Energy modeling and eco impact evaluation in direct metal laser sintering hybrid milling

This paper presents an analytical model of energy consumption for Direct metal laser sintering hybrid milling (DMLS-HM) additive manufacturing (AM) of stainless steel 316L. The model is used to quantify energy consumption during production of a defined geometry with DMLS-HM process and compared with energy consumption in electron beam melting (EBM) and conventional machining (CM). The solid-envelope ratio (α) was used to quantify energy consumption and eco impact of the three manufacturing processes on three different geometry models. The Gabi database and other published literature were used to establish energy consumption during primary metal production and material shaping processes. It was found that solid-envelope ratio (α) has more impact on the energy model of the additive processes than on the subtractive machining. On average, the percentage change in α is equal to the percentage change in energy consumed by DMLS-HM and EBM. The CM process had very little average change of 1.5% compared to the major changes in α. The DMLS-HM process showed dominant energy consumption during the part production stage with an average 84% more than EBM and CM processes. However, the CM was dominant in energy consumption during the primary production stage with an average 70% more energy than DMLS-HM and EBM processes. The novel outcomes of this research will contribute to the understanding of basic physics of energy consumption in AM and can be used in setting sustainable manufacturing goals. Moreover, energy consumption in metal AM also influences mechanical properties and microstructure of produced parts, so this work will further enhance prediction of their quality and service life. DMLS-HM is recently being introduced for industrial applications such as mold and tool manufacturing due to its capabilities in building free form and complex shapes that are otherwise challenging to manufacture by conventional methods.