A tour around the world of 3D-printing technologies: Extrusion Deposition Modeling

Denis PryadkoAugust 9, 2015

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Hello! I’m glad you’ve found this article. In this series of articles I’ll do my best to make an interesting and succinct tour around the rich and colorful world of 3D-printing technologies, following on my previous article, which I named “3D-printing: what it is and why is it so exciting”. Let’s get started!

As I wrote before, 3D-printing as a technology is very general, and one can come up with countless ways to implement it. Basically, the only requirement for any manufacture technology to be called a 3D-printing technology is that new material should be gradually added to the part, usually layer by layer, as opposed to subtracting material from an initial piece.

It makes sense to divide all that diversity of technologies into a few categories:

Extrusion deposition
Light polymerization
Powder bed
Lamination

Extrusion deposition

Extrusion deposition modeling, and in particular, Fused Deposition Modeling (FDM), is currently the most popular 3D-printing technology, especially when it comes to consumer-grade 3D-printers. Almost all of the consumer-grade 3D-printers are currently using FDM technology. It short, an FDM 3D-printer fuses a thermoplastic material (usually a thermoplastic filament wound on a spool) and then pushes it through the nozzle that moves above the 3D-printing bed. The movement of the nozzle is predefined by a computer in such a way that the deposited material forms the desired object.

Here is a video that clearly shows the process of printing a part on an FDM 3D-printer:

Aside from the fact that FDM is very easy to implement, the patents protecting this technology had expired, triggering development of a large open-source community, and both commercial and DIY 3D-printers utilizing this technology appeared on the market in huge numbers.

The material used in FDM printing process is usually common plastic, and that is another advantage of FDM. For instance, some 3D-printers use photocurable resins that imitate plastic instead, but in some regards they are not as good as real common ABS or PLA plastic. There is a whole spectrum of various plastics for FDM with different properties.

One of the downsides of FDM technology is low speed. For large parts printing process might take tens of hours! In order to boost the speed and cut material costs and the weight of the printed part, people usually print things in sparse mode. That is, instead of printing them as a bulk piece of plastic, the object is designed to have a honeycomb-like interior.

Usually the process of turning a computer 3D model of a solid object into a sparse object model is done automatically by a special computer program. Users can adjust various settings such as porosity and the type of the honeycomb-like pattern depending on how strong, how light they want their model to be and how much time they are willing to wait for the detail to get printed.

(picture: sparse models with various settings).

Materials:

Extrusion deposition modeling 3D-printers can print with a wide variety of materials. Basically, everything that can be extruded will do. For example, 3D-pinters printing with food are becoming more and more popular these days. Even metal things can be printed using this technology if one uses metal clay. There were a few tries to print metal objects on FDM printers more directly by melting the metal first, but they were not much of a success, primarily because another 3D-printing technology turned out to be much better suited to the task of printing with metal.

Also, there’s the possibility of printing plastic molds for casting objects from varius materials, including metal (alhtough for metal they usually use molds 3D-printed from ceramics), thus not only manufacturing metal objects with the help of a 3D-printer, but doing it fast besides.