Onyx · reinforced grade
Onyx CFF-CF
Properties of the CFF-CF condition, compared with the other Onyx grades.
Use when a printed part must replace machined aluminium in stiffness/strength; values apply along the continuous fiber direction only.
What is Onyx CFF-CF?
Onyx CFF-CF is Onyx in the CFF-CF grade — use when a printed part must replace machined aluminium in stiffness/strength; values apply along the continuous fiber direction only. Onyx CFF-CF has a yield strength of 40 MPa (5.8 ksi) and a tensile strength of 800 MPa (116 ksi) — weaker than 100% of composite grades. Elongation at break is 1.5% and the elastic modulus is 60 GPa (8.7 Msi). Onyx CFF-CF has a density of 1.4 g/cm³ (0.0506 lb/in³), lighter than 65% of composite grades. Its glass-transition temperature is 60°C (140 °F). As Printed is the default condition FabDigit quotes; CFF-CF is available on request or by drawing note.
Limitations
- Low strength — 40 MPa (5.8 ksi), worse than 100% of composite grades
- Limited service temperature — 110°C (230 °F), worse than 88% of composite grades
Onyx CFF-CF properties
Typical room-temperature values for Onyx CFF-CF — 8 properties are specific to this condition; the rest are grade-level values shared by every Onyx grade. Each bar shows where the value sits among the composite grades in FabDigit's library — further right is higher.
Physical5
Onyx CFF-CF has a density of 1.4 g/cm³ (0.0506 lb/in³), lighter than 65% of composite grades. Its glass-transition temperature is 60°C (140 °F).
Mechanical9
Onyx CFF-CF has a yield strength of 40 MPa (5.8 ksi) and a tensile strength of 800 MPa (116 ksi) — weaker than 100% of composite grades. Elongation at break is 1.5% and the elastic modulus is 60 GPa (8.7 Msi).
Thermal7
Onyx CFF-CF is rated for continuous service to 110°C (230 °F). It conducts heat at 0.35 W/m·K (0.202 BTU/hr·ft·°F), better than 50% of composite grades. Thermal expansion is 45 µm/m·K (25 µin/in·°F).
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of composite grades. UV resistance is fair.
Sustainability3
Producing a kilogram of Onyx CFF-CF takes about 135 MJ of energy and emits 8 kg of CO₂ — less than 56% of composite grades. Typical recycled content is 0%.
Manufacturability3
Onyx CFF-CF's machinability is fair (35/100, better than 50% of composite grades).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Onyx grades and fills
Onyx is also supplied in 7 other conditions. The full side-by-side table is on the Onyx overview.
- As PrintedDefaultDefault choice for jigs, fixtures and covers where stiffness and surface finish matter more than ultimate strength.40 MPa tensile
- CFF-CFUse when a printed part must replace machined aluminium in stiffness/strength; values apply along the continuous fiber direction only.800 MPa tensile
- CFF-HSHT-FGChoose when reinforced parts see elevated temperature or need higher impact toughness than standard fiberglass.600 MPa tensile
- FRPick when the printed part must meet UL 94 V-0 flammability, e.g. electrical enclosures and rail/industrial interiors.50 MPa tensile
- ESDChoose for electronics handling fixtures, wafer/PCB tooling and any part that must bleed off static charge.42 MPa tensile
Working with Onyx CFF-CF
Is Onyx easy to machine?
Drilling/reaming and light milling are fine with sharp carbide tools, but the chopped carbon fiber is abrasive and cutting into sparse infill exposes voids — design in solid regions where you plan to machine.
Can Onyx be welded?
Not weldable in the metal sense; parts are joined with cyanoacrylate/epoxy adhesive, threaded inserts or mechanical fasteners after light surface abrasion.
Can Onyx be formed, bent or molded?
Processed only by FFF extrusion at roughly 260–285 °C on Markforged printers; dry the spool before use, keep walls ≥ 4 layers and orient loads in-plane to avoid weak Z-axis interlayer failure.
What surface finishes work on Onyx?
Prints leave a matte black surface that needs no painting; sanding, filling and adhesion-promoter primer are required if coating, and no anodizing/plating applies.
Onyx chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| chopped (micro) carbon fiberloading not published by producer; SDS indicates <20 wt% | 5 – 20 | 12 |
| polyamide (PA6/PA66) matrixsemi-crystalline nylon copolymer base resin | balance | — |
Onyx CFF-CF — frequently asked
What is Onyx CFF-CF used for?
Onyx CFF-CF is typically used for jigs, fixtures and tooling. In short: carbon-filled tough nylon.
What is the yield strength of Onyx CFF-CF?
Onyx CFF-CF has a typical yield strength of 40 MPa (5.8 ksi) and a tensile strength of 800 MPa (116 ksi) — weaker than 100% of composite grades. Strength varies by condition: see the 8 listed tempers.
Is Onyx CFF-CF easy to machine?
Not especially — machinability is rated fair (35/100, better than 50% of composite grades). Drilling/reaming and light milling are fine with sharp carbide tools, but the chopped carbon fiber is abrasive and cutting into sparse infill exposes voids — design in solid regions where you plan to machine.
Can Onyx CFF-CF be welded?
Not weldable in the metal sense; parts are joined with cyanoacrylate/epoxy adhesive, threaded inserts or mechanical fasteners after light surface abrasion.
What surface finishes work on Onyx CFF-CF?
Prints leave a matte black surface that needs no painting; sanding, filling and adhesion-promoter primer are required if coating, and no anodizing/plating applies.
Can Onyx CFF-CF be formed, bent or molded?
Processed only by FFF extrusion at roughly 260–285 °C on Markforged printers; dry the spool before use, keep walls ≥ 4 layers and orient loads in-plane to avoid weak Z-axis interlayer failure.
What is the maximum service temperature of Onyx CFF-CF?
Onyx CFF-CF is rated for continuous use to about 110°C (230 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Onyx CFF-CF?
Yes — Onyx CFF-CF is available for 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Markforged Composites Material Datasheet (Onyx, Onyx FR, Onyx ESD, CFF fibers) — Markforged (2023)
- Onyx Safety Data Sheet / filament technical bulletin — Markforged (2022)
- ASTM D638 / D790 / D256 / D648 test methods referenced by the producer — ASTM International (2022)
- Engineering property data for carbon-fiber-filled polyamide (matrix baseline values) — ASM International / CAMPUS polymer data (2020)
- 3D Markforged Onyx (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.