Onyx CFF-KV
Reinforced grade
also Markforged Onyx, Onyx CF
CFF-KV = onyx + Continuous Kevlar
Pick for impact-absorbing, abrasion-prone or shock-loaded parts where ductile failure is preferred over brittle carbon fracture.
Values for the CFF-KV condition
Other Onyx grades and fills
Onyx is listed in 8 conditions; see the grade overview at Onyx.
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
As PrintedDefault standard Onyx, no continuous fiber | Default choice for jigs, fixtures and covers where stiffness and surface finish matter more than ultimate strength. | 37 | 40 | 25 | 80 Shore D |
Onyx ESD | Choose for electronics handling fixtures, wafer/PCB tooling and any part that must bleed off static charge. | 42 | 42 | 12 | 80 Shore D |
Onyx FR | Pick when the printed part must meet UL 94 V-0 flammability, e.g. electrical enclosures and rail/industrial interiors. | 48 | 50 | 8 | 82 Shore D |
Onyx FR-A | Use for aircraft interior brackets and tooling where FST/FAR 25.853 vertical burn compliance and material traceability are required. | 48 | 50 | 8 | 82 Shore D |
Onyx + Continuous Fiberglass | Lowest-cost continuous reinforcement: strong but much less stiff than carbon, and electrically non-conductive. | — | 590 | 3.8 | 84 Shore D |
high strength / high temperature fiberglass | Choose when reinforced parts see elevated temperature or need higher impact toughness than standard fiberglass. | — | 600 | 4.2 | 84 Shore D |
CFF-KVThis page Onyx + Continuous Kevlar | Pick for impact-absorbing, abrasion-prone or shock-loaded parts where ductile failure is preferred over brittle carbon fracture. | — | 610 | 2.7 | 82 Shore D |
Onyx + Continuous Carbon Fiber | Use when a printed part must replace machined aluminium in stiffness/strength; values apply along the continuous fiber direction only. | — | 800 | 1.5 | 85 Shore D |
What is Onyx CFF-KV?
Onyx CFF-KV is Onyx in the CFF-KV grade — pick for impact-absorbing, abrasion-prone or shock-loaded parts where ductile failure is preferred over brittle carbon fracture. Onyx CFF-KV has a yield strength of 37 MPa (5.37 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 84% of composite grades. Elongation at break is 2.7% and the elastic modulus is 27 GPa (3.92 Msi). Onyx CFF-KV has a density of 1.2 g/cm³ (0.0434 lb/in³), lighter than 79% of composite grades. Its glass-transition temperature is 60°C (140 °F). As Printed is the default condition FabDigit quotes; CFF-KV is available on request or by drawing note.
Advantages
- Lightweight — 1.2 g/cm³ (0.0434 lb/in³), better than 79% of composite grades
Limitations
- Limited service temperature — 105°C (221 °F), worse than 90% of composite grades
- Low strength — 37 MPa (5.37 ksi), worse than 84% of composite grades
- Low fracture toughness — 3.5 MPa·√m (3.19 ksi·√in), worse than 77% of composite grades
Onyx CFF-KV properties
Typical room-temperature values for Onyx CFF-KV; 19 are specific to this condition. Other listed values are Onyx reference data and may not represent this condition. Bars are the position among composite grades.
Physical5
Onyx CFF-KV has a density of 1.2 g/cm³ (0.0434 lb/in³), lighter than 79% of composite grades. Its glass-transition temperature is 60°C (140 °F).
Mechanical12
Onyx CFF-KV has a yield strength of 37 MPa (5.37 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 84% of composite grades. Elongation at break is 2.7% and the elastic modulus is 27 GPa (3.92 Msi).
Thermal8
Onyx CFF-KV is rated for continuous service to 105°C (221 °F). It conducts heat at 0.3 W/m·K (0.173 BTU/hr·ft·°F), worse than 63% of composite grades. Thermal expansion is 45 µm/m·K (25 µin/in·°F).
Electrical1
Onyx CFF-KV has an electrical resistivity of 1×10¹⁰ Ω·m.
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-KV takes about 135 MJ of energy and emits 8 kg of CO₂ — less than 55% of composite grades. Typical recycled content is 0%.
Manufacturability4
Onyx CFF-KV's machinability is poor (25/100, worse than 65% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Onyx CFF-KV
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-KV — frequently asked
What is Onyx CFF-KV used for?
Onyx CFF-KV is typically used for jigs, fixtures and tooling. In short: carbon-filled tough nylon.
What is the yield strength of Onyx CFF-KV?
Onyx CFF-KV has a typical yield strength of 37 MPa (5.37 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 84% of composite grades. Strength varies by condition: see the 8 listed tempers.
Is Onyx CFF-KV easy to machine?
Not especially — machinability is rated poor (25/100, worse than 65% 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-KV 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-KV?
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-KV 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-KV?
Onyx CFF-KV is rated for continuous use to about 105°C (221 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Onyx As Printed and Onyx FR?
As Printed is the default condition — default choice for jigs, fixtures and covers where stiffness and surface finish matter more than ultimate strength. FR: pick when the printed part must meet UL 94 V-0 flammability, e.g. electrical enclosures and rail/industrial interiors. Yield strength is 37 MPa in As Printed versus 48 MPa in FR.
Can FabDigit make parts in Onyx CFF-KV?
Yes — Onyx CFF-KV 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.