BASF 3D Ultrafuse PA6 GF30 is a short-glass-fibre-reinforced polyamide 6 feedstock for fused filament fabrication. The grade designation identifies 30% by weight chopped glass fibre in a polyamide 6 matrix; the term “Conditioned” refers to the moisture-equilibrated state after exposure to 23 °C and 50% relative humidity until mass stabilisation in accordance with ISO 1110. Conditioning is a bulk water absorption process, not a surface coating, and it plasticises the polyamide 6 by disrupting interchain hydrogen bonding. The filament is supplied in 1.75 mm and 2.85 mm nominal diameters, and the glass-fibre loading increases density relative to unfilled polyamide 6 while raising stiffness, creep resistance, and heat deflection temperature. Published dry-state datasheet values include a density of approximately 1.28 g/cm³ when tested to ISO 1183-1, a tensile strength of 105 MPa in the XY build orientation when tested to ISO 527-2, and a tensile modulus of approximately 6,200 MPa in the same orientation. These values are orientation-dependent and should not be used as isotropic design allowables.

Because the glass fibres are short and dispersed by melt compounding, printed parts develop a layered microstructure in which fibres align preferentially along the deposition path. A printed tensile bar with 100% rectilinear infill and 0.2 mm layer height can show XY-plane modulus approaching the fibre-dominated upper bound, while the Z-axis tensile strength may remain 40–60% of the XY value, depending on nozzle temperature, raster angle, and build-chamber temperature. Conditioning reduces the stiffness difference only partially because water plasticises the matrix but does not reorient the glass fibres. Injection-moulded PA6 GF30 data are therefore not directly transferable to printed part design without orientation-specific testing.

How Does Moisture Conditioning Alter the Failure Mode of PA6 GF30?

Water uptake in PA6 GF30 occurs predominantly by diffusion through the amorphous regions of the polyamide, and the equilibrium moisture content at 23 °C and 50% relative humidity is typically in the range 1.5–2.5 wt%. The absorbed water lowers the dry glass transition temperature of approximately 60 °C to below 20 °C in the saturated state, changing the room-temperature failure mechanism from a relatively low-elongation fracture to a more ductile yield-dominated response. Dry-conditioned parts can therefore exhibit higher impact energy absorption after conditioning, but the tensile modulus and creep resistance are reduced. This shift is particularly important in snap-fit geometries and press-fit inserts: a geometry designed for dry PA6 GF30 may survive assembly after conditioning because the matrix yields locally, while a conditioned part subjected to high sustained load may creep more than dry-state datasheet values suggest. The table below compares the dry printed state with the expected conditioned response at 23 °C and 50% relative humidity; the conditioned values are ranges drawn from published supplier information and are not design allowables.

Conditioning of printed parts can be accelerated by immersion in 40 °C water for 2–8 h, but rapid water uptake creates a moisture gradient and may produce transient tensile surface stresses. Equilibrium conditioning in air at 23 °C and 50% relative humidity is preferred when dimensional and mechanical stability are being assessed. The time to equilibrium depends on wall thickness and raster density; a 3 mm solid section may require several days to reach plateau mass.

Drying, Nozzle, and Bed Parameters for Fibre-Loaded Polyamide 6 Extrusion

Drying is the controlling step before processing PA6 GF30. The filament should be dried at 80 °C for 4–12 h in a desiccant or circulating-air dryer with a dew point below -40 °C. At ambient relative humidity above 60%, unsealed spools should be re-dried before printing because absorbed moisture above 0.1% by weight causes steam voids, filament popping, and reduced interlayer fusion. The presence of 30% glass fibre raises melt viscosity and creates a shear-thinning response; the filament is therefore more demanding on the extrusion system than unfilled PA6. A hardened steel, tungsten carbide, or other abrasion-resistant nozzle is required because glass fibre accelerates bore wear in brass. A nozzle diameter of 0.4 mm to 0.6 mm is preferred, with 0.4 mm being the minimum practical diameter for reliable flow. Representative starting parameters are a nozzle temperature of 260 °C to 280 °C, a bed temperature of 80 °C to 100 °C, and a print speed of 30–60 mm/s on direct-drive extrusion systems. Higher fibre loading increases the risk of nozzle accumulation at low shear rates, so prolonged idle periods at temperature should be avoided. The build-chamber temperature is preferably maintained at 60 °C to 80 °C for sections thicker than 10 mm to slow cooling and reduce interlayer stress. Lower chamber temperatures do not prevent printing but reduce Z-direction strength and increase the probability of mid-part delamination in large flat geometries.

Thermal Deformation and Fibre-Induced Residual Stress in Unheated Build Chambers

Glass fibre lowers the coefficient of linear thermal expansion of PA6 GF30 relative to unfilled PA6, which reduces but does not eliminate warpage. Published values for glass-reinforced polyamide 6 place the coefficient of linear thermal expansion in the flow direction at approximately 40–60×10⁻⁶ K⁻¹, compared with 110×10⁻⁶ K⁻¹ for unfilled PA6. However, the printed bead itself introduces residual stress because the deposited fibre-filled melt cools and shrinks at a different rate than the underlying layer. In unheated or low-temperature build chambers, this residual stress can produce visible corner lifting on flat rectangular parts even when the bed adhesion is sufficient. The effect is largest in the first 5–10 layers and in sections with high per-pass bead length. Heated chambers, controlled cooling, and adhesion promoted by polyamide-specific bed treatments are therefore more important for PA6 GF30 than for unfilled PA6 despite the lower thermal expansion coefficient. Stress relief annealing is not universally required; if used, it should be performed below the melt temperature and after the part is removed from the bed to avoid geometry distortion.

The grade is used for assembly jigs, robotic gripper fingers, dimensional inspection fixtures, and low-volume functional housings where the material’s higher stiffness and heat deflection temperature provide a measurable advantage over unfilled PA6. Heat deflection temperature B under 0.45 MPa is reported at approximately 200 °C when tested according to ISO 75-2/B; however, continuous use at that temperature is not recommended because oxidative degradation and creep accelerate. For parts exposed to ambient moisture, design calculations should use conditioned-state properties rather than dry-state values. In fatigue-sensitive or impact-critical applications, qualification testing on printed specimens is necessary because published fatigue data for fused filament fabricated PA6 GF30 is limited. The fibre-matrix interface, void fraction, and raster boundary separation are the most common initiators of mechanical failure in printed parts made from this grade.

When the Glass-Filled Grade Replaces Unfilled PA6 in Functional Tooling

Substitution of unfilled PA6 with PA6 GF30 in existing tooling designs is not a direct material swap. The glass-filled grade has a much higher elastic modulus, but its dry-state elongation at break is lower, so snap-fit geometries and living hinges designed for unfilled nylon may fracture during assembly unless the part is conditioned. Compared with unfilled PA6, the glass-filled product also exhibits lower moisture uptake, typically 1.5–2.5 wt% at 50% relative humidity, and improved dimensional stability in humid or temperature-fluctuating environments. Against PA6 CF grades, the glass-filled product is generally lower in cost and electrically insulating, but its specific stiffness is lower because glass has a lower modulus-to-density ratio than carbon fibre. Against PA12 GF, the PA6-based product offers higher stiffness and lower moisture resistance; PA12 GF remains the preferred choice where long-term hydrolysis resistance is required. In low-volume assembly tooling that replaces machined aluminium, the polymer can reduce mass by more than 50%, but the substitution is valid only for short-run or contoured fixtures where the lower modulus of the polymer is acceptable. Any aluminium-to-PA6 GF30 replacement should be evaluated for creep under sustained clamping loads and for thermal expansion mismatch with metal inserts.

Chemical resistance of PA6 GF30 follows the polyamide 6 matrix. The material is attacked by strong acids, phenols, and concentrated formic acid; it is not recommended for continuous immersion in strong oxidising agents or in hot aqueous acids. Ultraviolet exposure causes surface embrittlement unless the part is coated or the compound contains appropriate UV stabilisation; the standard black filament supplied for fused filament fabrication is not a UV-stabilised grade unless specifically stated in the supplier documentation. Regulatory compliance must be verified against the current supplier certificate: the product is generally not intended for food-contact or implantable medical use unless specific grade-specific compliance to FDA 21 CFR, REACH, or RoHS has been documented for the finished part. Printing facilities should also treat the glass-filled filament as an abrasive feedstock in material handling systems, because fine glass fibre can accelerate wear in feed tubes and extruder drive gears.