A Parametric Study of Powder Bed Temperature Distribution in Selective Laser Sintering Process

This study aimed to numerically evaluate the effects of various encapsulation gas parameters on the powder bed temperature distribution (which is crucial for the quality of the manufactured products’ mechanical properties) in the SLS process. The simulations were validated with experimental data obtained from thermal photographs. A parametric study was conducted considering three main factors: gas type, pressure, and heat capacity, which were examined separately. It was observed that among the four gases of argon, ambient air, nitrogen, and helium, the most and the least uniform temperature distributions in the powder were related to helium and argon, respectively. In particular, it was seen that the standard deviation of the temperature of the points located on the powder surface decreased from 3.69 for Argon to 2.98 °C for helium (19.8% decrease). Moreover, the number of points within 4 °C from the final desired temperature increased from about 43 for argon to about 57.2% for helium. As for the gas pressure, it was seen that there is a direct relationship between pressure and the uniformity of the powder temperature distribution. In particular, the standard deviation of the temperature of the points located on the powder surface is decreased from 3.99 for the pressure of 0.4 atm to 3.16 °C for 2 atm (20.8% decrease). Moreover, the number of points within 4 °C from the final desired temperature increased from roughly 40.8 for 0.4 atm to about 48.2% for 2 atm. And finally, as for the gas heat capacity, increasing the gas heat capacity during the preheating process up to a value equal to the heat capacity of the air (while the other gas features were kept unchanged) increases the uniformity of the temperature distribution, whereas increasing the heat capacity beyond that value decreases the uniformity.