14. An Approach to Numerical Modeling of Temperature Field in Direct Metal Laser Sintering

Direct metal laser sintering (DMLS) is an advanced manufacturing process in the class of modern additive manufacturing, which produces three-dimensional complex shapes from the powder material in a layered approach. It plays a significant role to manufacture metallic components directly from the metallic powders. Technological parameters of direct metal laser sintering determine the quality of the parts produced, i.e., porosity, residual stresses, and strength. The qualities of build parts are dependent on thermal and sintering behavior, which directly affected by the process parameters. In this process, a high-energy laser beam was utilized as the heat source to melt and fuse the powder particles and hence builds the three-dimensional solid object. To control the quality of the build parts, it necessitates to fundamentally understand the heat transfer mechanism. In this process, rapid heating and cooling take place which results in an unexpected change in temperature in the scanned layers. This change in temperature persuade thermal stresses in the build part after the accomplishment of the process, and it can be destructive to the quality and performance of the build parts which hinders its end-user applications. In response to this fact, it is important to analyze the heat transfer mechanism during the direct metal laser sintering process. The present research work focused on to simulate the three-dimensional transient temperature field in the build part in direct metal laser sintering of AlSi10Mg alloy powder by using ANSYS platform. The model consists of a stainless steel substrate with the dimension of 3 mm × 3 mm × 2 mm and AlSi10Mg powder layer having the dimension of 3 mm × 3 mm × 1 mm. The simulations were carried out by considering radiation, convection, and temperature-dependent thermo-physical properties of alloy powder. The heat source was presumed as the Gaussian heat source. The temperature variation, thermal history, molten pool dimension, and sintering depth with respect to process parameters in the direct metal laser sintering process were investigated. From the simulation result, the temperature profile along the scanned layers was predicted as a function of process parameters. It has been observed that with the increase in scan speed from 100 to 400 mm/s, the temperature in the build part decreases from 1483 to 1196 °C and reverse phenomena was observed with increase in laser power. Similarly, the sintering depth of the powder bed increases from 0.061 to 0.872 mm with the increase in laser power from 50 to 130 W. This model will act as an important tool for the design and optimization of process parameters in DMLS process.