Obsidian PA6+CF (Alternative to ONYX Markforged)

3DXtech is a technical filament manufacturer from the United States, in business since 2014. They focus their efforts on coming up with innovative polymer filaments and custom blends that satisfy highly advanced functional needs arising in the additive manufacturing market. 3DXtech has a wide range of materials including technical and advanced materials and support filaments. In their own words, 3DXtech’s products target "difficult end-use applications where functionality is king." Their specialty are filaments enriched with carbon fibers, such as the Obsidian PA CF filament.

3DXtech's Obsidian PA6 CF filament was developed to be a cheaper drop-in substitute for the Markforged Onyx filament (>30 % savings), compatible with all Markforged 3D printers and any printer that can print PA6 CF filaments. The Obsidian PA CF is made up of >80 % PA6 copolymer and <20 % premium high-modulus carbon fiber.

Image 1: Part printed with the Obsidian PA CF. Source: 3DXtech.

Nylon (PA) is a synthetic polymer from the polyamide group. It is an affordable and highly versatile material extensively used in 3D printing due to its durability, flexibility, thermoplasticity, and resistance to abrasion, shock, friction, corrosion and chemicals. Its first uses were mainly in the consumer goods industry (toothbrushes, women’s stockings), but nylon quickly found other more advanced uses, for example to make parachutes, ropes, body armor and helmet liners for the US army.

Nowadays, nylon has uses as diverse as fishing lines, guitar strings, zips, food industry products, surgical products, screws, industrial machinery, automotive and aerospace industry, and sports.

In 3D printing, it can be found in the form of powder (SLS and MJF), pellets, and filament (FDM). The main kinds of nylon used in 3D printing are the PA12 variety (automotive, machinery, industry) and the PA6 variety. PA6, also known as polycaprolactam, is the most extensively used polyamide thanks to its great performance/cost ratio. It is distinguished by its toughness, short- and long-term heat resistance, resistance to aliphatic hydrocarbons (oil/gas/lubricants), great surface and processability quality, and yield strength.

The addition of carbon fibers

Filaments with technical applications are often reinforced with carbon fibers or glass fibers to better equip the filament for the task it is designed to perform. Adding carbon fiber (CF) makes the filament more stiff and more dimensionally stable, which translates into a reduced risk of warping. Pieces printed with CF-enriched filaments are a great substitute for metal parts due to reduced weight. Those properties make plastic reinforced with CF perfect for the automotive industry (high tensile strength and modulus, high temperature tolerance and low thermal expansion) and the aerospace industry (weight reduced up to 50 % with preserved functionality).

Image 2: Size comparison of a carbon fiber and a human hair. Source: 3DXtech.

3DXtech’s Obsidian PA6 CF

This PA6 CF filament is reinforced with 5-10 μm wide carbon fibers, aligned following the axis of the filament, which gives the material great structural properties, mechanical and thermal properties, bringing out the best in the nylon and the carbon fibers. The Obsidian PA6 CF is characterized by low warping, low shrinking, low CTE (coefficient of thermal expansion), and great material flow, which makes it an easy filament to 3D print.

This material is ideal both for prototyping and for the production of end-use parts. It is also possible to produce complex parts with a 3D printer with a dual extruder, using Obsidian PA6 CF as the build material in one extruder and a support filament in the other. The recommended support filament for this material is the water soluble AquaTek X1 UMS support filament.

The Obsidian PA6 CF is ideal for 3D printing elements that must be rigid but also lightweight, which makes it the material of choice for aerospace, civil engineering, the military and motorsports.