Surface roughness and dimensional accuracy of titanium overhanging thin-walls via laser powder bed fusion
Josilainne Marcelino Dias, Michael Gasik, F. Bartolomeu, F.S. Silva, G. Miranda
Abstract
Laser Powder Bed Fusion offers a promising solution for enabling customized products such as implants with more precision and efficiency. Over 10% of titanium implants for joint replacement cause bone destruction due to incompatibility in mechanical design and improper surface matching. The strategy to overcome these issues involves developing specific surface features, such as overhanging walls, to enhance the bone-implant interface. Such features often require support-free fabrication due to the risk of compromising the integrity of thin-walled features during supports removal. Hence manufacturing of titanium overhanging thin-walls, such a critical element in implants, with proper topology and precision requires knowledge of the correct strategy and processing parameters. However, a critical gap remains in the Laser Powder Bed Fusion production and surface characterization of these structures. The purpose of this study is the evaluation of the feasibility of producing unsupported inclined thin-walls using this additive manufacturing technology and assessing the associated surface quality and topology. Here overhanging thin-walls were successfully manufactured with angles closely matching the references (30°, 45°, 60°, 75°, and 90°). Dimensional accuracy and roughness of the walls were assessed for both upskin and downskin surfaces. Higher thicknesses than in designed version were observed for all groups, particularly elevated for 30° overhanging angle, also showing the highest roughness for both upskin and downskin sides. Despite the larger thickness, overhanging angles the 45° and 60° led to the lowest roughness values. • Measured angles closely aligned with expected values. • Total thickness obtained higher than CAD (200 μm) ranging from 430 to 526 μm. • Powder agglomeration depends on inclination with opposite trend on up and downskin. • Lower surface roughness values for all upskin comparing to downskin. • Highest surface roughness at 30° (Sa = 25 μm); lowest at 45° and 60° (Sa = 15 μm).