**3.2 Direct metal deposition additive manufacturing**

Direct Metal Deposition (DMD) additive manufacturing method was invented by Precision Optical Manufacturing (POM). The metallic powder or wire used in the DMD is sprayed directly onto the laser beam or the electric arc beam. The beam melts the metallic powder or wire by the laser or electric arc heat source, then the molten metal drops on bed to build the part layer by layer. Because of that, it is called direct deposition process and not powder bed in DMD. There is a possibility to build multilateral parts from various metallic alloys. To produce complex geometry parts, the nozzle is placed onto a 5-axis CNC machine to offer more flexibility in the movement of the nozzle. Several factors control this method of MAM: layer thickness, deposition rate, nozzle feed rate, laser power, gas flow, and the gap between the nozzle and printing surface [3]. The DMD can be divided into several processes; the next sub-section outlines the main processes of DMD.
