Onyx
also Markforged Onyx, Onyx CF
Onyx is a chopped micro-carbon-fiber filled nylon (PA6/PA66 matrix) filament for Markforged FFF printers, printable on its own or with continuous carbon, glass, HSHT glass or Kevlar fiber laid into the part.
Values for the As Printed condition
Onyx grades and fills
Onyx is supplied in 8 conditions, soft to hard. As Printed is the default FabDigit quotes; the values on this page are for it.
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 | |
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?
Onyx is a chopped micro-carbon-fiber filled nylon (PA6/PA66 matrix) filament for Markforged FFF printers, printable on its own or with continuous carbon, glass, HSHT glass or Kevlar fiber laid into the part. Printed parts are matte black at 40 MPa tensile strength, 2.4 GPa modulus and 25% elongation with service to 110 °C, noticeably stiffer and more dimensionally stable than unfilled nylon, which suits jigs, fixtures and short-run functional parts. Limits are cost, the closed Markforged ecosystem, pronounced Z-axis anisotropy, and a nylon matrix that absorbs moisture and is sensitive to UV and strong acids. FR, FR-A and ESD variants cover flame and static requirements. Onyx 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). Onyx has a yield strength of 37 MPa (5.37 ksi) and a tensile strength of 40 MPa (5.8 ksi) — weaker than 84% of composite grades. Elongation at break is 25% and the elastic modulus is 2.4 GPa (0.348 Msi).
What is Onyx used for?
- Jigs
- Fixtures
- Tooling
Advantages
- Ductile — tolerates forming and impact — 25%, better than 98% of composite grades
- Lightweight — 1.2 g/cm³ (0.0434 lb/in³), better than 79% of composite grades
Limitations
- Limited service temperature — 110°C (230 °F), worse than 87% of composite grades
- Low strength — 37 MPa (5.37 ksi), worse than 84% of composite grades
- Low stiffness — 2.4 GPa (0.348 Msi), worse than 83% of composite grades
- Low fracture toughness — 3.5 MPa·√m (3.19 ksi·√in), worse than 77% of composite grades
Onyx properties
Typical room-temperature values for Onyx-As Printed; bars are the position among composite grades.
Physical5
Onyx 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 has a yield strength of 37 MPa (5.37 ksi) and a tensile strength of 40 MPa (5.8 ksi) — weaker than 84% of composite grades. Elongation at break is 25% and the elastic modulus is 2.4 GPa (0.348 Msi).
Thermal8
Onyx 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).
Electrical1
Onyx 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 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's machinability is good (55/100, better than 71% of composite grades).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. Onyx is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Onyx
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.
Manufacturability
The process limits FabDigit's quote engine applies to Onyx. Design inside these and the part quotes instantly; outside them it routes to an engineer.
3D printing
| Technologies | FDM |
|---|---|
| Layer height | 20 – 60 µmdefault 30 µm |
| Minimum wall / feature | 0.5 / 0.3 mm |
| Build envelope | 250 × 250 × 325 mm |
| Supports | Yes |
| Anisotropy | Mild |
| Mandatory post-processing | heat treatment + HIP |
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 |
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.
Surface treatments FabDigit runs on composite parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Coating
Coloring
Metallization / Functional
Equivalent designations
Standards and trade names that resolve to Onyx in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Markforged OnyxOnyx CF
- Also called
- Nylon CF Filament
How much does Onyx cost?
Onyx is a high-cost composite ($$$$), pricier than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Onyx — frequently asked
What is Onyx used for?
Onyx is typically used for jigs, fixtures and tooling. In short: carbon-filled tough nylon.
What is the yield strength of Onyx?
Onyx has a typical yield strength of 37 MPa (5.37 ksi) and a tensile strength of 40 MPa (5.8 ksi) — weaker than 84% of composite grades. Strength varies by condition: see the 8 listed tempers.
Is Onyx easy to machine?
Reasonably — machinability is rated good (55/100, better than 71% 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 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?
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 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?
Onyx 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.
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.
How much does Onyx cost?
Onyx is a high-cost composite ($$$$), pricier than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in Onyx?
Yes — Onyx 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.