Ensinger TECAFIL PEKK natural - 1,75 mm - Filament Polyetherketoneketone

When TECAFIL PEKK natural is specified for aircraft interior air distribution components, the 1.75 mm filament is introduced into the FFF toolpath as a 100 wt% unfilled polyetherketoneketone feedstock; no flame-retardant powder, no glass fibre, and no carrier resin are added because the base polymer’s aromatic ketone structure provides resistance to ignition and char formation when tested under FAR 25.853(a) Appendix F Part I vertical burn conditions of 60 s exposure. Printed coupon geometry is prepared with 100 % rectilinear infill and annealed before flame testing; measured burn length is compared against the 152 mm limit and afterflame time against the 15 s limit. Tensile properties are determined on Type V specimens machined from printed plaques using ASTM D638-14, flexural modulus is measured on 3.2 mm printed bars under ASTM D790-17, and heat distortion temperature is evaluated at 1.82 MPa loading according to ASTM D648-16. The downstream production sequence begins with drying the filament at 120 °C for 4 h until moisture content is below 0.02 %; printing is performed on a direct-drive high-temperature FFF system with a hardened steel nozzle, with the nozzle setpoint held between 345 °C and 375 °C, the bed at 130–150 °C, and the build chamber at 170–200 °C. Layer height is set to 0.15 mm, wall line count is increased to reduce through-wall porosity, and toolpath overlap is adjusted to compensate for the high melt viscosity of unfilled PEKK at deposition shear rates below 100 s⁻¹. After build completion, components are annealed at 200 °C for 2 h under nitrogen, then machined with carbide end mills to produce final hole-to-edge tolerances of ±0.05 mm. Terminal finished article types include environmental control system duct segments, air distribution sleeves, wire harness stand-offs, cabin sensor brackets, and proximity switch housings. Published data for printed PEKK in primary structural load paths is limited; the material is therefore constrained to non-structural interior and equipment-support functions unless additional qualification is performed.

How Does Annealing After Printing Affect the Biocompatibility Evaluation of Patient-Specific PEKK Guides?

With the 1.75 mm TECAFIL PEKK natural filament used at 100 wt% unfilled feedstock, patient-specific surgical guides are produced by FFF followed by stress-relief annealing; the annealing step is critical because residual interlayer stress can alter surface energy and leachable species content, both of which are assessed under ISO 10993-1:2018. Cytotoxicity testing is performed per ISO 10993-5:2009 using extracts prepared after 72 h immersion in cell culture medium at 37 °C; sensitisation potential is evaluated per ISO 10993-10:2010; and endotoxin limits are controlled through depyrogenation procedures referenced in the device master validation plan. The natural unfilled grade contains no radiopaque filler, so CT visibility relies on shape contrast rather than material density; published data for long-term implantable PEKK devices manufactured by fused filament fabrication is limited, and this application is limited to single-use surface contact or temporary intraoperative positioning. The downstream printing process uses nozzle setpoints between 345 °C and 370 °C, a chamber maintained at 180–200 °C, and a bed temperature of 140–150 °C. Critical drill-guide sleeves are built with 100 % infill and 0.12 mm layer height to reduce interlayer discontinuities at cannulated tool paths. Mechanical supports are removed by hand finishing; the part is then annealed at 180–200 °C for 2 h in air to relax residual stress without exceeding the material’s cold-crystallisation limit. Cleaning is performed by ultrasonic washing in isopropyl alcohol followed by steam autoclave at 121 °C for 15 min; the absence of moisture absorption is confirmed gravimetrically before packaging. Terminal finished article types include maxillary and mandibular cutting guides, custom drill orientation blocks, surgical saw capture jigs, and pre-surgical anatomical models.

Downhole Seal Backup Rings and Compressive Creep at 150 °C

TECAFIL PEKK natural is used at 100 wt% in FFF-produced non-metallic seal components for oil and gas downhole tools; the feedstock is not blended with PTFE or graphite because PEKK itself provides the required extrusion resistance in high-pressure packing stacks and avoids particle-filled interfaces that act as leak paths. Materials selection is qualified under ISO 23936-1:2009 for thermoplastics in sour hydrocarbon service, with supplementary non-metallic seal validation per NORSOK M-710. Compressive yield and creep behaviour are evaluated using ASTM D695-15 at 23 °C and 150 °C; flexural modulus is measured according to ISO 178:2019 on machined printed coupons. The addition fraction remains 100 wt% PEKK; no filler is introduced because particulate additives reduce melt-chain interdiffusion and create microvoids at layer interfaces, which lowers the threshold for extrusion damage under cyclic downhole pressure. The filament is dried at 150 °C for 4 h, printed at nozzle setpoints of 350–375 °C, chamber temperature 200–220 °C, and bed temperature 150–160 °C. Layer height is controlled at 0.12 mm, infill at 98 % with contour-parallel toolpaths, and nozzle retraction is minimised to avoid starved seams in thick ring sections. After printing, components are annealed at 220 °C for 4 h to increase crystallinity and shift the glass transition toward the upper end of the 155–165 °C range. Final outer and inner diameters are machined to ±0.02 mm, and sealing faces are lapped to a surface finish below 0.8 µm Ra. Terminal parts include anti-extrusion backup rings, coil tubing wear pads, downhole electrical isolator discs, and annular safety valve seat inserts. These components are not rated as pressure-retaining metallic replacements and must be used only in non-metallic static sealing or isolation functions.

Custom pump wear components and instrument housings in chlor-alkali and hydrometallurgical plants are printed from TECAFIL PEKK natural at 100 wt% feedstock fraction; glass-filled grades are explicitly avoided because glass fibres degrade acid resistance at the fibre-matrix interface under hot hydrochloric acid service. Chemical resistance is checked per ASTM D543-14 immersion in reagent concentrations representative of the process stream, and environmental stress cracking resistance is evaluated using ISO 22088-3:2006 bent strip strain of 0.5 % in process fluids at 80 °C. Flexural strength is determined using ISO 178:2019 on printed coupons machined from 6 mm thick blocks. The 1.75 mm filament is dried at 120 °C for 4 h to below 0.02 % moisture; printing uses a hardened nozzle at 345–365 °C, bed 130–150 °C, chamber 170–200 °C, layer height 0.2 mm, and 100 % infill for pressure boundaries. After build, parts are annealed at 200 °C for 2 h, then post-machined with polycrystalline diamond tooling to maintain flatness and seal-face roughness below 0.8 µm Ra. Terminal articles include centrifugal pump wear rings, impeller housing inserts, level transmitter sensor guards, dip tube spacers, and valve stem packing followers.

When Polyetherketoneketone Replaces Mica and Aluminium in Battery Cell Spacer Plates

At 100 wt% TECAFIL PEKK natural, FFF is used to produce electrical insulation and creep-resistant spacer plates for low-volume electric vehicle battery prototypes; the unfilled grade is selected because mica-filled laminates cannot be formed into integrated edge features without secondary routing, and aluminium requires anodising to prevent galvanic contact with cell housings. Flammability is classified by UL 94 V-0 at 0.75 mm thickness on printed test coupons; relative thermal index is assessed under UL 746B at electrical and mechanical endurance temperatures not exceeding 140 °C; dielectric strength is measured using ASTM D149-20 on 1.0 mm specimens; and surface resistivity is measured per ASTM D257-14 to confirm insulation behaviour. Published FFF-specific RTI values for this exact natural-grade filament are limited, so printed part qualifications should be run against the specific cell stack temperature profile rather than relying solely on injection-moulded PEKK data. The filament is pre-dried at 120 °C for 4 h; printing is performed on a high-temperature bed at 150 °C with chamber at 200 °C, layer height 0.15 mm, and 100 % infill. After printing, plates are levelled by face milling to flatness 0.05 mm, and mounting holes are reamed to H7 tolerances. Terminal articles include cell-to-cell compression spacers, busbar isolation rails, thermocouple retention blocks, and module end-plate insulation sheets. Natural PEKK is not inherently intumescent and must not be substituted for thermal runaway barrier materials in the cell stack.

Wafer handling fixtures with low outgassing and electrostatic decay targets

Within semiconductor backend manufacturing, TECAFIL PEKK natural at 100 wt% is employed for wafer handling fixtures where outgassing, particle generation, and dimensional stability must be balanced against the insulative nature of the unfilled polymer. Outgassing is tested under ASTM E595-15 with total mass loss below 0.5 % and collected volatile condensable material below 0.1 %; chemical compatibility with common process chemicals is rated according to SEMI F57-0601; and electrostatic decay is measured using Federal Standard 101C Method 4046, though the natural unfilled grade typically remains insulative at surface resistivity above 1 × 10¹³ Ω/sq and therefore requires external grounding for static-sensitive reticle handling. The 1.75 mm filament is dried at 120 °C for 4 h and printed on a high-temperature FFF platform at nozzle 345–370 °C, chamber 180–200 °C, bed 140–150 °C, layer height 0.12 mm, and 100 % infill. After printing, surfaces are fly-cut or lapped to flatness 0.02 mm, and edge radii are generated by CNC to prevent particle entrapment. Terminal articles include reticle storage cassette shelves, wafer sorting combs, mask frame spacers, and end-effector tips for atmospheric robotic handling.

Filament dimensional conformance and incoming inspection

For a 1.75 mm feedstock, diameter drift outside ±0.05 mm changes feed rate and can generate melt-pressure fluctuation at the nozzle. Incoming inspection on direct-drive extruders with hardened steel feed zones should measure the strand with a two-axis laser micrometer at intervals no wider than 500 mm across the first 5 m of a new spool. A maximum ovality of 0.03 mm is used as a practical acceptance limit; above that threshold, the filament may alternately slip and overfeed in the drive gear. The diameter value is measured at 23 °C and 50 % relative humidity after the spool has equilibrated to avoid transient dimensional variation from moisture expansion.

Spool-to-spool variation in melt volume-flow rate is more difficult to detect visually. Resin lot drift can be screened by melt volume-flow rate testing under ISO 1133-1:2022 at 380 °C with a 5 kg load; a large viscosity shift changes die swell, strand width, and the extrusion multiplier required to produce a void-free raster. Batch-to-batch variation in 1.75 mm filament is therefore controlled by both dimensional metrology and rheological lot checks.

Moisture content is quantified by Karl Fischer coulometric titration according to ISO 15512. Unfilled PEKK reaches an equilibrium moisture uptake near 0.20 % by mass at 23 °C and 50 % relative humidity when tested under ISO 62. A residual moisture level above 0.04 % at the feed inlet will decompose into steam during extrusion, producing intra-raster porosity and audible outgassing at the nozzle.

Because residual moisture in polyetherketoneketone behaves as a volatilisation source at melt temperature, drying before extrusion is mandatory. The filament is dried in a convection dryer at 120 °C to 150 °C for 3–4 h; the drying air should have a dew point below −20 °C. After drying, the spool should be fed from a purged dry box or sealed holder with desiccant. At 150 °C drying, extended exposure beyond 6 h can cause strand embrittlement and surface discolouration, so timer-controlled cycles are preferred over indefinite standby. The dryer volume should allow at least one spool per 0.2 m³ to maintain uniform heat transfer; stacked spools in a static oven develop temperature gradients that leave the core material wet while the outer windings are over-dried.

During extrusion, the first observable consequence of incomplete drying is micro-void formation in the top rasters. In sectioned polished cross-sections evaluated under optical microscopy at 50× to 200×, steam-induced voids appear as spherical pores with diameters from 10 μm to 80 μm. These pores act as crack initiation sites in tensile testing under ISO 527-2 and reduce the apparent interlaminar toughness in mode-I fracture tests.

Interlayer strength in unfilled PEKK is bounded by melt diffusion and surface reactivation. At a nozzle temperature of 355 °C, the melt viscosity remains high enough to prevent neat filling of sharp corners unless the extrusion multiplier is increased by 3–5 % relative to standard amorphous filaments. Layer adhesion is improved when the previous layer remains above the material cold crystallisation temperature; this is why chamber or bed heating is required for structural parts. Data from instrumented tensile pull-off coupons printed in the z-orientation and tested under ISO 527-2 show a more consistent failure at rasters when the chamber is held above 90 °C, but published data for this specific configuration is limited.

What separates PEKK from PEEK and PEI in high-temperature service?

The primary difference in backbone chemistry is the ratio of ketone to ether linkages. PEKK has a higher ketone density, which raises the glass transition temperature but suppresses the crystallization rate relative to PEEK. This combination has processing implications: parts can be deposited with lower accumulated residual stress, but as-printed mechanical properties remain less stable until post-crystallization is completed. The comparison in Table 1 is based on typical published unfilled-grade data and is not a batch-specific certificate of conformance.

Property	Method	PEKK natural	PEEK unfilled	PEI unfilled
Glass transition	ISO 11357-2	155–162 °C	143–150 °C	215–217 °C
Melting temperature	ISO 11357-3	305–335 °C	340–345 °C	none
Tensile modulus	ISO 527-2	3.2–3.5 GPa	3.6–4.0 GPa	3.0–3.3 GPa
Tensile strength at yield	ISO 527-2	90–100 MPa	95–110 MPa	85–100 MPa
Heat deflection temperature at 1.8 MPa	ISO 75-2	160–180 °C	150–170 °C	190–200 °C

Property

Method

PEKK natural

PEEK unfilled

PEI unfilled

Glass transition

ISO 11357-2

155–162 °C

143–150 °C

215–217 °C

Melting temperature

ISO 11357-3

305–335 °C

340–345 °C

none

Tensile modulus

ISO 527-2

3.2–3.5 GPa

3.6–4.0 GPa

3.0–3.3 GPa

Tensile strength at yield

ISO 527-2

90–100 MPa

95–110 MPa

85–100 MPa

Heat deflection temperature at 1.8 MPa

ISO 75-2

160–180 °C

150–170 °C

190–200 °C

PEI exhibits a higher heat deflection temperature but its amorphous structure is more vulnerable to environmental stress cracking in chlorinated solvents and polar cleaning fluids. PEKK and PEEK both develop semicrystalline lamellae after annealing; their chemical resistance in hydrocarbon and acidic media is generally governed by the degree of crystallinity rather than by short-term thermal resistance alone. The lower melting peak of PEKK permits processing at similar or slightly reduced nozzle settings compared with PEEK, but the thermal window above the melt peak remains narrow.

For a component that must survive hot-wet conditions, PEKK is often selected over PEEK when lower crystallisation speed reduces warp in thick sections and when the application demands consistent compressive performance at 150 °C to 180 °C. PEI is selected for electrical or low-stress thermal applications where processing ease outweighs solvent resistance; PEI cannot be annealed into a semicrystalline state and therefore remains dimensionally stable but susceptible to stress-cracking agents. Compared with polyphenylsulfone and polyethersulfone, unfilled PEKK provides higher tensile modulus and better resistance to hot aliphatic hydrocarbons, but fewer amorphous-processing accommodations such as low-temperature nozzle and bed settings.

When a heated chamber is unavailable

The product is not restricted to heated-chamber machines, but the process boundary shifts. Supplier guidance for unfilled PEKK filament recommends a heated build chamber at 80 °C to 120 °C for sections exceeding 6 mm in thickness. When no chamber heater is present, the bed is maintained at 120 °C to 150 °C and the nozzle temperature is kept at the upper end of the 355–375 °C range to reduce melt viscosity and extend the interlayer wetting time. Below 60 °C chamber equivalent temperature, z-direction tensile strength typically falls below 35 MPa and delamination may occur at raster-to-raster stress concentrations during cool-down.

Open-build configurations require the print to be shielded from forced convection cooling; a peripheral skirt with a minimum height of 10 mm directs heat from the bed upward and reduces vertical thermal gradient. Build speeds above 40 mm/s in such configurations are associated with intermittent adhesion loss in corner radii, particularly when extrusion temperature is below 365 °C. In direct-drive extruders operating near 375 °C, dwell time in the transition zone should be kept below 2 min to limit chain scission. Purge with unfilled purge polymer or PEKK scrap after each print reduces carbonized residue at the nozzle tip. A hermetic hopper or dry feed path is used to avoid moisture regain during prints exceeding 8 h.

Chemical compatibility of unfilled PEKK is most relevant to applications that combine elevated temperature with hydrocarbon exposure. In oilfield equipment screening under ISO 23936-1:2022, PAEK semicrystalline materials are preferred over amorphous sulfone polymers for resistance to hot brine, hydrogen sulfide, and aliphatic hydrocarbons; however, this product should not be specified for continuous immersion in concentrated sulfuric acid, fuming nitric acid, or methylene chloride. Steam sterilisation of printed components at 134 °C and 2.1 bar is possible if the part is annealed to stabilise crystallinity; validation is performed under ISO 17665-1 on the finished geometry because internal voids and freeze-off defects alter moisture conduction.

Annealing after deposition is used to increase crystallinity and reduce residual stress. Typical post-print annealing for unfilled PEKK is conducted at 180 °C to 200 °C for 2 h, followed by slow cooling at 0.5 °C/min to below 100 °C. This step is mandatory when the intended service temperature exceeds 120 °C, because unannealed parts may continue crystallizing and induce geometric distortion during the first thermal excursion. The operational boundary is defined by the filament 1.75 mm geometry: standard 0.4 mm brass nozzles are not suitable for the required processing temperature; hardened steel or nickel-plated copper alloy nozzles with a nominal orifice of 0.4–0.6 mm are used to limit catalytic degradation from brass.

In high-temperature tooling and aerospace ducting applications, the product is qualified against part-specific performance standards rather than generic polymer datasheet values. Flammability, smoke, and toxicity screening may be required under 14 CFR 25.853 or sector-specific equivalents; published data for this specific configuration is limited, so each printed geometry must be verified on the final build orientation and thickness. The product should not be combined with additives or support materials containing amine-based surfactants that can accelerate stress-cracking in finished parts.

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