Evonik VESTAKEEP Care M40 3DF PEEK is an unfilled medical-grade polyetheretherketone monofilament produced for fused filament fabrication. The product is manufactured from VESTAKEEP Care M40, a medium-viscosity PEEK resin, and is supplied in nominal diameters of 1.75 mm and 2.85 mm on sealed moisture-barrier spools. The 3DF designation indicates dimensional control, spooling, and documentation intended for filament-fed additive manufacturing rather than pellet extrusion. The material is specified where the additively manufactured device requires repeated steam sterilisation, dimensional stability under load above 150 °C, electrical insulation, or a well-characterised toxicological profile for tissue contact. The unfilled nature of the product distinguishes it from carbon-fibre-reinforced PEEK 3D printing grades in terms of ductility, surface abrasiveness, and melt processing behaviour.

Each spool lot is supplied with a certificate of analysis that records diameter, ovality, and residual moisture. The filament diameter is controlled to prevent under-extrusion and nozzle blockage at PEEK melt temperatures. Dimensional deviations above the specified tolerance lead to feed-roller slip and pressure fluctuation in the melt zone. The spool is packaged in a sealed aluminium-coated bag with desiccant. Once opened, the material should be printed within a controlled time window or re-dried according to the same cycle. Direct-drive extruders with hardened steel gears are recommended. Bowden configurations increase filament column load and produce skip events when print speed exceeds 40 mm/s; therefore, high-temperature direct-drive print heads are specified for this product.

Base-resin values published for VESTAKEEP Care M40 include a density of 1.30 g/cm³ per ISO 1183-1, tensile strength at break of 100 MPa per ISO 527-2, tensile modulus of 4,200 MPa per ISO 527-2, flexural strength of 170 MPa per ISO 178, and flexural modulus of 4,100 MPa per ISO 178. These values refer to injection-moulded test specimens of the base resin; the corresponding properties of FFF-printed VESTAKEEP Care M40 3DF depend on raster angle, layer time, chamber temperature, and post-annealing. Published data for fully characterised printed specimens across all raster orientations remains limited and should be generated on the target printer. The following table provides the base-resin reference properties that serve as starting values for finite-element input and design verification.

Moisture control is a decisive variable in filament-fed PEEK processing. The filament absorbs low but measurable water; residual moisture above 0.02 wt% can drive hydrolysis at melt temperature, producing internal voids, reduced molecular weight, and delamination between layers. Drying in a dry-air or vacuum oven at 150 °C for 3–5 h is required after spool exposure to ambient humidity above 60 %RH. The spool should be held in a desiccated cabinet or active dry-feed system during printing, and the unreeled filament path kept short to prevent re-uptake before the extruder. Retraction distance should be minimised below 2 mm on direct-drive systems to avoid pulling molten polymer into the cold zone and causing plugging; retraction speed is set between 10 mm/s and 20 mm/s.

Why the Available Printing Window is Narrower than Extrusion-Grade PEEK

Processing VESTAKEEP Care M40 3DF through a fused filament fabrication system requires simultaneous control of melt temperature, chamber thermal uniformity, and crystallisation. The hot end should maintain a melt zone between 400 °C and 430 °C; temperatures below this range produce incomplete interlayer fusion, while temperatures above it increase the risk of discolouration and molecular-weight loss. The glass transition of PEEK is near 143 °C per ISO 11357-2, and the melting peak is 343 °C per ISO 11357-3. A heated chamber held between 130 °C and 150 °C is required to reduce residual stress, warpage, and interlayer porosity. Build-plate temperature is typically set at 130–150 °C with a PEEK-compatible adhesive or polyimide tape. Brass nozzles are unsuitable at these temperatures; a hardened steel or ruby nozzle with a diameter of 0.4 mm or larger is recommended. Layer height is commonly 0.15–0.25 mm, and first-layer speeds are kept between 20 mm/s and 60 mm/s to allow polymer interdiffusion.

Rheologically, unfilled PEEK at 400 °C is strongly shear-thinning. Published capillary rheometry data for VESTAKEEP Care M40 3DF is limited, but the behaviour of unfilled PEEK at these temperatures supports nozzle flow at moderate speeds while increasing viscosity during slow layer changes and retractions. The medium-viscosity formulation requires higher extrusion force than high-flow PEEK grades but improves retained molecular weight after melting. This limits maximum print speed on low-torque extruders and makes a direct-drive hardened gear set necessary for consistent feeding. The extruder idler tension should be set low enough to avoid crushing the filament, because PEEK at room temperature is stiff and prone to buckling if unsupported between the spool and hot end.

On production-scale FFF systems with heated chamber volumes of 200–300 L, thermal gradients between the platen and upper build zone can exceed 10 °C. Parts placed near the chamber door may show lower crystallinity and reduced z-strength than parts placed centrally. A chamber soak time of 30 min after reaching 130 °C is used to stabilise the build environment and improve batch-to-batch dimensional repeatability. Open-frame printers are not suitable for this material because the required chamber temperature cannot be maintained, leading to warpage and interlayer failure. Published data for VESTAKEEP Care M40 3DF on specific printer platforms is limited; the values above are process-development starting points rather than universal settings.

When Unfilled Care M40 3DF Outperforms Carbon-Fibre PEEK in Additive Manufacturing

VESTAKEEP Care M40 3DF differs from general-purpose industrial PEEK 3D printing filaments primarily in the medical-grade documentation and change control attached to the VESTAKEEP Care M40 base resin. Industrial grades may be supplied with mechanical certification only, whereas the Care grade is manufactured under a medical-device quality system and accompanied by biological evaluation documentation. Compared with carbon-fibre-reinforced PEEK 3D printing filaments, the unfilled Care M40 3DF exhibits lower tensile modulus and lower heat-deflection temperature under load, but higher elongation at break and no conductive carbon particle release. In applications that require electrical insulation, repeated flexure during surgical assembly, or avoidance of carbon-particle contamination, the unfilled grade is preferred. In applications that require maximum stiffness and wear resistance, carbon-fibre PEEK is likely more suitable. The base-resin HDT/A of unfilled PEEK is typically 152 °C per ISO 75-2, whereas carbon-fibre-reinforced grades can exceed 315 °C; this gap narrows after FFF-induced porosity and crystallinity effects are considered.

Printed-part mechanical anisotropy is a further distinction. In fused filament fabrication, the z-axis strength of unfilled PEEK is commonly reported at 40–60 % of the in-plane xy strength because of incomplete reptation across the layer interface and residual microvoids. As-printed crystallinity is often below fully annealed levels; differential scanning calorimetry per ISO 11357-3 on printed specimens may show a cold-crystallisation exotherm when the chamber temperature is kept below 150 °C. Post-annealing at 200 °C for 2 h can increase crystallinity and modulus but may produce z-direction shrinkage of 0.5–1.5 %. Support structures should be removed before annealing to prevent fusion to the part surface. The product-specific magnitude of anisotropy should be validated for each build strategy and slicing parameter set.

Sterilisation-Loaded Environments and Repeated Autoclave Exposure

Steam sterilisation of VESTAKEEP Care M40 3DF devices in an autoclave at 134 °C for 18 min per ISO 17665-1 is feasible, but dimensional change is greater when the as-printed crystallinity is below the equilibrium level. Components built at low chamber temperature may undergo secondary crystallisation during the autoclave cycle, producing warpage in thin sections. Repeated autoclave exposure beyond 50 cycles has been reported for injection-moulded PEEK; published data for 3D-printed VESTAKEEP Care M40 3DF under identical cycling is limited and should be generated for each device geometry. Ethylene oxide sterilisation per ISO 11135 requires aeration to remove residues; PEEK does not impose the low-temperature constraints of some aliphatic polymers, but the device design must permit gas penetration and residue desorption. The device manufacturer is responsible for validating the full sterilisation cycle and its effect on mechanical performance.

The preceding standards matrix is a starting point for a regulatory file; it does not constitute a regulatory clearance or a claim of biocompatibility for any specific printed device. VESTAKEEP Care M40 3DF is not an off-the-shelf implantable material. Long-term implant applications require additional testing under ASTM F2026 where applicable, device-specific biological evaluation under ISO 10993-1, and compliance with ISO 13485 manufacturing controls. The printed component’s surface porosity, cleaning residues, and sterilisation residues must be characterised before clinical use.

Typical application contexts for VESTAKEEP Care M40 3DF include single-use and reusable surgical instrument components, patient-specific cutting guides, sterilisation trays, and anatomical models where repeated thermal exposure is expected. In such builds, interlayer adhesion is the primary failure mode rather than bulk resin strength. The material should not be combined with amine-based additives or highly alkaline reagents at melt temperature unless compatibility is demonstrated, because such agents can attack PEEK under prolonged thermal load. Published data for this specific configuration is limited; therefore, process validation and mechanical testing should be performed on representative prints from the actual production machine.