PA6CF (Carbon Fiber Reinforced Polyamide 6) for FDM

Material Profile: PA6CF (Carbon Fiber Reinforced Polyamide 6) for FDM

FDM Engineering Material Technical Report Series — Volume 2 of 16

Compiled from manufacturer technical datasheets and peer-reviewed literature

Abstract—PA6CF is a polyamide-6 thermoplastic reinforced with chopped carbon fibre (typically 20 wt%). Compared with PA12CF it offers higher absolute stiffness and HDT due to PA6's higher inherent crystallinity, at the cost of much higher moisture sensitivity. Data are taken from Bambu Lab, Polymaker, and 3DXTech datasheets; values not published by suppliers (especially Z-direction yield strength and elastic limit) are presented as engineering estimates and clearly marked.

Index Terms—additive manufacturing, FDM, carbon-fibre composite, polyamide 6, hygroscopic.

I.  MATERIAL IDENTIFICATION

This section establishes the canonical names and commercial designations under which the material is supplied.

A.  Designation

Trade name: PA6CF (generic). Examples include Bambu Lab PA6-CF, Polymaker PolyMide™ PA6-CF, 3DXTech CarbonX™ PA6+CF.

B.  Full Chemical Name

Matrix: poly(ε-caprolactam), conventionally Polyamide 6 / Nylon 6 (PA6), produced by ring-opening polymerisation of caprolactam. Composite: Carbon-fibre reinforced Polyamide 6 (CF/PA6).

C.  Aliases and Alternative Designations

II.  COMPOSITION AND MOLECULAR STRUCTURE

A.  Empirical Chemical Formula

PA6 repeating unit: [-NH-(CH₂)₅-CO-]ₙ; empirical (C₆H₁₁NO)ₙ. Reinforcement: PAN-derived chopped carbon fibre.

Fig. 1.  Repeating unit / structural schematic of the polymer matrix.

Fig. 2.  Schematic of dispersed reinforcement / filler in the polymer matrix (not to scale).

B.  Composition Breakdown

TABLE I
 COMPOSITIONAL BREAKDOWN OF PA6CF (TYPICAL / PER SUPPLIER DATASHEET)

III.  MECHANICAL PROPERTIES — XZ PRINT DIRECTION

In the XZ orientation the tensile load is applied parallel to the deposited rasters; for fibre-reinforced grades this is the strongest orientation because the fibres align preferentially along the extrusion direction.

TABLE II
 MECHANICAL PROPERTIES — XZ ORIENTATION (PA6CF)

IV.  MECHANICAL PROPERTIES — ZX PRINT DIRECTION

In the ZX orientation the tensile load is applied perpendicular to the print layers, so failure occurs through inter-layer (Z) bonds. Properties are markedly lower than in XZ — this anisotropy is intrinsic to FDM.

TABLE III
 MECHANICAL PROPERTIES — ZX ORIENTATION (PA6CF)

Estimated XZ:ZX UTS ratio ≈ 2.5:1, modulus ratio ≈ 2.9:1. PA6CF shows higher absolute XZ strength than PA12CF due to PA6's higher inherent strength and crystallinity, but is more moisture-sensitive — ZX (interlayer) properties degrade rapidly with humidity exposure.

V.  RECOMMENDED PRINT PARAMETERS

Values summarised below give consensus operating windows from public datasheets. Specific suppliers may differ within ±10 °C; the supplier datasheet always supersedes this table.

TABLE IV
 RECOMMENDED PRINT TEMPERATURE RANGES FOR PA6CF

VI.  GLASS TRANSITION TEMPERATURE (TG)

Reported / typical Tg: ≈ 60 °C (PA6 matrix; CF reinforcement does not significantly shift Tg).

Annealing at 80–100 °C × 4–6 h is recommended for fully crystalline parts. PA6's high moisture sensitivity means parts can absorb 6–9 wt% water at saturation, which depresses Tg by 30–40 °C and modulus by up to 30%. Design must account for service humidity.

VII.  HEAT DEFLECTION TEMPERATURE (HDT)

Heat deflection temperature is the temperature at which a standard bar deflects 0.25 mm under a specified flexural load (ASTM D648 / ISO 75).

TABLE V
 HEAT DEFLECTION TEMPERATURE OF PA6CF UNDER STANDARD TEST LOADS

VIII.  DISTINGUISHING CHARACTERISTICS AND STANDARDS

A.  Higher crystallinity than PA12CF

PA6 has shorter aliphatic spacing (5 CH₂ groups between amides versus 11 in PA12), giving more H-bonding sites and ~30–40% crystallinity in well-annealed parts. This produces higher stiffness and HDT at the cost of brittleness and higher moisture uptake.

B.  Strong moisture sensitivity

PA6 saturates at 6–9 wt% water at 23 °C / 50% RH. Wet specimens lose up to 30% modulus and 20% UTS but gain elongation at break (plasticisation). For dimensional accuracy, parts must be annealed and either kept dry or have dimensions compensated.

C.  Chemical resistance

Resistant to alkalis, alcohols, oils, and most fuels. Attacked by strong mineral acids (sulfuric, formic, hydrochloric) and by halogenated solvents at elevated temperature.

D.  Flammability

Standard PA6CF carries a UL 94 HB rating (slow horizontal burn). Flame-retardant grades (V-0) are commercially available but require explicit selection.

IX.  REPRESENTATIVE APPLICATIONS

PA6CF is typically deployed in the following applications:

1)  Automotive under-hood components: Brackets, intake ducts, fluid containers; PA6 base provides higher temperature resistance than PA12-based composites.

(Source : Incept 3D)

2)  Industrial dynamic-load fixtures: Robot tooling and machine guards subject to repeated impact loading.

(Source : Incept 3D)

3)  Sporting goods and protective gear: Helmets, ski-boot frames, bike components — applications historically dominated by injection-moulded PA6/GF.

4)  Pre-production verification of injection-moulded PA6 parts: PA6CF FDM is often used for design validation before commitment to PA6 mould tooling.

5)  Consumer electronics housings: Hard, paintable surfaces with good stiffness.

Photographs of representative parts in these applications are not reproduced here for copyright reasons; the table below provides direct manufacturer / case-study URLs where original imagery and project descriptions can be viewed.

TABLE VI
 SUGGESTED IMAGE / CASE-STUDY SOURCES

X.  REFERENCES

[1]  Bambu Lab, “PA6-CF Filament Technical Data Sheet,” 2024. https://us.store.bambulab.com/products/pa6-cf

[2]  Polymaker, “PolyMide™ PA6-CF Technical Data Sheet,” 2024. https://polymaker.com/product/polymide-pa6-cf/

[3]  3DXTech, “CarbonX™ PA6-CF Carbon Fibre Reinforced Nylon 6,” 2024.

[4]  ASTM D638-14; ASTM D790-17; ASTM D256-10; ASTM D648-18.

[5]  F. Calignano et al., “Composite Filament Comparison: PA6-CF vs PA12-CF vs PA6-GF25,” Inslogic 3D Tech Note, 2025. https://www.inslogic3d.com/blogs/blog/composite-filament-comparison-for-3d-printing-pa6-cf-vs-pa12-cf-vs-pa6-gf25

[6]  M. Heidari-Rarani et al., “Mechanical characterization of FDM 3D-printed CFRP composites,” Composites Part B, 2019.