Additive manufacturing is building its way into more projects, on the shop floor and at home.

The word “manufacturing” may bring to mind images of factories housing huge machines in an assembly line creating one item thousands of times. But in the past decade, the rise of 3-D printing has brought manufacturing into homes and small businesses, allowing users to bring to life on a desktop any item they can dream up with a CAD program. Composites companies are jumping into the field, too, by 3-D printing items with reinforced fibers.

A Brief History of 3-D

The MarkOne may not look so different from other desktop 3-D printers, but it’s the first one to print carbon fiber composites continuously.

The MarkOne may not look so different from other desktop 3-D printers, but it’s the first one to print carbon fiber composites continuously.

While the term “3-D printing” permeates the press, it was originally coined by MIT to describe polymer-based desktop models. 3-D printing falls under the larger umbrella of additive manufacturing, the industry term for all applications of technology that use a process of joining materials to make objects from 3-D model data, usually layer upon layer. Additive manufacturing only uses what material is needed, in contrast to subtractive manufacturing, which involves cutting parts away from a larger chunk of material to create the desired final product.

Excitement surrounding additive manufacturing has spiked in the last two years, but early equipment and materials have existed since the 1980s. Chuck Hull of 3D Systems Corporation invented a process known as stereolithography in 1984, in which layers are added by curing photopolymers with UV lasers. He also developed the STL (STereoLithography) file format widely used by 3-D printing software as well as digital slicing and infill strategies common to many processes.

A 3-D printer creates an object by following the STL file’s instructions to lay down successive layers of liquid, powder, paper or sheet material in a series of cross sections. These layers correspond to the virtual cross sections from the CAD model and are joined or automatically fused to finish the object. The material enters an extruder via a funnel where the material is heated to its melting point and pressed together to form a homogeneous liquid. The printer head extrudes the melted material along the paths in the STL file on the X and Y axes before moving up one step along the Z axis.

A variety of materials can be used in additive manufacturing processes, including metals, polymers and fibers. Discontinuous strands of carbon fiber or fiberglass are most frequently used to reinforce plastics in 3-D printing processes across every market sector, including automotive, aerospace, tooling, medicine and infrastructure. These reinforcements deliver the strength of composites with less material in less time and can be designed and prototyped from one desktop.