Direct Metal Deposition process (DMD) is one of the most advanced methods of additive manufacturing of three-dimensional metal components. Major industries such as aircraft, automotive, shipbuilding and military industries are among the leading users of this technology. This process, by laser irradiation to the surface and simultaneous spraying of the powder, melt the substrate and, by feeding of the powder into the molten pool and its rapid cooling rate, creates a frozen metal pathway. The applications of this method include the building of three-dimensional parts, repair, rebuilding, and cladding the surfaces. Due to the need for this technology in the country and its applications, the design and fabrication of this technology were considered in this experimental study. In the first step, the design and fabrication of the DMD system was carried out by Nd: YAG pulsed laser system with a maximum power of 300 watts. After initial adjustments and starting up the device, 316L stainless steel alloy powder was used for production of three-dimensional samples. In order to construct optimal three-dimensional components, the full factorial approach in design of experiment method was used and the effective process parameters, such as powder flow rate and laser speed, were identified and then optimized. After optimization of the parameters, manufacturing of the three-dimensional components was performed by adjusting the appropriate layer thickness, adjusting the laser path compensation and measuring the dimensional accuracy. Then the effect of the scanning pattern of the laser was examined and the density of each pattern was measured. The results showed that the powder flow rate as the input parameter in the process had more effect than the laser speed. Also, the three-dimensional components made by this method had a density of nearly 98% and good strength, which is an indication of the optimality of the parameters. The samples had a columnar microstructure with directional dendritic cells. Hot tearing cracks were indicative of high input energy in the upper layers. The dimensional accuracy of the samples made, along the axis X and Y for external dimensions was less than 0.4 millimeters. Also, the surface roughness of the samples was below 70 ?m. Keywords: Nd: YAG pulsed laser system, design fabricating direct metal deposition system, process parameters optimization, stainless steel 316L, mechanical properties microstructure
