Selective laser melting is able to process a variety of alloys, allowing prototypes to be functional hardware made out of the same material as production components. Since the components are built layer by layer, it is possible to design complex freeform geometries, internal features and challenging internal passages that could not be produced using conventional manufacturing techniques such as casting or otherwise machined. SLM produces fully dense durable metal parts that work well as both functional prototypes or end-use production parts.

The process starts by slicing the 3D CAD file data into layers, usually from 20 to 100 micrometers thick, creating a 2D cross-section of each layer; this file format is the industry standard.stlfile used on most layer-based 3D printing or stereolithographytechnologies. This file is then loaded into a file preparation software package that assigns parameters, values and physicalsupports that allow the file to be interpreted and built by different types of additive manufacturing machines.

With selective laser melting, thin layers of atomized metal powder are evenly distributed using a re-coating mechanism onto a substrate plate, usually metal, that is fastened to an indexing platform that moves in the vertical (Z) axis. This takes place inside a chamber containing a tightly controlled atmosphere of inert gas, either argon or nitrogen at oxygen levels below 1000 parts per million. Once each layer has been distributed, each 2D slice of the part geometry is fused by selectively melting the powder. This is accomplished with a high-power laser beam, usually any tterbium fiber laser with hundreds of watts. The laser beam is directed in the X and Y directions with two high frequency scanning mirrors and remains in focus along the layer utilising an F-Theta lens arrangement. The laser energy is intense and focused enough to permit full melting (fusion) of the particles to fore a solid structure. The process is repeated layer after layer until the part is complete.

SLM machines predominantly uses a high-powered Yb-fiber opticlaser with standard laser powers ranging from 100 - 1000W. Inside the build chamber area, there is a material dispensing platform and a build platform along with a recoater system (blade or roller) used to evenly spread new powder across the build platform. . Parts are built up additively layer by layer, typically using layers 30-60 micrometers thick.

Sources: https://en.wikipedia.org/wiki/Selective_laser_melting