Direct Metal Laser Sintering Strategies for Fabrication of Finer Resolution Cellular Structures

Abstract

Direct Metal Laser Sintering (DMLS) is an additive manufacturing technology that is capable of fabricating net-shape intricate metallic designs such as cellular structures with tailored mechanical properties. Ideally, these cellular structures replicate the human cancellous bone structure for proper bone tissue engineering applications. In this study, we present novel laser scanning strategies and their associated DMLS processing parameters to fabricate finer resolution Ti-6Al-4V cellular structures toward mimicking human cancellous bone resolution and improved mechanical performance. To this end, three DMLS scanning strategies with various laser power and scanning speed were defined to fabricate diamond and dodecahedron unit cells with four different cell sizes. With the constant laser spot size of 80μm, average powder size of 34μm, and layer thickness of 30μm for all the DMLS processes, the finest achieved resolution for the struts of the cellular structures are reported as 120μm in this study. Furthermore, correlations between DMLS processing parameters/scanning strategies with geometry, porosity, density, and mechanical performance of the cellular structures were comprehensively investigated and discussed. In conclusion, the porosity and mechanical properties of several fabricated dodecahedron cellular structures and human cancellous bone demonstrate significant similarities, e.g., a porosity of 72.6-87.4 %, compressive strength of 0.1-30 MPa, and elastic modulus of 0.01-3 GPa.