So what kinds of printers are there? How do they print and how are they different? The terminology is still a bit confusing. The American Society for Testing and Materials (ASTM International) recently came up with the following categories:
- Material extrusion is also known as Molten Polymer Deposition (MPD), Fused Deposition Modeling (FDM), or Fused Filament Fabrication (FFF); these extrude a gooey material out in layers to build up the proper shape. This is the class of printers that includes most hobbyist 3D printers. They work like the simulator you just used. These can use plastic, metal wire, wax, sugar, frosting, chocolate, cookie dough pasta, pizza, and even corn chips.
- Material jetting is also known as photopolymer jetting. Like an inkjet, this printer squirts liquid photopolymers at the right moment, which are cured immediately with ultraviolet light, layer by layer. The object being built is supported by a layer of gel that is also applied by the print head, so overhang is not a problem.
- Binder jetting uses a two part system. A thin layer of composite material is spread across the print bed. Then, an inkjet-like printing head sprays a binder fluid and possibly colored ink, which combine with the composite material to produce solid colored and sometimes textured objects. This can be plastic, gypsum, or metals, such as copper, tungsten, bronze, and stainless steel. For metals, a second step is needed to make them solid. The binder is removed and metal is infused where the binder used to be.
- Sheet lamination printers may use materials, such as paper or metal, and will color, cut out, and glue layers together into objects.
- Vat photopolymerization is also called Stereolithography (SLA). Photopolymerization printers use light to cure liquid material into the right shape. This process uses resins, wax, or liquid plastics for the material. It may use a laser or a high resolution DLP video projector similar to one you would hook up to your computer to give a PowerPoint presentation.
- Powder bed fusion is also known as Granular Materials Binding. These printers use a laser or heat to fuse layers of powder into the right shape. These can use metal, ceramic, gypsum, or plastic powder. There are several subtypes of powder bed fusion printers.
- Selective Laser Sintering (SLS) is used with thermoplastics, wax, and ceramic powders. A thin coat of powder is spread across the printing bed. Then, the printing head prints the layer by fusing selected areas with the laser. The printing bed then drops down. Another coat of powder is added and the laser prints the next layer.
- Selective heat sintering (SHS) uses heat instead of a laser and can be used with thermoplastic powder.
- Direct Metal Laser Sintering (DMLS) or Selective Laser Melting (SLM) is a subcategory of selective laser sintering. The laser beam melts the metal and makes solid parts with metal alloys like aluminum, iron, stainless steel, maraging steel, nickel, chromium, cobalt, and titanium alloys. In theory, it can be used with most alloys.
- Directed energy deposition, also known as Electron Beam Melting (EBM), is similar to SLS, but uses an electron beam instead of a laser. The high heat generated by the electron beam allows use of pure metal powder such as titanium alloys, and can make high-detail, high-strength objects that do not need any postmanufacturing heat treatment.
Question: Earlier, I mentioned a company named Made In Space, which is making a 3D printer to be used in zero gravity. What kind of printer is it making?
- Directed energy deposition
- Vat photopolymerization
- Material extrusion
- Powder bed fusion
Answer: Option 3, material extrusion is correct. Extruding a material avoids liquid or powder floating around in zero gravity.
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