EOS and Linde combined their respective expertise to jointly undertake research in the field of additive manufacturing and material-gas interaction. The aim of this study was to improve AISi10Mg properties according to customer needs. The influence caused by different impurities of the process gas on the generated material quality as well as the influence on the process itself were analyzed.
In this study the influence of residual oxygen and a special shielding gas mixture during the DMLS® process in relation to the material properties of AlSi10Mg were investigated. With higher oxygen levels the variance of the material properties can increase, as can powder quality and life-cycle due to oxidation.
Nevertheless, in terms of porosity only a minor change in the maximum defect size can be observed when the oxygen level is decreased. Results confirm a quite stable process behavior of AlSi10Mg when using EOS AlSi10Mg powder material, optimized process parameters and the EOS M290.
First analyses of the recorded OT-Monitoring data show a visible influence when using the argon/helium mixture. Special gases like these have a slightly higher price, but if the scrap rate can be reduced, a business case for this gas mixture could be possible.
In addition to the material and process results, there were interesting learnings in terms of the hardware used. To avoid a variation in the oxygen level during the DMLS® process, it is necessary to have a closed loop control to maintain the residual oxygen content within the process gas. The positioning of the oxygen sensors is important and thanks to this study, the optimal location close to the platform was ascertained.
EOS and Linde will continue to work closely together to develop a controllable shielding gas atmosphere for both existing and upcoming DMLS® systems like the EOS M290.