🧪 PEEK
PEEK Machining and Procurement in Rutland, VT — Unfilled, Glass-Filled, and Carbon-Filled Grades
PEEK — polyether ether ketone — earns its reputation as the gold standard of engineering polymers through a combination of properties that no other thermoplastic matches: continuous service temperature of 260 degrees Celsius, chemical resistance that includes strong acids, bases, and most organic solvents, and mechanical strength at 100 MPa tensile that competes with aluminum in specific-strength terms. In Rutland, Vermont, PEEK enters manufacturing programs through two routes — as a metal-replacement in aerospace assemblies where weight and corrosion resistance matter, and as a bearing and wear material in heavy equipment where chemical exposure would destroy conventional polymer choices. ManufacturingBase connects Vermont procurement teams with the specialized machine shops and material distributors who know the difference between unfilled, glass-filled, and carbon-filled PEEK and can document the material chain of custody that aerospace quality systems require.
AS9100ISO 9001ISO 13485
Unfilled PEEK in natural (off-white) or black form is specified when chemical purity and biocompatibility are the dominant requirements. The unfilled grade retains the full chemical resistance profile — resistance to aviation fluids, hydraulic oils, de-icing chemicals, and most solvents — without the added filler that could leach in sensitive environments. Rutland aerospace programs handling fluid system components — valve seats, manifold blocks, fitting bodies — specify unfilled PEEK because its chemical inertness prevents contamination of hydraulic or fuel circuits, and its FDA and USP Class VI compliance status means the same material spec can serve medical device programs if the company operates in that market.
Machining unfilled PEEK requires sharp carbide tooling and dry cutting or minimal lubrication — water-soluble coolants can absorb into semi-crystalline PEEK and cause dimensional change as the moisture equilibrates over time. Surface speeds of 300 to 600 surface feet per minute on a CNC lathe produce clean, burr-free surfaces; aggressive feeds that generate heat above 150 degrees Celsius begin to soften the amorphous phase and cause dimensional distortion. Tolerances of plus or minus 0.001 inch on turned diameters are routine for Rutland shops experienced with engineering polymers, and tighter tolerances require accounting for PEEK's coefficient of thermal expansion (approximately 47 parts per million per degree Celsius) when specifying inspection temperature.
Glass-Filled PEEK: Stiffness and Dimensional Stability for Structural Applications
Glass-filled PEEK (typically 30 percent short glass fiber by weight) significantly changes the material's mechanical profile: tensile strength rises to around 170 MPa from 100 MPa unfilled, flexural modulus roughly doubles to 8 GPa, and the coefficient of thermal expansion drops to approximately 20 parts per million per degree Celsius — closer to metals and critical for assemblies with aluminum or steel mating parts that must maintain fit across a temperature range. These properties make glass-filled PEEK the preferred choice for structural brackets, housings, and frames in Vermont aerospace assemblies where a metal-replacement design must hold dimensional stability across the minus 65 to 260 degree Fahrenheit service range of a typical aerospace platform.
The abrasive nature of glass fibers in the PEEK matrix shortens tool life compared to unfilled grades — carbide inserts require more frequent indexing, and solid carbide end mills may need replacement after 50 to 100 linear inches of cut depending on depth of cut and grade. Rutland shops quoting glass-filled PEEK programs should factor this into their tool cost estimates and avoid dry-cutting setups that would work for unfilled PEEK: the glass fibers generate more heat at the cutting zone, and compressed air cooling helps maintain dimensional stability in long-cycle machining runs. Surface finishes of Ra 63 microinch are straightforward; Ra 32 requires careful tool management and reduced feed rates on the final pass.
Carbon-Filled PEEK: Wear Resistance and Conductivity for Demanding Service
Carbon-filled PEEK (typically 30 percent carbon fiber by weight, or with added PTFE and graphite in wear-optimized formulations) is the bearing and tribology grade — its self-lubricating properties, enhanced compressive strength, and thermal conductivity (roughly 1 W per meter-Kelvin versus 0.25 for unfilled) make it the material of choice for thrust washers, bushings, and sliding bearing pads in heavy equipment that operates without external lubrication. Vermont quarrying equipment and heavy-machinery applications use carbon-filled PEEK bearing pads where metal-on-metal contact would be unacceptable, or where the lubricant access required for bronze or babbitt bearings cannot be maintained in a dirty field environment.
Carbon fiber's addition also makes carbon-filled PEEK electrically semi-conductive, with surface resistivity in the 10^3 to 10^6 ohm-per-square range depending on carbon loading. This is an advantage in semiconductor handling equipment (electrostatic discharge control) and a disqualifier in electrical isolation applications where unfilled PEEK's insulating properties are required. Rutland aerospace shops producing PEEK components for avionics housings must specify the grade carefully — a carbon-filled PEEK housing that was specified for weight reduction will compromise the electrical isolation of the circuit inside if the design assumed insulating properties. ManufacturingBase RFQ templates include a field for PEEK grade specification to prevent this category of substitution error.
Sourcing and Lead Times for PEEK Stock in Vermont
PEEK rod, plate, and tube stock in standard diameters (0.25 inch through 6 inch rod; 0.25 inch through 4 inch plate thickness) is available from specialty polymer distributors serving the Northeast, with typical delivery of 5 to 10 business days to Rutland for standard Victrex or equivalent grades. Custom compression-molded blanks in large cross sections (above 6 inch diameter rod or plate above 4 inch thick) require 4 to 6 week lead time from specialty molders. Semi-finished stock such as near-net-shape pads, bushings, or ring blanks can reduce machining time by 30 to 50 percent on high-volume programs and are worth specifying when annual quantities exceed 200 pieces.
Grade traceability is a sourcing requirement for aerospace programs: the material certification must identify the PEEK grade (unfilled, GF30, CF30), the manufacturer (Victrex, Solvay, or approved equivalent), lot number, and date of manufacture. Some programs specify Victrex PEEK 450G, 150CA30, or equivalent by manufacturer part number to control filler content and molecular weight precisely. Vermont procurement teams should verify that their distributor maintains lot-controlled inventory and can provide certifications before ordering — commodity distributors sometimes substitute equivalent grades without notification, which can create a non-conformance on an aerospace program if the drawing specifies a specific manufacturer grade.
Frequently Asked Questions
The three PEEK grades serve different design functions that should be matched to the application's primary load case. Unfilled PEEK (natural or black) provides the full chemical resistance and biocompatibility of the base polymer — use it when purity, electrical insulation, or medical compliance is required, and when tensile loads are modest (below 80 MPa in service). Glass-filled PEEK (GF30) adds dimensional stability and stiffness — its thermal expansion coefficient of around 20 parts per million per degree Celsius makes it compatible with aluminum and steel mating parts, and its 170 MPa tensile strength opens up structural bracket and housing applications that unfilled PEEK cannot handle. Carbon-filled PEEK (CF30 or carbon-graphite-PTFE formulations) delivers self-lubrication, high compressive strength, and semi-conductivity — it is the right choice for bearing pads, thrust washers, and sliding wear components in both aerospace and heavy equipment. The substitution error to avoid is specifying unfilled PEEK for a sliding wear application (it will wear faster than carbon-filled) or carbon-filled PEEK for an electrical isolation application (it will conduct when it should insulate). Vermont shops experienced with aerospace PEEK work ask for the application description, not just the grade, to catch these mismatches before machining begins.
PEEK's thermal expansion coefficient of 47 parts per million per degree Celsius (unfilled) means that a 6-inch PEEK rod expands approximately 0.003 inch for every 10-degree Fahrenheit temperature change — a real consideration when machining to plus or minus 0.001 inch tolerances in a shop that cycles between 60 and 80 degrees Fahrenheit. Rutland aerospace shops control this by conducting final inspection at a nominal temperature of 68 degrees Fahrenheit (20 degrees Celsius) with parts equilibrated for at least 30 minutes before measurement, documenting the inspection temperature on the dimensional report so that any temperature correction is traceable. Tool sharpness is the other critical variable: dull cutting tools generate heat that locally softens the PEEK workpiece, causing the part to spring back to a smaller diameter after the tool passes and creating undersized features on the first CMM check. Freshly indexed carbide inserts with 0- to 5-degree positive rake, minimum depth of cut (0.005 inch on final passes), and compressed air cooling produce the most consistent results. Glass-filled and carbon-filled PEEK require slightly more frequent insert changes due to the abrasive filler.
PEEK is a semi-crystalline thermoplastic that can absorb atmospheric moisture, though its moisture uptake (0.1 to 0.5 percent by weight at equilibrium) is far lower than nylon or polycarbonate. For most machining applications, PEEK does not require pre-drying — the moisture content in standard extruded or compression-molded stock is low enough that it will not affect dimensional stability or surface finish during conventional CNC machining. The exception is compression-molded PEEK that has been stored in humid conditions above 50 percent relative humidity for extended periods; for precision aerospace components where dimensional stability is critical, pre-drying at 150 degrees Celsius for 4 to 6 hours in a circulating air oven reduces moisture content to below 0.05 percent and eliminates the risk of post-machining dimensional shift from moisture equilibration. Storage of PEEK stock should be in a dry location away from direct sunlight — UV exposure does not degrade PEEK mechanically but can cause surface yellowing on natural (unfilled) grade that buyers sometimes interpret incorrectly as a quality issue. Carbon-filled PEEK is essentially UV-stable due to the carbon filler blocking UV penetration.
Yes — several Rutland-area precision machine shops operating under AS9100 revision D quality management systems produce PEEK components with the full documentation package that aerospace primes require: material certification tied to lot and manufacturer, dimensional inspection report with CMM data for all drawing-controlled dimensions, process certification for any secondary operations (cleaning, marking, packaging per the drawing requirements), and first-article inspection report for new part numbers. The AS9100 system's non-conformance process is particularly important for PEEK work because the material's cost (PEEK rod runs $50 to $200 per pound depending on grade and size) makes scrap expensive, and documented non-conformances with root-cause analysis are the mechanism that prevents recurrence. Vermont shops with both AS9100 and ITAR registration can handle PEEK components for defense programs where the housing or structural application is on a controlled assembly. ManufacturingBase allows buyers to filter supplier results by AS9100 certification status and by specific process capabilities, so procurement teams do not have to call five shops to find two that are actually qualified.
Last updated: July 2026
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