Original article Experimental evaluation of selective laser melting process for optimized lattice structures G De Pasquale 1 , F Luceri 1 and M Riccio 2 Abstract Lattice structures fabricated with micromelting of metal powders are promising solutions for lightweight applications. Additive manufacturing processes as selective laser melting are largely used to build bulk components, but the influence of laser settings on lattice struts morphology is not jet fully investigated. Previous studies demonstrate the effect of laser speed and layers thickness on the material density and lattice struts dimensions. In this paper, the effects of the laser volume energy density associated with the process setup parameters are analyzed in relation to the dimensional accuracy of lattice struts. The statistical approach based on design of experiments used in this paper allows getting appreciable reduction of the average errors of struts dimensions (from 48% to 16% and from 22% to 7% in horizontal and vertical orientations, respectively). Keywords Lattice structures, cellular materials, additive manufacturing, lightweight design, design for additive, selective laser melt- ing, Ti–6Al–4V, laser volume energy density Date received: 4 April 2018; accepted: 2 September 2018 Introduction The interest in cellular and lattice materials has been increased in the last years due to the need of light- weight structures in many fields. Furthermore, the rapid development of additive manufacturing (AM) technologies is providing innovative and reliable solu- tions for stable and repeatable fabrication processes, especially about powders micromelting. 1–5 Selective laser melting (SLM) is applied to the fabrication of metal lattice structures because of high flexibility and suitability for building complex geometries and sus- pended parts. 6–10 SLM is based on the progressive melting of powder layers in vertical direction under inert atmosphere. 11,12 Although different materials are suitable for build- ing lattice structures by SLM process, such as alumi- num alloys 13,14 and stainless steel, 15 titanium alloys (e.g. Ti–6Al–4V) are the most diffused because of their corrosion resistance, high strength, and biocom- patibility. 16–23 Several AM applications with titanium alloys are present in medical implants and pros- theses, 24–26 aeronautic, spatial, 27,28 and automotive 29 devices. Several contributions have been provided to design and optimization of lattices by numerical and homogenization methods 30–39 and by analytic models. 40–42 Similarly, the structural strength of lattices has been largely evaluated by experiments on multi-cells specimens under compressive or shear loads. 43–56 At the same time, the study of SLM fabrication process parameters in relation to the struts morph- ology is not deeply investigated. In particular, the effects of laser settings and volume energy density (VED) on the dimensional tolerances of struts and on material density require additional systematic ana- lyses. The reasons for this lack of information are linked to the high cost of SLM machines and limita- tions to industrial data disclosure. Furthermore, the application of stringent requirements of repeatability and qualification of processes has been started only recently, especially for the most challenging applica- tions (aeronautics, spatial engineering, biomedicine, etc.). Proc IMechE Part E: J Process Mechanical Engineering 0(0) 1–13 ! IMechE 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0954408918803194 journals.sagepub.com/home/pie 1 Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Torino, Italy 2 BeamIT, Fornovo di Taro, Parma, Italy Corresponding author: G De Pasquale, Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Corso Duca degli Abruzzi, Torino 24-10129, Italy. Email: giorgio.depasquale@polito.it