For general fabrication, unfilled PEEK (natural, semi-crystalline) is the default starting point: tensile strength of 90–100 MPa, continuous use temperature of 260°C, and Rockwell hardness of M94–99 place it between aluminum and acetal in machinability [S5].
PEEK was commercialized by Victrex (originally ICI) in the early 1980s; Solvay entered as a US-based producer after the original patent expired in the early 2000s, and today both Victrex 450 series and Solvay KetaSpire KT-820 series resins meet Mil-P-46183 [S3].
Unfilled PEEK: the default for chemical and thermal duty
Unfilled PEEK resists a broad range of aggressive chemistries and high-pressure steam, and it retains useful flexural modulus at high temperatures, which is why it is commonly specified for valve plates, seals, and pump components in oil-and-gas service [S1][S2].
For shop-floor machining, unfilled PEEK allows carbide tooling, surface finish of Ra 0.8–1.6 µm, and cutting speeds of 300–800 SFM, versus 120–180 SFM for reinforced grades [S5]. Pre-machining annealing at 200–250°C for 3–4 hours is required to hold tolerances down to ±0.0002" [S5].
Filled grades: when stiffness, wear, or thermal stability force a step up
Victrex PEEK 450 CA30, with 30% carbon-fiber reinforcement, is positioned as the highest-strength and highest-stiffness PEEK grade, is FDA compliant for direct food contact, meets UL 94 V-0, and survives repeated autoclave cycles [S3].
For higher-temperature downhole work, Victrex PEK HT (a polyetherketone rather than a true PEEK) retains strength at temperatures 30°C (54°F) above standard PEEK, at the cost of reduced chemical resistance and fatigue performance versus a true PEEK [S3].
Reinforced grades cut tool life by 50–70% versus unfilled PEEK, which generally forces a switch to PCD tooling for production runs [S5].
Bearing and wear grades: PTFE and graphite for dynamic service
Victrex PEEK 450 FE20 (20% PTFE powder) gives a 50% lower coefficient of friction and 25% lower wear rate than unfilled PEEK, and is FDA compliant; it is the typical pick for intermittent-service bushings and rotors where sealing at lower pressures is required [S3].
Victrex PEEK 450 FC30, a 10% graphite / 10% carbon fiber / 10% PTFE bearing grade, delivers the lowest wear and highest PV (pressure-velocity) among polyketone polymers and is specified for bushings and bearings from reusable medical devices to helicopter components [S3].
For context, PEEK in dynamic bearing and seal service can increase load capacity while operating at temperatures up to 480°F (about 249°C), an envelope that overlaps the upper end of the polymer's continuous-use window [S2].
Fabrication method: when to machine, when to mold, when to 3D print
For prototype and low-volume production (typically under 500 parts) where mold tooling is uneconomic, or where tolerances exceed ±0.005" (the typical injection-molding band), machined PEEK stock shapes are the default route, with achievable tolerances down to ±0.0002" [S5].
PEEK can also be processed by injection molding and by additive manufacturing; the high melting point permits faster feeds and speeds than most other thermoplastics on either route, and unfilled PEEK is the most machinable variant when maximum stiffness is not required [S5][S7].
For parts exposed to steam, hot water, or high-humidity environments such as food processing equipment, PEEK is a reliable choice because of its hydrolysis resistance [S8].
Decision map: which PEEK to specify for a given shop-floor job
Use unfilled PEEK when the brief is general chemical resistance, steam exposure, or a service ceiling near 260°C, and the part is not stiffness- or wear-limited; machine from stock for low volume and tight tolerance [S5][S8].
Step up to 30% carbon-filled (450 CA30 or equivalent KetaSpire) when stiffness, creep resistance, or autoclave survivability drive the spec, and accept the PCD-tooling cost [S3][S5].
Specify PTFE-bearing 450 FE20 for low-pressure sealing and moderate-wear bushings, and 10/10/10 450 FC30 when PV is the binding constraint, with FDA compliance retained for both [S3].
For temperature excursions above standard PEEK's useful envelope, look at Victrex PEK HT as a polyetherketone alternative, with the explicit understanding that chemical resistance and fatigue are reduced relative to true PEEK [S3].
Process pitfalls and shop-floor constraints
PEEK's thermal conductivity of 0.25 W/m·K is low, so heat from cutting does not dissipate like it does in metals, which forces tighter control of speeds, feeds, and fixturing to prevent warping and out-of-tolerance parts [S5].
Reinforcement fillers drive abrasiveness: glass-filled PEEK cuts tool life by 50–70% versus unfilled stock, and PCD tooling is the practical answer once a production run is committed [S5].
For medical-grade components, ISO 10993 biocompatibility is satisfied for both short- and long-term implants, but the durability of PEEK means it is generally only recommended for long-term implants rather than temporary fixation hardware [S2].
PEEK is radiolucent, so it does not muddle X-ray or CT imaging the way metal fixtures do, which is a key reason it has displaced stainless and titanium in some surgical and dental instrumentation [S2].
Across the wider engineering-plastics landscape, the same grade-and-filler logic that drives PEEK choices also drives PTFE selection for rail industry: grades, fillers, and certification map and POM Selection for General Fabrication: Grades, Specs, and Shop-Floor Criteria, which are useful reference points when PEEK is over-specified for a duty that a lower-cost polymer can meet.
Standards, suppliers, and traceability
Both Victrex 450 series and Solvay KetaSpire KT-820 series PEEK resins conform to Mil-P-46183, which is the common baseline for specifying resin pedigree in aerospace and defense drawings [S3].
Flame, smoke, and toxicity (FST) compliance for aerospace cabins is met by filled grades such as 450 CA30 and 450 FC30 at UL 94 V-0, while food-contact and medical biocompatibility are covered by FDA compliance and ISO 10993 testing, respectively [S2][S3].
For engineers cross-referencing adjacent material families, Engineering Plastic Selection for Electronics: Spec-Anchored Material Map is a useful complement because PEEK's electrical insulation and dimensional stability are part of why it appears in connector covers, transducer cases, and similar precision-device components [S2].
Watch for the next two signals: any Victrex or Solvay technical datasheet revision that re-states PV limits for 450 FC30 beyond current published values, and any 2026 update to Mil-P-46183 acceptance criteria, since both would force a re-spec on existing drawings.
For the relevant spec sheets and selection criteria, see peek, pressure transmitter, and flow meter.