K.-H.

Multi-physical simulation of selective laser melting

Features

Multi-physical simulations are a powerful tool to gain a deeper understanding of selective laser melting as they allow analyzing the influence of process and material parameters on process dynamics and processing result.

Challenges in selective laser melting of refractory metals

In selective laser melting (SLM) a laser beam is applied to build up a workpiece by locally melting up powder layer by layer. The technology principle and the process during operation are shown in Fig. 1. SLM offers unique design possibilities at small lot sizes and is highly material efficient. Especially, SLM of metals offers great potential for future manufacturing technology as it allows the fabrication of fully functional machine and tool parts. Whereas for materials like steel SLM is already well established, commercial systems are available and the technology is on the transition from pure prototype production to industrial fabrication, SLM of refractory metals still poses a challenge, due to their high melting temperature and high thermal conductivity. Nevertheless, SLM offers great potential for the consolidation of high melting point materials as it allows the fabrication of geometrically complex objects that can hardly be fabricated in a classical way. Fig. 2 shows examples of thin-walled grid structures and back tapered machine parts that have been successfully built up by SLM of molybdenum.

In order to overcome the challenges arising during SLM of refractory metals, numerical multi-physical simulations are a powerful tool. They allow to analyze the process dynamics at high spatial and temporal resolution and to study the influence of process parameters. However, modeling laser beam-matter interaction is a challenging task, as it requires a coupling between optics, thermo- and fluid dynamics. Approaches for such a coupled thermo-fluid dynamical modeling of laser material processing have been firstly developed by Mazumder et al. and have been extended to a variety of laser processes including SLM. In the following multi-physical modeling is applied in order to analyze the influence of process parameters and material on process dynamics and melt track width in SLM of steel and molybdenum. The present article is based on results presented at the Euro PM2015 conference in Reims.

Multi-physical simulations are a powerful tool to gain a deeper understanding of selective laser melting as they allow analyzing the influence of process and material parameters on process dynamics and processing result.

Challenges in selective laser melting of refractory metals

In selective laser melting (SLM) a laser beam is applied to build up a workpiece by locally melting up powder layer by layer. The technology principle and the process during operation are shown in Fig. 1. SLM offers unique design possibilities at small lot sizes and is highly material efficient. Especially, SLM of metals offers great potential for future manufacturing technology as it allows the fabrication of fully functional machine and tool parts. Whereas for materials like steel SLM is already well established, commercial systems are available and the technology is on the transition from pure prototype production to industrial fabrication, SLM of refractory metals still poses a challenge, due to their high melting temperature and high thermal conductivity. Nevertheless, SLM offers great potential for the consolidation of high melting point materials as it allows the fabrication of geometrically complex objects that can hardly be fabricated in a classical way. Fig. 2 shows examples of thin-walled grid structures and back tapered machine parts that have been successfully built up by SLM of molybdenum. In order to overcome the challenges arising during SLM of refractory metals, numerical multi-physical simulations are a powerful tool. They allow to analyze the process dynamics at high spatial and temporal resolution and to study the influence of process parameters. However, modeling laser beam-matter interaction is a challenging task, as it requires a coupling between optics, thermo- and fluid dynamics. Approaches for such a coupled thermo-fluid dynamical modeling of laser material processing have been firstly developed by Mazumder et al. and have been extended to a variety of laser processes including SLM. In the following multi-physical modeling is applied in order to analyze the influence of process parameters and material on process dynamics and melt track width in SLM of steel and molybdenum. The present article is based on results presented at the Euro PM2015 conference in Reims.

This article appeared in the September–October 2017 issue of Metal Powder Report.