Basic principles of fused deposition modeling

Fused deposition modeling (FDM), also known as fused filament fabrication (FFF), is a widespread additive manufacturing (AM) technology belonging to the family of “material extrusion” (ME) methods. The conventional feedstock in FDM is a thermoplastic (or wax) filament of standard diameter of either 1.75 mm or 2.85 mm. However, a key advantage of FDM is the ability to process thermoplastic-matrix composites, which enables the production of complicated objects with bespoke functionality and even the fabrication of fully inorganic parts. In principle, printing an object by FDM is relatively simple. The filament is fed into the printer and pushed into the liquefier by counter-rotating gears. After melting, the feedstock flows through the print nozzle and lends onto the base platform according to a computer-controlled path. The process is repeated layer upon layer, until the desired three-dimensional geometry is completed. Dual-nozzle printers allow multi-material printing. However, in spite of its apparent easiness, the part's build-up is actually a complex process governed by numerous, and often inter-related, variables. After introducing the basics of FDM, this chapter details how to print an object and what parameters should be considered to reach the desired performance.