As with any new technology, 3D printing is developing and evolving, and companies are competing to set what will be the industry standard.
Currently, the most popular way to create prints is to use Polylactic Acid (PLA) as the filament (think ink in regular printers), and a technique known as Fused Deposition Modeling (FDM) to build your model. During this process, layers of plastic as thin as 0.1mm are extruded and stacked on top of each other to create the 3D relief.
At least for the time being, there are three main methods for which to create your 3D printed objects.
The Stereolithography Method (SLA for short) was invented in 1986 by Charles Hull, who also founded the pioneering 3D printing company, 3D Systems. Hull, along with his team at 3D Systems, produced the first commercial 3D printer around the same time. SLA printers work by focusing a concentrated beam of ultraviolet light onto the surface of liquid photo curable photopolymer (resin). Layer by layer the beam “draws” out each slice of the model, hardens it, and bonds it to the layer below. The process repeats and the lazer begins “drawing” the next layer. Unused resin is reusable for the next job.
Fused Deposition Modeling (FDM)
Just like its main rival SLS, Fused Deposition Modeling (FDM) was also invented in the 1980's. This time, its creator was Scott Camp. In 1988 Camp, along with his wife, founded Stratasys; one of 3D printing's leading companies. During FDM the 3D model is produced by first heating and then extruding tiny beads of molten thermoplastic material and layering them, one on top of another. The molten thermoplastic cools and hardens as it leaves the extrusion nozzle. Most FDM printers use ABS plastic, like what is used in LEGO, as well as PLA (Polylactic Acid) which is a biodegradable polymer made from corn.
The actual term “Fused Deposition Modeling” and its abbreviation “FDM” are trademarked by Stratasys.
Selective Laser Sintering (SLS)
Selective Laser Sintering (SLS) is yet another ground breaking 3D printing method to be born out of the 1980's. While Charles Hull and Scott Camp were busy working away on their deisgns, Carl Deckard and colleagues at the University of Texas in Austin were developing SLS. The process is similar to that in SLA manufacturing, however instead of a laser curing liquid photopolymer in a vat, you’ll find powered materials, such as polystyrene, ceramics, glass, nylon, and metals; including steel, titanium, aluminum and silver.
When the concentrated laser touches the powder, it is fused or sintered at that point. The surrounding non sintered powder remains and acts as a support structure to the model. This lack of need for support is a notable benefit over SLA and FDM methods. Nothing to remove and no waste, all unused powder can be used in your next print.