Polymaker PolyMide™ PA6-GF is a fused-filament-fabrication grade composed of polyamide 6 reinforced with short E-glass fibers at a nominal loading of 15 wt%. The product is supplied in nominal 1.75 mm ± 0.05 mm and 2.85 mm ± 0.10 mm diameters on sealed spools containing desiccant; net spool weights are 1 kg and 3 kg. The filament is intended for extrusion through an all-metal hot end fitted with a hardened steel nozzle of 0.4 mm orifice diameter; brass, aluminum, or copper-alloy nozzles are unsuitable because the glass filler abrades the orifice and alters dimensional output. Because hardened steel has lower thermal conductivity than brass, the hot-end setpoint may be increased by 5–10 °C when changing from brass. Manufacturer-published processing values include nozzle setpoint 280–300 °C, build-plate setpoint 25–50 °C, and part-cooling fan output 0–30 %. Pre-print drying is specified at 80 °C for 12 h in a forced-air oven. Dried material is stored below 20 % RH and is fed from a sealed dry box when ambient humidity exceeds 60 % RH. The dry density is approximately 1.24 g/cm³ by ISO 1183-1. Glass fiber dispersion is achieved during twin-screw compounding; no further mixing is required at the FFF print head. The single-screw extruder in the print head conveys and melts the filament but does not further disperse the fiber. Batch-to-batch fiber-length distribution is not published for this specific configuration; users should monitor nozzle pressure and filament diameter variation as indirect indicators.

What Distinguishes PolyMide™ PA6-GF from Unreinforced PA6 and Carbon-Fiber-Filled PA6?

At the matrix level, polyamide 6 is semicrystalline and hygroscopic. At 23 °C and 50 % RH, the unreinforced matrix takes up approximately 2.5–3.0 wt% water according to conditioning under ISO 62, while saturation in liquid water can exceed 9 wt%. Glass fiber reduces the total linear moisture expansion because the inorganic phase has negligible water uptake, but it does not interrupt hydrogen bonding between water and the amide carbonyl. Unreinforced PA6 provides higher elongation at break and better ductile failure, but it exhibits stronger crystallization shrinkage and edge-lift on large-section prints. PolyMide™ PA6-CF replaces glass fiber with chopped carbon fiber; the carbon-filled grade is specified for higher tensile and flexural modulus and shows reduced electrical surface resistivity. PA6-GF remains insulating, which is relevant for electrical tooling, power-electronics fixtures, and transformer assembly jigs where unintended current leakage cannot be tolerated. Compared with PolyMide™ PA12-CF, the PA6-GF grade has higher equilibrium moisture uptake and requires more aggressive moisture control; however, dry-state heat deflection temperature and tensile modulus can exceed those of PA12-based materials when printed in equivalent X-Y orientation. The comparison is qualitative and should not replace lot-specific datasheet verification.

Moisture control is the first-order variable in processing PolyMide™ PA6-GF. A spool removed from a dry box at 60 % RH can regain printable-limit moisture within 30 min. The failure is not merely surface bubbles: dissolved water in the PA6 melt attacks the amide bond through hydrolysis, reducing number-average molecular weight, lowering melt viscosity, and generating steam at the nozzle. The process signature is a combination of uncontrolled oozing during travel moves, microvoid concentration at the interlayer weld, and a measurable loss of Z-direction tensile resistance. The specified 80 °C for 12 h forced-air drying is a minimum boundary condition; a static oven without positive air exchange cannot transport water away from the spool surface efficiently. If the operating floor exceeds 60 % RH, the filament should be printed directly from a dry box with a dew point below -20 °C. Desiccant alone is insufficient to strip water from filament that has been exposed to humid ambient air for more than a few minutes; desiccants maintain dryness but are not effective bulk regenerators for saturated PA6. Moisture above 0.2 wt% should be avoided before entering the hot end. The use of a hygrometer and a sealed storage bin with silica or molecular sieve is not optional when processing PA6-GF in coastal or uncontrolled plant air.

If a Heated Build Chamber Is Not Available, Warp and Interlayer Welding Are Controlled by Print Parameters

Polyamide 6 crystallizes during cooling and undergoes a larger specific-volume change than amorphous thermoplastics; the glass fiber reduces the linear coefficient of thermal expansion and the observable curl, but it does not eliminate residual stress in a thick section. Parts with floor areas above 100 mm × 100 mm or aspect ratios above 3:1 should be printed with a brim or raft, and the ambient air around the machine should be shielded from drafts. The build-plate setpoint of 25–50 °C is below the dry glass-transition temperature of PA6, so adhesion is primarily a function of the adhesive film and first-layer geometry rather than polymer chain mobility at the bed interface. A PVA-based adhesive film on glass or textured PEI is used; bare glass is not a reliable substrate. First-layer height for a 0.4 mm nozzle is set to 0.2 mm, with first-layer speed reduced to 20 mm/s. Fan output is held at 0 % for the first 3 layers; after that, fan speed above 30 % on large-section parts creates differential shrinkage between the outer shell and the warmer core and can initiate interlayer peeling.

Interlayer welding in PA6-GF is diffusion-controlled at the polymer–air interface. The temperature at the weld zone must remain above the glass-transition temperature and below the thermal-degradation onset for sufficient contact time. At 280 °C, interfacial diffusion is slower and Z-direction tensile strength can fall below the datasheet X-Y value; at 300 °C, the polymer has higher chain mobility, but the thermal margin to PA6 degradation narrows. Extended residence time above 300 °C may produce yellowing, carbonized residue, and an acrid odor. The nozzle setpoint alone is not an interlayer warranty; print speed is equally important. Speeds above 60 mm/s reduce weld residence time and are not recommended for load-bearing parts. Direct-drive extruders with minimized filament path length are preferred because the stiff glass-filled filament can be ground or buckled in long Bowden guides. Retraction distance is set to 1–2 mm for direct-drive; long retractions pull molten glass-filled polymer into the cold zone and can nucleate plugging. On production-scale FFF lines, the first observable batch-to-batch fault is often an extruder current excursion or local filament ovality before a mechanical failure; the operator should measure diameter with a micrometer and log spool weight before starting. The purge sequence between PA6-GF and other materials is to run a sacrificial purging compound through the hot end at 280 °C until the extrudate is clear; residual glass fiber in the nozzle can produce cross-contamination and poor weld quality in the next build.

Mechanical Property Reporting Under ISO 527-2 and ISO 178

Mechanical data for filled FFF materials cannot be reduced to a single number. Specimen geometry, print raster, perimeter count, infill overlap, and conditioning state all shift the result. The following manufacturer-published representative values are for flat dog-bone specimens printed in the X-Y plane with 100 % infill, conditioned at 23 °C and 50 % RH for at least 40 h, and tested according to ISO 527-2, ISO 178, ISO 179-1, and ISO 75-2. They are not lot-specific certificate values.

Anisotropy is the dominant limitation. The glass fibers lie predominantly in the print plane; Z-direction interlayer boundaries are resin-rich and weaker. The elongation at break of 3.5 % is typical for filled X-Y specimens but does not hold across a layer boundary. Designers should not use the flexural modulus from the table as a bulk isotropic stiffness. Parts operating at 60 °C or above in the dry state require revalidation because PA6 stiffness decreases with temperature and moisture plasticization. If the component is exposed to saturated humidity or process water, the matrix may take up several weight percent water; the fiber phase suppresses swell but not the resulting plasticization. Published data for fully saturated FFF PA6-GF specific configurations are limited; end-use qualification should be performed under the actual conditioned state.

Factory applications include jigs, fixtures, cable clips, robotic end-of-arm brackets, and non-conductive assembly tools; in each case the part must be tested on the target machine because tolerances shift with moisture state. The material is not recommended for high-frequency fatigue or impact-critical assemblies without a printed notched coupon test under ISO 179-1 at the service temperature.

Annealing PolyMide™ PA6-GF is sometimes used to stabilize dimensions after machining or to raise dry-state heat resistance. A forced-air oven at 80–100 °C for 2–4 h can increase crystallinity and reduce residual stress in the matrix; however, annealed parts shrink anisotropically and can warp if not fixtured flat. Annealing temperature should not exceed 100 °C for unfixtured parts because the glass transition of the dry matrix is 62 °C and large sections may creep under their own weight. After annealing, the part is moisture-depleted and brittle; a conditioning step at 23 °C and 50 % RH for 24–48 h partially restores equilibrium ductility. Water conditioning by immersion accelerates moisture uptake but is not a substitute for standard conditioning when test data are compared to ISO 527-2 because the moisture gradient across the wall is not uniform. If a part will operate in continuous contact with water, an immersion soak at 23 °C until mass stabilizes is a more representative conditioning method but yields lower modulus than the dry table value.

Long-Term Service Exposure and Chemical Contact Require Validation Beyond the Datasheet

PA6-GF is susceptible to the same chemical degradation pathways as unreinforced PA6. Strong mineral acids, formic acid, chlorinated solvents under stress, and some phenolic solutions can degrade the polyamide matrix, while the glass fiber remains relatively inert. Aliphatic hydrocarbons, mineral oils, and many machine coolants are generally less aggressive, but stress cracking under load in the presence of metalworking fluids has not been certified for all formulations. When the product is used as factory tooling, compliance documentation such as REACH and RoHS Directive 2011/65/EU as amended must be verified for the exact spool lot, because polymer additives and sizing chemistry can change without changing the grade designation. The glass reinforcement is electrically insulating; therefore PA6-GF is preferred over carbon-filled polyamide when contact with uninsulated electrical busbars or printed-circuit nodes is possible. However, the material is not a safety-rated electrical insulator, and creepage and clearance distances should follow the equipment standard applicable to the application, such as IEC 60664-1 for low-voltage equipment.

For wear surfaces, glass-fiber-filled PA6 can abrade mating aluminum or polymer parts; for sliding bearings or snap-fit features, unreinforced or self-lubricating grades may be required. The operational temperature floor for load-bearing parts should be validated below 0 °C because the PA6 matrix becomes more brittle and the notch sensitivity of the filled material increases. Printing can be performed without a heated chamber, but parts should not be immediately quenched in water; rapid cooling after deposition increases amorphous content and produces a different dimensional state than an air-cooled control. The operating envelope is therefore defined by the intersection of nozzle temperature, dry filament moisture, and build-plate adhesive condition: if any one of these variables falls outside the published window, the measured mechanical properties and interlayer fracture resistance will shift below the datasheet baseline.