| Summary: | A uniform distribution of power density (energy flux) in a stationary laser beam leads to a decrease in the overheating of the material in the center of the laser beam spot during laser powder bed fusion and a decrease in material losses due to its thermal ablation and chemical decomposition. The profile of the uniform cylindrical (flat-top) distribution of the laser beam power density was compared to the classical Gaussian mode (TEM<sub>00</sub>) and inverse Gaussian (donut) distribution (airy distribution of the first harmonic, TEM<sub>01*</sub> = TEM<sub>01</sub> + TEM<sub>10</sub>). Calculation of the Péclet number, which is a similarity criterion characterizing the relationship between convective and molecular processes of heat transfer (convection to diffusion) in a material flow in the liquid phase, shows that the cylindrical (flat-top) distribution (TEM<sub>01*</sub> + TEM<sub>00</sub> mode) is effective in a narrow temperature range. TEM<sub>00</sub> shows the most effective result for a wide range of temperatures, and TEM<sub>01*</sub> is an intermediate in which evaporation losses decrease by more than 2.5 times, and it increases the absolute laser bandwidth when the relative bandwidth decreases by 24%.
|
|---|