BASF 3D Ultrafuse PC GF30 is a short-glass-fiber-reinforced polycarbonate compound produced for fused filament fabrication. The material consists of a polycarbonate continuous phase with 30% by weight glass fiber reinforcement and is supplied as conditioned filament in nominal diameters of 1.75 mm and 2.85 mm. The conditioned state is process-relevant because polycarbonate is hydrolytically sensitive at the extrusion temperatures required for FFF. When residual moisture enters the melt above 250 °C, the carbonate linkage can hydrolyze, reducing molecular weight and producing gas that appears as splay, porosity, and surface roughness. The glass fiber fraction changes the mechanical response from a ductile thermoplastic to a stiff, dimensionally stable engineering material. Representative published datasheet values for the 30% glass-filled grade, tested according to ISO 527-2:2012 and ISO 178:2019, place tensile modulus in the approximate range of 5,000 MPa to 6,500 MPa and flexural modulus in the approximate range of 6,000 MPa to 7,000 MPa. Elongation at break is generally below 5%. These figures are representative rather than design allowables because fused filament part properties depend on print orientation, chamber environment, moisture history, and printer calibration. The product is specified for manufacturing aids, assembly jigs, inspection fixtures, robotic end-effector components, and functional prototypes in which unfilled polycarbonate exhibits excessive deformation under load or insufficient dimensional stability at elevated temperature.

How does 30 weight percent glass fiber alter the mechanical response relative to unfilled polycarbonate?

The glass fiber reinforcement increases tensile and flexural modulus by roughly a factor of two to three relative to unfilled polycarbonate. The modulus gain is accompanied by a pronounced reduction in ductility. Unfilled polycarbonate can show elongation at break greater than 50% under ISO 527-2:2012, whereas the GF30 grade typically fails at elongation values below 5%. Notched impact strength is also lower, and the fracture mode shifts toward brittle fiber-matrix pullout. The coefficient of linear thermal expansion decreases relative to unfilled PC, which improves dimensional stability in jigs subjected to ambient temperature swings. Heat deflection temperature under load increases with glass fiber content. Published values for this grade are typically reported in the range of 130 °C to 145 °C under ISO 75-2:2013 at 1.82 MPa, compared with approximately 120 °C to 130 °C for unfilled polycarbonate. In FFF, the fiber orientation is anisotropic. Fibers align primarily along the deposition direction during nozzle flow, so the highest tensile properties occur in the XY print plane. Interlayer regions in the Z direction remain the weakest plane because they depend on polymer chain diffusion across the layer interface rather than continuous fiber load transfer.

Compared with carbon-fiber-reinforced polycarbonate grades, the glass fiber system remains electrically insulative. This is beneficial in electronic assembly fixtures where unintended conductive paths must be avoided, but it is a limitation where electrostatic discharge or EMI shielding is required. Glass fiber also provides lower modulus than a comparable carbon fiber grade, but the cost is generally lower and the electrical isolation is more predictable. Compared with injection-molded 30% glass-filled polycarbonate, the FFF product does not provide the same transverse mechanical properties because fused filament parts contain layer interfaces and process-induced porosity.

Moisture conditioning, drying thresholds, and hydrolysis kinetics

Polycarbonate is hygroscopic, and the carbonate linkage is susceptible to hydrolysis when the resin is heated above its glass transition temperature in the presence of moisture. A commonly cited processing threshold for polycarbonate is 0.02% moisture by weight. Above this level, extrusion at 270 °C to 290 °C can generate carbon dioxide and bisphenol A degradation products, producing splay, filament diameter instability, and molecular weight loss. The GF30 product is supplied in conditioned packaging, but the spool should be dried before use according to the manufacturer’s recommendation of 80 °C for 4–8 h in a desiccant or vacuum dryer. The dryer should deliver air at a dew point of -30 °C or lower. A forced-air convection oven is not equivalent because ambient air at high relative humidity cannot reduce moisture content to the same level. If filament is exposed to relative humidity above 60% for more than 30 min after drying, re-drying is required. Moisture uptake at the fiber-matrix interface can be locally higher than in the bulk polymer, and damaged fiber sizing can accelerate water ingress. Delamination at the fiber surface is a known failure mode when wet filament is printed at high temperature. Polycarbonate filament should be fed from a sealed dry box during long production runs to maintain the conditioned state.

Residual moisture is often verified by Karl Fischer titration or weight-loss analysis. The dried filament should not remain exposed on the machine spool holder overnight in an uncontrolled environment. The glass fiber itself does not hydrolyze, but the polycarbonate matrix and the glass fiber sizing are both moisture-sensitive. Extrusion of wet material also increases nozzle pressure fluctuation because vaporization occurs inside the hot end. This produces inconsistent flow and can cause the extruder drive gear to skip on the filament. The result is a pattern of under-extrusion and weak weld lines that may not be visible on the part surface but reduces mechanical integrity.

Processing of the conditioned GF30 grade requires a hardened nozzle orifice of 0.6 mm or larger. The use of a 0.4 mm orifice increases the probability of fiber agglomerate clogging and accelerates nozzle wear. Extruder drive wheels should be hardened steel or hardened stainless steel because the filament is abrasive. The build plate should be maintained at 100 °C to 120 °C with a polycarbonate-compatible adhesive or PEI surface. Printing speed is typically 30 mm/s to 60 mm/s depending on part geometry and layer height. Layer heights between 0.15 mm and 0.25 mm are common. A heated chamber at 80 °C is recommended for parts exceeding approximately 100 mm in the longest dimension. The stiff filament is more brittle than unfilled PC, so spool paths should avoid bends tighter than approximately 100 mm radius. Fiber orientation follows the print path; for load-bearing parts, the deposition direction should be aligned with the principal stress direction where possible.

If the build chamber cannot maintain 80 °C, interlayer fusion becomes the controlling failure mode

Fused filament fabrication relies on the previously deposited layer remaining above the glass transition temperature long enough for polymer chain diffusion across the interface. Polycarbonate has a high glass transition temperature near 147 °C. When a newly deposited layer at 270 °C to 290 °C is quenched by ambient air, the interface may not reach full molecular interpenetration. Z-axis tensile strength can be 30% to 60% lower than XY-plane values under these conditions. This is an inherent anisotropy of the FFF process rather than a filament defect. Large flat parts with continuous beads are especially susceptible to warp-induced delamination at the corners because differential cooling generates residual stress. A heated chamber at 80 °C reduces the cooling rate and allows more complete stress relaxation. If a heated chamber is unavailable, the printing process should use an enclosed draft shield, reduced part-cooling fan speed, and a brim or sacrificial skirt to manage shrinkage. For critical load-bearing jigs, specimens should be printed in the target orientation and tested according to ISO 527-2:2012 or ASTM D638-14 before production release. Published data for z-axis fatigue and creep performance of this specific filament are limited; design allowables should be generated on the target printer rather than extrapolated from injection-molding datasheets.

Abrasive wear and hardware compatibility in production extrusion cells

The 30% glass fiber by weight corresponds to a lower fiber volume fraction because E-glass has a density near 2.54 g/cm³ while polycarbonate matrix density is near 1.20 g/cm³. The calculated fiber volume fraction is approximately 17 vol%. Even at that volume fraction, the glass fiber produces significant abrasive wear in the filament path. Brass nozzles can show measurable bore enlargement after less than 1 kg of material throughput, shifting the effective die diameter and altering extrusion width. Hardened steel, tungsten carbide, or ruby nozzles are preferred. Because hardened steel has lower thermal conductivity than brass, nozzle temperature settings may need to be raised by 5 °C to 10 °C to maintain consistent melt temperature. The abrasive wear mechanism is not limited to the nozzle orifice; fiber bundles also abrade the extruder drive gear, the heat break, and the Bowden tube entry. Plastic drive gears and soft steel hot-end components are unsuitable. In production cells where multiple materials are run on one machine, the hot end should be purged with unfilled polycarbonate or a dedicated cleaning filament before and after the GF30 grade to reduce glass-fiber residue. Dust contamination should be avoided because particulate debris accelerates wear and contributes to clogging.

Chemical exposure limits are determined by the polycarbonate matrix. The material is not recommended for contact with ketones such as acetone or methyl ethyl ketone, chlorinated solvents, strong alkalis, or amine-based cleaning agents because these can produce environmental stress cracking or hydrolysis. It is also not recommended for repeated steam sterilization or prolonged exposure to hot water above 60 °C because hydrolysis can occur. Glass fiber reinforcement does not confer electrical conductivity, so the material should not be used where electrostatic discharge is required. If an application requires ESD behavior, a carbon-fiber-reinforced polycarbonate grade should be evaluated. The product should be stored in a sealed container with desiccant at 15 °C to 25 °C and protected from light. Post-processing by sanding or machining can generate glass fiber dust; engineering controls should be used to limit inhalation exposure. Regulatory status should be verified through the BASF safety data sheet and product regulatory declaration, including REACH and RoHS status, because final part compliance depends on the complete material formulation and the conditions of use.