Three dimensional printing (3D printing or 3DP), called also as additive manufacturing, is the way of manufacturing by creating a 3D solid object from a digital model by building layers. This technology becomes more and more popular in different areas of the human activity, such as automotive, medicine, education etc.
The main innovation of this technology is connected with a new approach to production process. It could be slightly different for each type of 3D printing process. The first stage is producing a 3D model using CAD software. This model could be designed with 3D scanning, invented by designer or based on other project. The next stage is conversion to the standard tessellation language (STL) format. Most 3D printers use STL files. Next, the file is transferred to the computer that controls the 3D printer. At this moment, it is possible to make some changes in the object, by setting-up the device, such as size. After that, the process is starting. The 3D printer should be checked regularly during this time to make sure that there are no errors. After the process is finished, the printed object is removed from the device. The last step is post-processing, for example brushing off any remaining powder or curing.
The whole manufacturing process could be different, because different techniques are applicable in 3D printing. According to ASTM (the American Society for Testing and Materials) standard there are seven categories of additive manufacturing:
- Vat Photopolymerisation, including Stereolithography (SLA), Digital Light Processing (DLP) and Continuous Liquid Interface Production (CLIP),
- Material Jetting,
- Binder Jetting,
- Material Extrusion, including Fused Deposition Modeling (FDM) and Fused Filament Fabrication (FFF),
- Powder Bed Fusion, including Multi Jet Fusion (MJF), Selective Laser Sintering (SLS) and Direct Metal Laser Sintering (DMLS),
- Sheet Lamination,
- Directed Energy Deposition.
In case of construction industry three of them are applicable:
- material extrusion for different materials: concrete/cement, wax, foam, polymers,
- powder bed fusion, called also powder bonding for polymer bond, reactive bond, sintering,
- additive welding.
Material extrusion is nowadays the most applied technique. In that technology, the material is extruded from a nozzle mounted on a gantry to print a structure layer by layer.