Transient simulation of particle transport and deposition in the laser powder bed fusion process: A new approach to model particle and heat ejection from the melt pool

Abstract

Ensuring consistent product quality and reproducibility is of paramount importance in additive manufacturing. This applies in particular to the laser powder bed fusion procedure. Process parameters, such as laser power, scanning strategy or inert gas properties, affect the generation of emissions and by-products such as spatters and fumes and their removal from the process chamber. Numerous authors investigated these effects in numerical studies to predict suitable process parameter sets. However, the basic challenge of modelling time-dependent particle and heat ejection from the moving melt pool region as well as predicting of the resulting transport and deposition mechanisms with sufficient accuracy still remains. In this context, an approach of modelling the statistical particle ejection as well as underlying heat transfer into the process chamber through analytical considerations is presented. Particle transport and deposition are numerically investigated for the case of a real case of application. Several production layers are covered in one transient simulation, assessing the influence of different scanning strategies. Especially the effect of convective flow caused by high heat influx through the melt pool is investigated. Results are compared to data obtained from an associated experiment. The presented model enables numerical simulation of arbitrary scanning patterns and laser properties without the need for preceding experimental studies determining pattern specific ejection rates.