3D Printing is a field of rapidly growing significance that offers advantages attractive to the Engineering profession. The global 3D Printing market size was estimated to be worth $11.58 billion in 2019 and is projected to reach $35.38 billion by 2027. It is worthwhile to have an understanding of such a potentially revolutionary field, especially for Professional Engineers, many of whom are already working with this technology. 3D Printing does not require different molds or tooling for each revision of the design, enabling much faster iterations during the design phase. Additionally, complex geometry is possible with 3D Printing, allowing the combining of parts, which isn’t true for traditional injection molding. As interest and market viability for 3D Printing grows, so too will its relevance in a myriad of uses and applications.

Three processes of 3D Printing have become popular: fused deposition modeling (FDM), selective laser sintering (SLS), and stereolithography (SLA). A key issue affecting market viability for all three technologies is production speed. The printing speed of FDM is between 50 to 150 mm per hour, 48 mm per hour for SLS, and 14 mm per hour for SLA.

Fused deposition modeling (FDM), the most common technology used in desktop 3D printers, uses a thermoplastic filament, which is heated to its melting point and then extruded through a nozzle, layer by layer, to create a three-dimensional object. FDM supports acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) types of materials.

SLS utilizes tiny particles of plastic, ceramic, glass, and metals and fuses them together by heat from a high-power laser to form a solid, three-dimensional object. The first layer of powdered material is evenly rolled onto the build platform, after which the layer of the 3D model is fused together by a laser. Next, the build platform is lowered by the width of one layer, and the next layer of powder is rolled into position. This process is repeated until the 3D object is finished. Since the object is surrounded by (unused) material throughout the duration of the build, support structures are not necessary like they sometimes are with the FDM process. SLS is a faster process than FDM and supports a larger variety of materials, such as polymers (such as nylon or polystyrene) and steels, titanium, and alloy mixes.

Stereolithography (SLA) cures and hardens excess plastic liquid to form a solid, three-dimensional object. SLA supports photopolymer materials that differ in how the layers are built. The build platform is lowered into a bath that is filled with a special liquid photopolymer resin. The resin is light-sensitive and becomes solid when exposed to a laser beam. Each cross-section of the 3D model is traced onto the layer of cured resin that came before it. This is repeated, layer by layer, until the 3D object is completed. Like SLS, SLA is a faster process than FDM. Also, whereas FDM builds the object from the bottom up, SLA builds it from the top down.

Large-scale production and assembly cannot be feasibly accomplished with the current capabilities of FDM, SLS, and SLA technologies, but there are new methods of 3D printing that are emerging and expanding the landscape. This post serves to provide a brief introduction of the most popular and established methods of 3D Printing. Have you had any experiences, positive or negative, with 3D Printing? Feel free to share your insights below.