sizes from regional warehouses. Standard rod diameters (0.25 inch through 4 inch) and plate thicknesses (0.25 through 2 inch) in unfilled and 30% glass-filled PEEK are the most reliably stocked. Carbon-filled grades and specialty bearing grades (CF30+PTFE+graphite) are less commonly warehoused and may require 1 to 3 week lead times from distribution.
Finished PEEK components — machined to print, inspection-verified, with material certs — have lead times driven by shop load and complexity. A simple turned bushing from unfilled PEEK can be quoted and delivered in 5 to 10 business days from a capable shop. A complex multi-feature bracket with GD&T callouts, aerospace material traceability requirements, and a first-article inspection report runs 3 to 6 weeks for initial delivery. Charleston buyers supporting active Boeing programs should build PEEK component lead times into their program schedules and maintain approved supplier lists with pre-qualified PEEK machining sources to avoid expedite situations.
ManufacturingBase profiles Charleston-area and Southeast precision polymer machining shops with capability data including maximum workpiece envelope, tolerance capability, and certifications. AS9100-certified shops are flagged for aerospace buyers, and ITAR registration is noted for defense procurement. Buyers can initiate RFQ through the platform directly to qualified suppliers, reducing sourcing cycle time versus cold-call prospecting.
Frequently Asked Questions
Glass-filled PEEK (30% short glass fiber) is the standard specification for structural brackets and clips in 787 installations where dimensional stability, sustained load performance, and thermal expansion compatibility with aluminum structure are the primary requirements. The 30% glass fill raises flexural modulus from 3.6 GPa (unfilled) to approximately 10 GPa, reduces CTE from 47 to about 20 ppm/°C, and significantly improves creep resistance under the sustained fastener preloads typical in bracket installations. Unfilled PEEK is preferred where electrical insulation or chemical purity is required alongside mechanical performance. For bearing and sliding surfaces in control system mechanisms, the carbon-fiber-PTFE-graphite filled bearing grade is the standard. Regardless of grade, parts entering Boeing's supply chain require material certification tracing to the PEEK pellet lot and confirming compliance with the applicable BMS or industry material specification — buyers should confirm with their machining supplier that this documentation will be provided at delivery.
PEEK is approximately 50% lighter than aluminum (density 1.30–1.43 g/cm³ for unfilled versus 2.70 g/cm³ for 6061-T6), and carbon-filled PEEK can approach aluminum's specific stiffness (stiffness-to-weight ratio). For components where corrosion resistance, chemical compatibility, and flame retardancy eliminate the need for surface treatment, PEEK delivers a lighter, maintenance-free alternative to aluminum brackets and clips. The tradeoff is cost: PEEK rod stock runs 10 to 30 times the material cost of equivalent aluminum, and machining time is comparable (PEEK is easier to cut but requires more careful thermal management). For high-value aerospace applications where weight savings translate directly to fuel economy over a 20-year airframe life and where corrosion resistance eliminates inspection burden, the lifecycle cost comparison often favors PEEK. Boeing's 787 program philosophy of material selection for lifecycle performance rather than unit cost is reflected in the significant PEEK content found in its structure and systems.
Yes — PEEK has exceptional chemical resistance to virtually all aviation fluids. It is compatible with Skydrol phosphate ester hydraulic fluids (which attack many polymers including nylon and acetal), Jet-A fuel, synthetic lubricating oils, de-icing fluids, and water-glycol coolants. This chemical resistance, combined with PEEK's mechanical properties at temperatures up to 250°C continuous service, makes it a preferred material for seals, valve seats, bearing bushings, and fluid system components in aircraft where exposure to multiple aggressive fluids is unavoidable. Solvay and Victrex both publish detailed chemical resistance data for their PEEK grades, and for critical fluid system applications, buyers should verify compatibility against the specific fluid formulation they are using — fluid formulations vary by manufacturer and supplier, and occasional additives in specific products can behave differently from the base fluid chemistry. Charleston shops producing 787 fluid system components can provide material compatibility documentation as part of the qualification package.
An AS9100-certified PEEK machining shop in Charleston producing parts for Boeing or other aerospace primes typically provides: a material certification tracing the PEEK lot to the polymer producer's lot number with physical and chemical properties confirmation; a first-article inspection report (FAIR per AS9102 for initial production releases) with CMM or hand gauge data for every characteristic on the drawing, actual versus nominal, with measurement method and equipment calibration status recorded; a conformance certificate (C of C) for subsequent production releases certifying the part meets all drawing requirements; and traceability markings or serialization on the part or packaging as required by the drawing or customer quality plan. For flammability-sensitive applications, the material certification should include reference to the FAA-recognized flammability data package or BMS specification compliance. Documentation packages should be retained per the customer's quality plan — typically 10 years minimum for aerospace parts.
Lead times for custom PEEK machined parts from Charleston-area precision shops vary by complexity and current capacity. Simple turned parts (bushings, washers, insulators) from unfilled or 30% glass-filled PEEK in stock sizes: 5 to 10 business days from drawing receipt to shipping. Moderately complex milled parts with multiple features and GD&T callouts: 2 to 4 weeks. Complex aerospace parts requiring first-article inspection reports, material traceability documentation, and AS9102-compliant FAIRs: 4 to 8 weeks for initial release. Repeat production orders on parts with established setups and approved first articles can typically be turned in 2 to 3 weeks. Buyers can reduce lead time by pre-qualifying suppliers, maintaining approved supplier lists, and issuing blanket purchase orders with scheduled releases rather than spot orders — this gives shops the capacity planning visibility to hold material and production slots for steady customers. ManufacturingBase can help buyers identify and pre-qualify multiple PEEK-capable Charleston suppliers to maintain supply security across their programs.
Last updated: July 2026
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