Improving the Mechanical Strength of Dental Applications and Lattice Structures SLM Processed

Abstract

To manufacture custom medical parts or scaffolds with reduced defects and high mechanical characteristics, new research on optimizing the selective laser melting (SLM) parameters are needed. In this work, a biocompatible powder, 316L stainless steel, is characterized to understand the particle size, distribution, shape and flowability. Examination revealed that the 316L particles are smooth, nearly spherical, their mean diameter is 39.09 μm and just 10% of them hold a diameter less than 21.18 μm. SLM parameters under consideration include laser power up to 200 W, 250–1500 mm/s scanning speed, 80 μm hatch spacing, 35 μm layer thickness and a preheated platform. The effect of these on processability is evaluated. More than 100 samples are SLM-manufactured with different process parameters. The tensile results show that is possible to raise the ultimate tensile strength up to 840 MPa, adapting the SLM parameters for a stable processability, avoiding the technological defects caused by residual stress. Correlating with other recent studies on SLM technology, the tensile strength is 20% improved. To validate the SLM parameters and conditions established, complex bioengineering applications such as dental bridges and macro-porous grafts are SLM-processed, demonstrating the potential to manufacture medical products with increased mechanical resistance made of 316L.

Physical–Mechanical Characteristics and Microstructure of Ti6Al7Nb Lattice Structures Manufactured by Selective Laser Melting

“…On the other hand, some of the particles which are near to the strut surface are caused by the balling phenomenon. This unfavorable phenomenon results in breaking up the liquid scan track during the laser irradiation, and it produces particles in spherical shapes [ 46 , 66 ]. Due to these two causes, the SLM struts are micro-rough; this finding has also been confirmed in the literature [ 8 , 10 , 25 , 37 ].…”

“…Regarding the microstructural defects, some gas voids with 10–30 µm dimension can be observed in Figure 5 b, Figure 6 b, and Figure 7 b (purple arrows). These spherical micro-voids are induced by gas entrapment [ 46 ]. The recorded micro-cracks are irregularly distributed in the strut structure, having different lengths ( Figure 7 b, blue arrows).…”

“…To limit these issues, adapted process parameters are needed for a stable fabrication of lattice structures made of Ti6Al7Nb. After examining the literature recommendations regarding the SLM process parameters which could be proper for Ti6Al7Nb powder [ 20 , 35 ], and based on our previous studies [ 42 , 44 , 45 , 46 ], we programmed and tested more than 10 laser parameters. To have an efficient production speed, the layer thickness was maintained constant at 50 µm.…”

The Influence of Hybrid Surface Modification on the Selected Properties of CP Titanium Grade II Manufactured by Selective Laser Melting

“…The choice of this material was motivated by the fact that it is the main material used for dental implants [28][29][30] and it is an attractive basis for lowering the Young's modulus [1][2][3][4][5][6][7]. Moreover, the dental implantology is also an area of potential application of using selective laser melting (SLM) technology [31,32]. The use of titanium allows also assessing the effect of treatment on the dominant component of its alloys, without an impact resulting from other components.…”

Bioactive Tetracalcium Phosphate Scaffolds Fabricated by Selective Laser Sintering for Bone Regeneration Applications

“…Selective laser sintering (SLS) is a leading technology, which is based on the rapid prototyping method of layer-by-layer manufacturing technology, and can overcome the abovementioned problems encountered in conventional methods [14,15]. This layered manufacturing technique allows the fabrication of porous scaffolds, with precise control of pore size, interconnectivity, porosity, and external geometries [16,17]. Williams et al fabricated 3D polycaprolactone (PCL) scaffolds with high porosity and interconnected pores via SLS.…”