Composite Filament Fabrication (CFF)

Process Details

Printer Type:

Composite Filament Fabrication (CFF) is a process developed by Markforged in which continuous strands of fibers are embedded in a thermoplastic matrix to create stiff, strong and extremely durable parts capable of replacing machined aluminum. The base material, a carbon fiber filled polyamide, is deposited using a fused filament fabrication process. A specialized second nozzle selectively lays down continuous fiber reinforcement (typically carbon, Kevlar or fiberglass) in specific locations and orientations.

Visual Aspect: 

The continuous fiber reinforcement is embedded in the part. Only the micro carbon filled base material (Onyx) is visible on the outside. It yields accurate parts with impeccable matte surface finish, superior to conventional FFF/FDM parts.


Bounding Box:

12.6" x 5.2" x 6.0" (320 mm x 132 mm x 154 mm)


  • Minimum layer thickness .0040" (100 µm) unreinforced
  • Typical layer thickness .0050" (125 µm) with continuous carbon fiber reinforcement


XY printing accuracy +/- .0020" (+/- 50 µm)


Lead time will be indicated in your instant quote, typically 3 days.


Product Range: 

  • Our composite base material is Onyx, a micro carbon fiber filled polyamide (nylon). It offers high strength, toughness and chemical resistance. It can be printed alone or with continuous fiber reinforcement.
  • Continuous carbon fiber is extremely stiff and offers the highest strength to weight ratio (flexural strength 540 MPa). It is commonly used for parts that replace machined aluminum.
  • Continuous Kevlar fiber possesses excellent durability, making it optimal for parts that experience repeated and sudden loading (flexural strength 240 MPa).
  • Continuous fiberglass is an entry-level reinforcement material. It is capable of yielding parts 10x stronger than ABS and is more affordable than carbon fiber.

Design Guidelines

Wall Thickness: 

  • Min. wall thickness (reinforced) .102" (2.6 mm)
  • Min. post diameter (unreinforced):
    • XY .063" (1.6 mm)
    • Z .079" (2.0mm

Hole dimensions:

  • Min. hole diameter XY .059" (1.5 mm)
  • Min. hole diameter Z: .039" (1 mm)


Minimum unsupported angle 45°.
Additional design guidelines are available on your customer portal. We provide free DFM feedback and can propose specific fiber reinforcement layouts for your application.



The Onyx base material offers high strength, toughness, and chemical resistance when printed alone. It can be reinforced with continuous fibers to yield aluminum-strength parts.
Housings, brackets and mounts, high-strength tools and fixtures, functional prototypes, end-use parts

Recommended Resources

Materials datasheet

Technical specifications: Onyx, carbon / kevlar / fiberglass reinforcement

Design guidelines

Design guidelines with/without reinforcement, fiber reinforcement best practices

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