An investigation into the variation in porosity of a direct metal laser sintered artifact manufactured with the EOSINT M250 machine system using direct metal 20 powder

Abstract

Direct Metal Laser Sintering (DMLS) is a rapid prototyping technique that allows for direct and rapid manufacturing of complex components. DMLS is however an intricate process and the quality of the final product is influenced by multiple manufacturing parameters (or DMLS settings) and powder characteristics. The effect which each of these manufacturing parameters and powder characteristics has on the final parts is not well understood and the success of process manufacturing mainly relies on empirical knowledge. Consequently high dimensional deformation and relatively poor mechanical properties are obtained in many DMLS products, in particular in Direct Metal 20 copper-based laser sintered parts produced with an EOSINT M250 system in use at the Centre for Rapid Prototyping at the Central University of Technology. A need therefore existed to systematically examine the effect of process parameters on the density of final parts in order to determine the most appropriate manufacturing parameters for specific applications of copper-based laser sintered parts at this institution. This paper summarises the effect of different process parameters and sintering strategies on the quality of Direct Metal 20 laser sintered parts produced with an EOSINT M250 Xtended laser sintering machine from powder consisting of Ni5Cu, Cu15Sn – Cu5Sn and Cu8P – Cu2P material grains – where quality in this paper is measured as porosity which was indirectly measured via Image Analysis. The effects of three different geometric sintering strategies currently in standard use namely Solid Skin, Skin Stripes and Skin Chess were examined. This paper reports on porosity of parts sintered to these strategies by liquid phase sintering, in order to find final appropriate associated process parameters. Porosities as low as 7% only were obtained in parts sintered according to the Skin Stripes sintering strategy