Most metal 3D printing technologies can be divided between powder bed and powder / wire systems. In powder bed systems, the feed material used is powder-formed; a thin layer of powder is distributed over a flat surface and other parts of the surface are melted or bonded to the vertical cross-section of the final component. This cycle is repeated as many times as possible and a layer is generated with each iteration.
Powder / wire fed systems can use either metal powder or wire as feed material. The difference between the powder bed methods is that the material is continuously supplied by the printing head and melted to form a suitable shape. The most common method in this category is the Direct Metal Deposition (DMD) process.