Solid-Based Additive Manufacturing Systems

Stratasys Fused Deposition Modeling (FDM)

Fused deposition modeling is a layer AM process that uses a thermoplastic filament by fused deposition. FDM was trademarked by Stratasys Inc. in the late 1980s and a similar term is FFF. The filament is extruded from a nozzle to print a cross-section of an item and then travels up vertically to replicate the procedure with a new layer (Figure 4.1).

The most frequently used FDM materials are ABS, PLA, and PC (polycarbonate), but new blends containing wood and stone as well as rubber-like filaments can be found. Compared to ABS, PLA reacts differently to moisture, to UV ageing with discoloration, and to material removal. In order to forecast the mechanical behavior of the FDM components, it is important to understand the material properties of the raw FDM process material and the effect that FDM builds parameters have on the properties of anisotropic materials (Ahn et al. 2002). The support material is often made from another material and is detachable or soluble from the actual material at the end of the manufacturing process (with the exception of low-cost solutions using the same raw material). The disadvantages are that the resolution on the z-axis is low compared to the other AM process (0.25 mm); therefore, if a smooth surface is needed, a finishing process is needed, and it is a slow process that sometimes takes days to build large, complex parts (Wong and Hernandez 2012).

FDM technology is the most popular 3D desktop printer and the cheapest professional printer to date. FDM was invented in the 1980s by Scott Crump (1992, 1994). The main strength of FDM lies in the variety of the materials and the efficient mechanical properties of the resulting components that have been produced using this technique. Components manufactured using FDM are among the best components for any polymer-based additive manufacturing process. The main drawback to the use of this technology is the speed of construction. The inertia of the plotting heads means that the maximum speeds and accelerations that can be achieved are slightly lower than other instruments. In addition, FDM allows information to be plotted in a point-wise, vector-mode that involves a number of directional changes.