Selective Laser Sintering (SLS) is a 3-dimensional printing process based on sintering, using a laser beam directed by a computer onto the surface of metallic or non-metallic powders selectively to produce copies of solid or surface models.
The process operates on the layer-by-layer principle. At the beginning a very thin layer of heat fusible powder is deposited in the working space container. The CO2-laser sinters the powders. The sintering process uses the laser to raise the temperature of the powder to a point of fusing without actually melting it. As the process is repeated, layers of powder are deposited and sintered until the object is complete. The powder is transferred from the powder cartridge feeding system to the part cylinder (the working space container) via a counter rolling cylinder, a scraper blade or a slot feeder. In the not sintered areas, powder remains loose and serves as natural support for the next layer of powder and object under fabrication. No additional support structure is required. An SLS system contains also an atmosphere control unit that houses the equipment to filter gas recirculated from the process chamber. It also maintains a set temperature on the air flowing into the process chamber.