Directed energy on powder layers
"Powder bed fusion", "Selective Laser Sintering", "Selective Laser Melting", "(Selective) Electron Beam Melting"
Metal powder, sometimes polymer powder, is deposited in layers onto a bed, and an energetic beam of light (eg. from a laser) or electrons is used to sinter or melt the powder where it hits, leaving a solidified track of material. As the conversion is localized to a single point or line, toolpath generation is required to scan the desired cross-section area and contour lines to be rendered solid.
Directed energy, directed material stream
"Directed-Energy Deposition"
A stream of material powder is aimed at a weld puddle heated by an energetic beam of laser light or electrons. Requires toolpath generation.
Photopolymerization
"Stereo Lithography", "Digital Light Processing®"
The process uses liquid photosensitive resins that are selectively activated and cured by light to form solid material. The conversion may be localized to a point if the light source is a narrow beam, requiring toolpath generation, or may happen for the whole layer at once if the light source is capable of projecting an image. The material conversion may happen at the air-resin boundary surface, and the part thus generated is lowered deeper into the resin vat as the solid layers build up, or it may happen by exposure through a window at the bottom of the vat, with the part being pulled upwards, away from the window, as the layers are rendered.
Manufacturer-specific workspaces
Example: HP Jet Fusion
The HP Jet Fusion printers fuse powder from layers using heat as well as liquid agents. This workspace connects to these printers via network.