2.2.2　Geometric model of the L-PBF printer

Fig.2-2 presents a geometric model of a self-developed L-PBF printer.The model is fabricated using two gas pipes, a main chamber and a workbench.The inlet pipe is comprised of a condenser and two intake ducts: Inlet 1 and Inlet 2.The size of the main chamber is 440 × 782 × 483 mm3, with the planar size of the workbench being 255 × 255 mm2.The diameter of the inlet and outlet pipes is 72 mm while the height of Inlet 1 and the outlet are 30 mm and 40 mm, respectively.The intake gas velocity of the L-PBF printer is chosen as 4 m/s.

Fig.2-2　Geometric model of the L-PBF printer

Inert gases have a wide range of applications in industrial engineering because of their chemical inactivity.The laser in the L-PBF printer generates high-temperature areas during the printing process, which could cause metals to readily react with air and this adversely affects product quality.Therefore, the chamber should be filled with an inert gas such as argon.There are some assumptions for the model listed as follows:

(1) All spatter particles inject with the same initial velocity along each direction.

(2) The wall of the printer chamber is set as ideal trapping boundary conditions regardless of the particle velocity.

(3) The shielding gas in the chamber is incompressible.

(4) The effect of metal evaporation is not considered.