Overview: Top 3D printing processes in 2020
3D printing has the potential to disrupt the manufacturing of just about anything. Yet many of the printing processes are largely unknown…
One device, print everything?! Even though 3D printing has been around since the early 80s, the technology still seems new. This may be because it is nowhere near mature enough to match our imagination. 3D printing processes are constantly evolving. They have to, because they are (still) comparatively expensive. Improvements in hardware meet new technical possibilities from industries such as artificial intelligence, 5G or robotics.
One example: Topology Optimization combines artificial intelligence with 3D manufacturing processes. Using complex mathematical calculations, the perfect structure of an object can be simulated. The model is simply given the “design space”, i.e. the available space, as well as other criteria such as load, stiffness constraints and function. Based on this, the program generates the most effective shape. This can save both material (and thus costs) and weight, and improve the performance of the tools.
What types of 3D printing are there?
ISO/ASTM 52900 was created in 2015 as a standard that attempts to classify the types of 3D printers. Nevertheless, there are many 3D printing processes, also known as additive manufacturing processes, with even more different 3D printing technologies. A very good overview is provided by the 3D printing magazine all3dp.com.
In very simplified terms, 3D printing can be summarized as follows: In all printing processes, material is applied layer by layer to create a three-dimensional object. The final 3D structure is designed on the computer before the actual printing process.
Process #1: Material extrusion
In material extrusion, also called filament 3D printing, filament (the starting material) is melted in the printer’s syringe-like extruder and applied in the predetermined structure. The plastic cools and hardens. In this method, the filament is in roll or rod form. 3D printers for this method are among the most common and cheapest. New approaches to extrusion systems use other materials, such as metals, as well as other curing methods, for example, to 3D print houses (Apis-Cor) or human tissue (Organovo). FDM, the technology behind it, was invented more than 30 years ago by Scott Crumps’ Stratasys.
Types: fused deposition modeling (FDM, also called FFF).
Applications: Temperature-resistant components, high-volume components, fixtures, prototypes.
Process #2: Photopolymerization
In photopolymerization, a light source cures a photopolymer resin layer by layer in a tank. During this process, the object is steadily lifted and dried. The difference between the various types is the light source used to cure the resin. Stereolithography was the world’s first 3D printing technology and was invented by the company 3D Systems.
Types: stereolithography (SLA), masked stereolithography (MSLA), direct light processing (DLP), continuous liquid interface production (CLIP).
Applications: For particularly high detail and smooth surfaces. For example, small pieces of jewelry or dental applications such as dentures.
Process #3: Powder Bed Fusion (Polymers)
Powder Bed Fusion, also known as selective laser melting, creates a solid object by tracing structures in powder with a laser and curing them. Powder is then reapplied and cured again. The object is encased in the unused powder.
Types: selective laser sintering (SLS).
Applications: Complex and functional parts made of nylon
Process #4: Material Jetting
In material jetting, heated resin is “jetted” in small drops onto the printing platform and then cured with a UV light. The many print heads make it possible to combine materials and colors. The pioneer of the Material Jetting printing process is the Stratasys company.
Types: material jetting (MJ), drop on demand (DOD).
Applications: Prototyping, anatomical models, art.
Process #5: Binder Jetting
The filament in powder form is bonded to the liquid binder by the print head along the specified structure. The build platform lowers and the new layer is applied. Although a wide range of materials is available, the use of binders means that the process is not suitable for all components.
Types: Binder Jetting (BJ)
Applications: Prototyping, architecture, automotive
Process #6: Powder Bed Fusion (Metals)
Powder bed fusion for metals works similarly to powder bed fusion with polymers. Instead of nylon, the laser traces the structures into metal powder and cures them. In most cases, post-processing is common.
Types: direct metal laser sintering (DMLS), selective laser melting (SLM), electron beam melting (EBM).
Applications: Heavy, complex and durable metal parts e.g. in aerospace.
Process #7: HP Multi Jet Fusion
In the Multi Jet Fusion process, the print head sprays a liquid (called a “fusing agent”) onto a layer of the material powder. This is then exposed to heat with infrared light and melted. The so-called “detailing agent” is applied, as insulation, around the area. Overall, this still-young process enables higher accuracy, higher resolution and significantly faster printing. As a result, it is currently considered the most productive additive plastic production process.
Applications: Functional (small) series components
Sources
- https://all3dp.com/1/types-of-3d-printers-3d-printing-technology/
- https://www.3dnatives.com/de/3d-druck-durch-polyjetting/#!
- https://www.3d-activation.de/der-3d-druck-blog/8-verschiedene-3d-druckverfahren-in-einer-kaffeelaenge/
- https://3faktur.com/technologieansaetze-im-3d-druck/#:~:text=Das%20mit%20Abstand%20wichtigste%20Verfahren,Kunststoff%20ab%20und%20verfestigt%20sich.
- https://3druck.com/3d-druck-grundkurs/uebersicht-3d-druckverfahren/
- https://einfach3ddruck.de/binder-jetting/
- https://www.3d-grenzenlos.de/3d-druckverfahren/photopolymerisation/
- https://www.twi-global.com/technical-knowledge/faqs/what-is-powder-bed-fusion
- https://engineeringproductdesign.com/knowledge-base/binder-jetting/
- https://3faktur.com/3d-druck-materialien-und-verfahren/hp-multi-jet-fusion-das-verfahren/#1481032334093-9c9cb5b4-6e92
