Metal Additive Manufacturing Conference 2018

Additive manufacturing technologies enable the efficient production of metal parts with high geometrical complexity. The highest degree of design freedom offer powder bed based methods like selective laser melting (SLM) and therefore, they are capable of fabricating components with integrated lattice structures [1]. This implementation of lattice structures can significantly enhance the parts functionality concerning lightweight design, bone-ingrowth features or catalytic properties [2,3,4]. Depending on the required load bearing efficiency and desired stiffness, the production of very thin struts and small unit cells can be necessary. However, micro lattices with defined strut diameters below 300 micron cannot be produced by industrial SLM machines by default. To manufacture thin micro lattice structures matching the CAD design, parameter studies have to be performed in advance and design rules have to be followed. In this work, the preliminary stages of micro lattice fabrication on a commercial EOS M280 machine are presented and the manufacturability of lattice strut elements for varying inclination angle and diameter is described. Based on the identified limits, CAD design rules are given and the corresponding SLM compatible lattices are manufactured with optimized parameters. The morphology and the relative densities of the fabricated lattice structures are then compared to the CAD data and the mechanical properties are measured by compression tests. [1] Yap, C. Y. et al. Review of selective laser melting: Materials and applications. Applied Physics Reviews 2, 2015. [2] Yan, Chunze et al. Advanced lightweight 316L stainless steel cellular lattice structures fabricated via selective laser melting. Materials and Design 55, 2014, pp. 533-541. [3] Tan, X. P. et al. Metallic powder-bed based 3D printing of cellular scaffolds for orthopaedic implants: A state-of-the-art review on manufacturing, topological design, mechanical properties and biocompatibility. Materials Science and Engineering C, Volume 76, 2017, pp. 1328-1343. [4] Yadroitsev, I. et al. Manufacturing of fine-structured 3D porous filter elements by selective laser melting. Applied surface Science 255, 2009, pp. 5512-5527.