Multi-scale simulation approach for the prediction of overheating under consideration of process parameters in powder bed fusion of metals using a laser beam

Abstract

Powder bed fusion of metals using a laser beam (PBF-LB/M) allows for the tool-free manufacturing of complex parts. During the PBF-LB/M process, local overheating can negatively affect the part quality, which results in an increased surface roughness or the formation of shrink lines. Process simulations are used to predict overheated regions and to initiate suitable countermeasures before the manufacturing process. For large-scale parts, in particular, simplifying heat source models are applied to ensure an appropriate computing time. However, these simplifications partially neglect the consideration of the impact of the process parameters on the thermal behavior. In this work, a physics-based multi-scale simulation approach is presented for the time-efficient prediction of geometry-induced overheating for large-scale parts. The presented methodological approach can be applied for different process parameters, materials, and PBF-LB/M machines. For this purpose, a thermal simulation was set up to determine the thermal behavior of a single layer using a moving heat source. By means of an analytical model, the heat source for the simulation of large-scale parts was adapted so that the thermal behavior of the single layer and the impact of the process parameters are represented. The simulation demonstrated that local and global heat accumulations can be predicted independently of the build platform occupancy. The results identified the overheated regions determined in the experiment. The application to a topology-optimized industrial part confirmed the computational efficiency. In the future, this simulation model can be used for the reliable prediction of overheating-caused defects and to allow for a first-time-right manufacturing.