Extrusion (FDM / FFF)

Fused Deposition Modeling

Fused Deposition Modeling (FDM) is a 3D Printing process in which a physical component is directly fabricated from a computer-aided design (CAD) file using layer-by-layer deposition of a feedstock plastic filament material extruded through a nozzle.
Fused Deposition Modeling (FDM)/ Fused Filament Fabrication (FFF) is one of the most widely used additive manufacturing processes. The technology is often leveraged for the manufacturing of prototypes and functional parts in engineering plastics. Due to their ability to produce complex geometrical shapes without tooling in office-environment, FDM 3D Printers are often the first choice of most users.
The easy-to-use process, its reliability and affordability have made the success of AM and have fostered the adoption of technology in industries, academia and among consumers. It is often the first choice of beginners in the 3D Printing industry. R&D institutions still leverage this technology for the development of new materials and processes.
The most widely used materials are thermoplastic polymers (e.g., PLA, ABS, polyurethane). They appear in the form of a pre-extruded filament. In the process below, a coil of thermoplastic filament is first loaded into the system. Once the nozzle has reached the ideal temperature, the filament is fed to the extrusion head, then in the nozzle where it melts. The extrusion head is attached to a two-axis system that facilitates its move in x-y directions.
The melted material is extruded in thin strands and deposited layer-by-layer in preselected areas, as described in the STL file. Sometimes, the cooling of the filament on the platform is accelerated through the use of cooling fans attached on the extrusion head. When a layer is finished, the build platform moves down in z-direction, and a new layer is deposited. This process is repeated until the part is complete.
The FDM process was first developed and commercialized by Stratasys in 1992. Over the years, the development of the process allowed new companies into this segment.

Fused deposition modeling: (A) scheme of the process; (B) example of PCL structure obtained by FDM, scale bar 500 μm (Zeina et al., 2002).