🧪 PEEK
PEEK Machining and Fabrication in Muncie, IN: Unfilled, Glass-Filled, and Carbon-Filled Grades
Polyether ether ketone (PEEK) sits at the top of the engineering thermoplastic hierarchy: continuous service to 250 degrees Celsius, chemical resistance to virtually all industrial fluids, and mechanical properties that let engineers replace metal in weight-sensitive or corrosion-exposed assemblies. Muncie's precision CNC infrastructure makes the region a capable source for machined PEEK components across automotive, industrial, and emerging medical-adjacent applications. ManufacturingBase connects procurement teams with qualified Indiana PEEK suppliers who hold tolerance, manage polymer stress relief, and certify to the grade specifications buyers require.
ISO 9001ISO 13485AS9100
Unfilled PEEK: The Foundation Grade for Muncie Precision Work
Unfilled PEEK (neat PEEK) is the baseline against which all modified grades are compared. It combines a tensile strength of approximately 14,500 psi, a flexural modulus of 560,000 psi, and continuous service temperature of 250 degrees Celsius with chemical resistance to aliphatic hydrocarbons, hydraulic fluids, and most organic solvents. In Muncie's automotive supply context, unfilled PEEK appears in fluid manifold components, bearing cage inserts, high-temperature gaskets, and under-hood electrical connector bodies where nylon and acetal fall short on temperature or chemical resistance.
Machining unfilled PEEK from extruded rod or compression-molded plate requires understanding the material's semi-crystallinity. Stock PEEK in the extruded condition has a crystallinity of approximately 30 to 35 percent; this affects dimensional stability under load and chemical resistance. Parts machined from extruded rod will have fiber-free surface finishes below Ra 0.8 micrometers with sharp carbide tooling and dry or light-mist cutting conditions. Coolant is used by some shops, but water-soluble coolants risk surface contamination that affects adhesive bonding or FDA compliance in medical-adjacent applications. Dry machining with compressed air chip clearing is the preferred approach for parts with traceability requirements.
Dimensional stability after machining is the most common failure mode in PEEK work. Residual stress from extrusion or pressing is released during machining, causing thin walls (below 0.060 inch) or complex profiles to move after completion. Best practice is to rough-machine to 0.020 inch of finish dimension, anneal at 150 to 200 degrees Celsius for two to four hours (depending on wall thickness), then finish-machine to final dimension. Skipping the anneal step is the single most common source of out-of-tolerance PEEK parts on delivery.
Glass-Filled PEEK for Higher Stiffness and Lower Creep
30 percent glass-fiber-reinforced PEEK (GF30 PEEK) raises the flexural modulus to approximately 1,300,000 psi -- more than double the unfilled grade -- while increasing compressive strength and reducing creep under sustained load. These properties make GF30 PEEK the preferred choice for structural brackets, valve bodies, and load-bearing bushings in the automotive and industrial markets where dimensional stability under sustained stress is required. The trade-off is tribological: glass fibers are abrasive to mating surfaces, making GF30 unsuitable for bearing applications against soft metal shafts unless a sacrificial liner is used.
Machining glass-filled PEEK demands attention to tooling wear. The glass fibers (10 to 20 micrometers diameter) accelerate edge wear on carbide tools at roughly three to four times the rate observed with unfilled PEEK. PCD (polycrystalline diamond) tooling extends tool life significantly and is the right investment for production quantities above 50 pieces. For prototype and short-run work, uncoated carbide grade C2 with a fresh cutting edge and cutting speeds of 400 to 600 surface feet per minute is workable, with tool inspection every 10 to 15 parts. Hole quality in GF30 PEEK requires sharp drills and low feed rates (0.003 inch per revolution for holes under 0.25 inch) to avoid delamination at exit.
Surface finish on GF30 PEEK will be coarser than unfilled PEEK due to fiber pullout: Ra 1.6 to 3.2 micrometers is typical on milled surfaces rather than the sub-Ra-0.8 achievable with unfilled. Buyers specifying sealing or bearing surfaces in GF30 PEEK should confirm that the achievable surface finish is compatible with the mating component design before committing to the grade.
Carbon-Filled PEEK for Bearing and Wear Applications
Carbon-fiber-reinforced PEEK (CF30 PEEK) is the tribologically superior choice for bearing, bushing, and wear-surface applications in the Muncie market. The carbon fiber reinforcement raises stiffness to approximately 2,200,000 psi flexural modulus and adds lubricity that reduces the coefficient of friction against steel from approximately 0.35 for unfilled PEEK to 0.15 to 0.20 for CF30. This makes CF30 PEEK the material of choice for thrust washers, wear pads, and rotating seals in automotive transmissions, pumps, and hydraulic systems where PV values (pressure times velocity) exceed the capacity of PTFE-based bearings.
In Muncie's automotive drivetrain supply context, CF30 PEEK has displaced bronze and aluminum bronze bushings in several fluid-lubricated bearing applications where corrosion resistance, reduced maintenance, and weight savings justify the polymer premium. The key application parameter is PV limit: CF30 PEEK in a dry-running condition typically carries a PV limit of 4,000 to 6,000 psi-ft/min; in oil-lubricated service, PV limits above 15,000 psi-ft/min are achievable. These parameters should be confirmed with the material supplier's application data rather than assumed from general-purpose bearing calculations.
Carbon-filled PEEK is electrically conductive due to the carbon fiber network, with surface resistivity in the range of 100 to 10,000 ohms per square depending on fill level and fiber distribution. This makes CF30 PEEK suitable for electrostatic discharge (ESD) protection applications in semiconductor and electronics manufacturing but disqualifies it for use as an electrical insulator. Procurement teams specifying CF30 PEEK for electrical isolation purposes must switch to unfilled or glass-filled grades; confirm the application requirement before committing to grade.
Frequently Asked Questions
PEEK stock (extruded rod or compression-molded plate) contains residual stress from the manufacturing process. When material is removed during machining, the stress distribution changes and the remaining material redistributes into a new equilibrium shape. This movement is most pronounced on thin walls below 0.060 inch, deep pockets, and asymmetric cross-sections where the original stock geometry was heavily modified. The standard prevention method is a roughing-annealing-finishing sequence: rough machine to 0.015 to 0.025 inch of finish dimension, anneal the part at 175 degrees Celsius for one hour per 0.25 inch of wall thickness (minimum two hours), then finish-machine to final tolerance. The anneal step relieves the stress introduced by both the original extrusion and the roughing operation, leaving a stable blank for final cuts. Some shops skip annealing on simple turned parts with uniform walls and achieve acceptable results, but complex prismatic parts with varying wall thickness almost always require the intermediate anneal to hold position tolerances below plus or minus 0.003 inch.
For an automotive pump bushing operating in a lubricated environment, CF30 PEEK is the correct choice in virtually all cases. The carbon fiber reinforcement provides a coefficient of friction against steel of approximately 0.15 to 0.20 in boundary-lubricated conditions, compared to approximately 0.35 for unfilled PEEK, significantly extending bushing service life and reducing shaft wear. CF30 PEEK also has higher compressive strength and better creep resistance under sustained radial load, which matters for a bushing carrying pump shaft loads. Unfilled PEEK is preferred only when electrical isolation is required (CF30 is conductive), when the bearing geometry is too thin for carbon fiber reinforcement to be effective (below approximately 0.060 inch wall), or when the mating shaft is a soft material like aluminum or titanium that would be abraded by the carbon fibers. In a steel shaft application with engine oil lubrication, CF30 PEEK in a press-fit or retaining-ring-retained bushing is the standard engineering recommendation.
Muncie CNC turning shops routinely hold plus or minus 0.001 inch on outside diameters and bore diameters in unfilled PEEK for production quantities with proper process controls including material annealing and temperature-controlled inspection. For single-point turned outside diameters above 0.5 inch, plus or minus 0.0005 inch is achievable with sharp tooling, light final cuts of 0.003 to 0.005 inch depth, and dimensional measurement after thermal equilibration to 68 degrees Fahrenheit. Glass-filled and carbon-filled grades hold slightly looser tolerances due to fiber-induced surface variation: plus or minus 0.001 to 0.002 inch is typical on reinforced grades. For fits requiring interference or close clearances such as bearing bores in the H7/p6 or H7/f7 ISO fit range, a test bore in scrap material is recommended before committing the production run, as PEEK's thermal expansion coefficient (47 to 54 ppm per degree Celsius for unfilled) means that a bore measured at room temperature will be slightly different in diameter at the service temperature of the application.
PEEK is substantially less moisture-sensitive than nylon or polycarbonate and does not require pre-drying before machining under normal shop conditions. However, stock stored in high-humidity environments above 80 percent relative humidity for extended periods can absorb trace moisture that causes slightly elevated surface roughness on finish cuts. Standard shop storage at 50 to 60 percent relative humidity is adequate. For medical-grade PEEK intended for implantable or sterile applications, stock should be stored in sealed original packaging until cutting to prevent contamination, and machined parts should be cleaned per the applicable medical cleaning protocol before dimensional inspection and packaging. PEEK does not UV-degrade under normal shop fluorescent lighting, so no special light shielding is required during storage or processing.
For PEEK work approaching ISO 13485 or FDA-regulated applications, the supplier evaluation checklist should cover: quality system certification (ISO 13485 preferred, ISO 9001 acceptable with documented medical-specific procedures), material traceability documentation from resin lot through finished part, a documented annealing and inspection process specific to PEEK, calibrated CMM with PEEK-appropriate contact force settings, and packaging that prevents contamination from metallic chips, cutting fluids, or particulate. Ask specifically whether the shop segregates PEEK machining from metallic parts machining or at minimum has a documented procedure for preventing cross-contamination of polymer surfaces. Request a sample first-article inspection report from a prior PEEK job to verify that the shop generates dimensional data in the format required by your quality system. ManufacturingBase RFQ submissions allow buyers to filter for ISO 13485-certified suppliers in the East-Central Indiana region and attach traceability requirements to the initial request, reducing qualification time compared to an open web search.
Last updated: July 2026
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