3D printers are reinventing industries by enabling designers to test ideas, and allowing manufacturers to produce and take them out to market faster than ever before. There are different 3D printing technologies available. The right one for you will depend on what you wish to print. In this article we will look at 5 revolutionary 3D printing technologies, broadly divided into 2 groups:
Extruder based 3D printers
Laser based 3D printers
Makerbot is a price competitive FFF 3D printer. (P2) Image courtesy Access Industrial Systems
Extruder Based 3D Printers
Extruder based 3D printers include both FDM® (Fused Deposition Modeling) printers and FFF (Fused Filament Fabrication) printers. FDM® technology was developed by Scott Crump, the founder of Stratasys Ltd, in the 1980s. As ‘Fused Deposition Modeling’ and its abbreviation FDM are proprietary terms of Stratasys, other printers using similar technology refer to their process as ‘Fused Filament Fabrication’ or FFF.
Working principles of an FDM/FFF 3D Printer (P3)
How Do Extruder Based 3D Printers Work?
First, a special software “slices” the virtual (CAD) model into layers. Then the printers build objects layer by layer from the bottom up by heating and extruding a thermoplastic filament onto a printing platform or base. The two horizontal coordinates of the model control the movement of the printer’s extruder, while its vertical coordinate determines how much the printing base moves down.
The printers uses 2 spools of filaments.(1)One spool is the printing material – a thermoplastic – which comes in a variety of mechanical, thermal, and chemical characteristics. The other spool is a support material. This material is used in conjunction with the thermoplastic as a support, to help the printer create more complex structures. It can be dissolved after the print process, once the thermoplastic has hardened.
FDM® 3D printers print with a diverse range of high performance, engineering grade thermoplastics, making them the prefered choice of many engineers and manufacturers. On the other hand, FFF printers are the choice of many hobbyists and schools due to their relatively cheaper price tag.
Metal Lattices printed by Selective Laser Melting (SLM) Printers (P4)
Laser Based 3D Printers
Laser based 3D printers include Selective Laser Sintering (SLS), Selective Laser Melting (SLM), and Stereolithography (SLA) 3D printers. Of these, SLS and SLM 3D Printers are similar as they print 3D objects from material powders, while SLA printers print their objects from a liquid resin.
Mechanism of SLS 3D printer (P5)
Selective Laser Melting (SLM) & Selective Laser Sintering (SLS) 3D Printers
Selective Laser Sintering (SLS) printers have the capability to print using traditional industrial materials such as ceramics, metals alloys, and plastics. These printers are generally very expensive as they use a high powered pulsing laser to fuse together the powdered material, layer by layer, into the desired three dimensional shape. After the laser fuses the powder for one layer, the powder bed is lowered to allow a new layer of material to be applied on top, and so on until the object is completed.(2) This process can be seen in the diagram above.
The mechanism of Selective Laser Melting (SLM) 3D printer is very similar to that of SLS printer, except its laser is more powerful. Powerful enough to melt the powder together. This allows SLM printers to print with elemental metal powders and not just with alloys like SLS printers. (3) The resulting prints are much denser and better suited for even the most demanding applications. (4) It isn’t then a surprise that these printers are the most expensive on this list.
One of its main advantages of both these printers is that the unused powder remains as is, and becomes a support structure for the object. It can also be used for the next print, leaving no waste. This is exciting considering the traditional machining of industrial materials, such as metals, is subtractive and extremely wasteful.
The form 2 is a popular low cost Stereolithograph (P6)
Stereolithograph 3D Printers (SLA)
As mentioned before the technology behind Stereolithography (SLA) printers is different to SLS and SLM 3D printers. The difference being that this printer’s laser binds together a liquid resin, rather than a powder, to create a 3D model. It was one of the first 3D printing technologies developed, and its name stems from the Greek words “stereo,” meaning solid, and “(photo)lithography,” which is a form of writing with light. (5) Owing to the fact that it binds the liquid resin at a layer thickness a fraction of a millimeter, the resulting prints are very high quality 3D models that require less post processing to achieve a professional finish.