Numerical simulation and experimental investigation of gas–powder flow from radially symmetrical nozzles in laser-based direct metal deposition

Experimental Analysis of the Direct Laser Metal Deposition Process

“…The nozzle can have different configurations. There are two basic ones: with a coaxial supply and a lateral supply of powder (Weerasinghe & Steen, 1983;Zekovic et al, 2007). In the first one, there is the advantages of the independence from the moving direction of the head, of the controlled heating of the powder before it goes into the molten pool and of the high capture efficiency of powder by the molten pool.…”

Monitoring Approach to Evaluate the Performances of a New Deposition Nozzle Solution for DED Systems

“…In particular, the deposition quality can be affected by intrinsic parameters (related to the properties of the substrate and the metallic powder such as geometry, thermal diffusivity, absorptivity, thermal conductivity, and heat capacity) and extrinsic parameters (related to the laser, the powder feeder, and the positioning system). In particular, extrinsic parameters are strictly related to the specific print head of the employed AM machine, in which powder injection nozzles and the laser beam are assembled according different schemes [6]. Indeed, common DED or cladding powder injection systems can present:…”

“…The off-axis powder injection implies a strong relation between the deposition rate and the scan direction [8]; in the continuous coaxial version, as opposed to the discontinuous axial one, the tilting of the powder injection nozzle is restricted, limiting the potentialities of DED [6]. Multiple nozzle deposition is suitable for parts with high geometrical complexity, even if it is more difficult to ensure flow uniformity and direct the powder to a specific region of interest [9].…”

“…Multiple nozzle deposition is suitable for parts with high geometrical complexity, even if it is more difficult to ensure flow uniformity and direct the powder to a specific region of interest [9]. In the case of both continuous coaxial configuration and discontinuous coaxial configuration, the spot of the powder flow in correspondence with the deposition plane usually ranges between 5 mm and 8 mm [6,[10][11][12][13].…”

Effects of substrate preheating on the thin-wall part built by laser metal deposition shaping

“…Nevertheless, they were not concerned with the effects of substrate on the microstructure and performances of formed components. In addition, most researchers pay more attention to the numerical modeling of the thermo-mechanical behavior during the laser additive manufacturing process, but not focus on the influences of substrate temperature on this heat history [15][16][17][18][19]5]. In this work, combined with the numerical simulation model, the LMDS system and a self-developed substrate preheating facility were employed to intensively investigate the effects of substrate preheating on the as-deposited metal parts.…”