About a decade ago, the ASTM International defined seven types of 3D printing. Over the years, the additive industry developed more ways to build objects in a layer-by-layer process, and new terms and descriptions were added.
Here’s a look at the 10 major Additive Manufacturing Processes you should know:
1. Binder jetting
An additive manufacturing process that uses a binder that chemically bonds layers of powder. The binder material is jetted through an inkjet technology in a specific pattern for the part.
2. Digital Light Synthesis (DLS)
A variation of vat photopolymerization (which was first labeled stereolithography). This process is based on light projector technology originally developed by Texas Instruments. Ultraviolet light from the projection system shines onto a photosensitive resin held in a vat. An object is built a layer at a time. As with most photosensitive resin systems, this process has a smooth finish where layers are not prominent.
3. Direct Laser Melting (DLM) or Direct Metal Laser Sintering (DMLS)
This is a powder bed fusion process that uses a laser to melt powder material, mostly metal material. Once melted, the layer of powder solidifies onto the layer below, building the desired part layer-by-layer. A new, thin layer of powder material is placed on top in a re-coating move, and the laser moves over the new layer to melt specific sections of the powder onto the previous layers. This process has a number of aliases, including laser powder bed fusion, metal powder bed fusion, and direct metal laser sintering.
4. Directed Energy Deposition (DED)
This additive process jets metal powder onto a build plate or already existing object. Other variations include extruding a wire from a CNC controlled three or five-axis nozzle. This process usually works in combination with a laser or electron beam that melts the powder just before deposition. One of the benefits of this process is that, in addition to building objects, it can be used to repair minor defects or wear and tear in already existing objects.
This process is more popularly known as Fused Deposition Modeling (FDM), a proprietary term of Stratasys, or Fused Filament Fabrication (FFF), the generic term. In this additive process, a continuous filament of thermoplastic material feeds into a heated extruder and is then deposited onto a build plate in a layer-by-layer process.
6. Laser Powder Bed Fusion (L-PBF)
Another type of powder bed fusion process that uses a laser to melt the powder material. It is also known as metal powder bed fusion and direct laser melting. Materials include plastic as well as metal powder.
7. Laser Engineered Net Shaping (LENS)
This process is a form of direct energy deposition (DED) and is also known as laser powder forming. A powder material is jetted and melted with a high-energy source, such as a laser, just before it reaches a build plate or other surface.
8. Material Jetting
An additive process that uses multiple jetting nozzles to deposit build and/or support material in a layer-by-layer build process.
9. Stereolithography (SL)
Usually considered to be a form vat photopolymerization per the ASTM definition, stereolithography was the first form of three-dimensional building of a part, invented and named by Chuck Hull in 1986. It uses photo-reactive (usually acrylic-based) polymers that instantly harden when exposed to an ultraviolet beam.
10. Vat Polymerization
This type of additive manufacturing includes stereolithography and other additive methods that use photosensitive polymers and some type of light source, typically lasers or UV light. Depending on the type of additive vat polymerization device, the build layer can be on top of the vat of liquid or on the bottom.