The Fused Filament Fabrication (FFF) printing process is incredibly adaptable—however, 3D Printer Filament doesn’t work for every plastic. As a result of the tight constraints required to precisely extrude plastic out of a tiny nozzle, traditional plastics originally optimized for injection molding do not print. The plastics that are printable, however, cover a massive range of compositions, print constraints, and material properties. To find the right material, you need to match the requirements of your applications to the properties of the materials you can print with. In this article, we discuss the strengths and weaknesses of a variety of thermoplastics.
In addition to printing thermoplastics, Markforged also adapts the FFF process to print non-plastic materials. In Continuous Filament Fabrication (CFF), an FFF 3D Printer with a specialized second nozzle lays down continuous carbon fiber, fiberglass, or Kevlar® into a part. Atomic Diffusion Additive Manufacturing (ADAM) builds on the existing metal fabrication technology of Metal Injection Molding (MIM), by using an FFF based process to print metal powder encased in a plastic binder. These printed parts are placed in a solvent bath to remove binding material and sintered into fully metallic parts.
Standard thermoplastics
As 3D printing has expanded rapidly, so has the variety of PETG 3D Printer Filaments. Despite this boom, most FFF 3D-printable thermoplastics fit into three categories: basic thermoplastics, niche thermoplastics, and superplastics.
Basic thermoplastics: These plastics don’t have any excellent qualities, but are the most popular printing thermoplastics available. PLA, the most common printing plastic, prints well and possesses decent mechanical properties—however, its complete lack of heat resistance and its low durability makes it impossible to use in industrial environments. ABS has superior heat resistance, but isn’t particularly strong and reacts poorly with most manufacturing chemicals. PETG, a printing subset of polyethylene, is a cross between the two: a bit stronger than ABS and a bit more heat resistant than PLA, but still not robust enough for most manufacturing environments.
Superplastics: These materials possess all the aspects necessary to thrive in manufacturing environments. PEEK and Ultem are both strong, stiff plastics that have extremely high heat resistance and chemical resistance. Engineers used them heavily in manufacturing before they were 3D printable, and now use Multifunctional 3D Printers to create custom, robust fixtures out of these materials.
Continuous fibers (CFF)
While chopped carbon fibers are remarkable in their ability to augment thermoplastics, continuous fibers can add far more strength to parts. Markforged uses a combination of FFF printing and Continuous Fiber Fabrication (CFF) to lay down long strand fibers in conventionally printed thermoplastic parts. This technology is also extrusion based and prints via a secondary nozzle, but instead of melting the whole PCL 3D Printer Filament, it uses the heat of its nozzle to “iron” down fibers into a thermoplastic layer. Fibers do not melt—instead, they’re captured by the thermoplastic matrix in a similar way that thermoset adhesives like epoxy capture fibers in traditional fiber fabrication methods.