The Influence of Selective Laser Melting (SLM) Process Parameters on In-Vitro Cell Response

Abstract

The use of laser 3D printers is very perspective in the fabrication of solid and porous implants made of various polymers, metals, and its alloys. The Selective Laser Melting (SLM) process, in which consolidated powders are fully melted on each layer, gives the possibility of fabrication personalized implants based on the Computer Aid Design (CAD) model. During SLM fabrication on a 3D printer, depending on the system applied, there is a possibility for setting the amount of energy density (J/mm3) transferred to the consolidated powders, thus controlling its porosity, contact angle and roughness. In this study, we have controlled energy density in a range 8–45 J/mm3 delivered to titanium powder by setting various levels of laser power (25–45 W), exposure time (20–80 µs) and distance between exposure points (20–60 µm). The growing energy density within studied range increased from 63 to 90% and decreased from 31 to 13 µm samples density and Ra parameter, respectively. The surface energy 55–466 mN/m was achieved with contact angles in range 72–128° and 53–105° for water and formamide, respectively. The human mesenchymal stem cells (hMSCs) adhesion after 4 h decreased with increasing energy density delivered during processing within each parameter group. The differences in cells proliferation were clearly seen after a 7-day incubation. We have observed that proliferation was decreasing with increasing density of energy delivered to the samples. This phenomenon was explained by chemical composition of oxide layers affecting surface energy and internal stresses. We have noticed that TiO2, which is the main oxide of raw titanium powder, disintegrated during selective laser melting process and oxygen was transferred into metallic titanium. The typical for 3D printed parts post-processing methods such as chemical polishing in hydrofluoric (HF) or hydrofluoric/nitric (HF/HNO3) acid solutions and thermal treatments were used to restore surface chemistry of raw powders and improve surface.

Comparative Analysis of Mechanical Properties and Metal-Ceramic Bond Strength of Co-Cr Dental Alloy Fabricated by Different Manufacturing Processes

“…The laser could also be the key to harden metals and ceramics [ 14 ]. Furthermore, objects with complex geometries are achievable with a high-dimensional accuracy [ 15 , 16 , 17 , 18 ]. Compared to casting and milling processes, SLM reduces the probability of operator errors, minimizes defects and wastes almost no material since the remaining powder can be used further [ 19 ].…”

Progressive 3D Printing Technology and Its Application in Medical Materials

“…As a specific kind of SLS, DMLS utilizes metal exclusively. Different from sintering techniques, SLM and EBM fully melt powder with laser and electron beam respectively (Wysocki et al, 2018). For the work of electron beam, the powder bed in the EBM printer maintains high working temperature (> 870 K).…”

3D-printing process design of lattice compressor impeller based on residual stress and deformation

“…To predict the mechanical properties (such as deformation and residual stress), shorten the design and production cycle, reduce the production cost of the processed parts, and improve the qualified product rate, it is necessary to apply CAD technology to simulate the production process of metal 3D printing when adding materials to the processed parts (including the metal lattice impeller). Currently, some scholars have carried out a number of experimental studies on the mechanical properties 15,18,[24][25][26] and 3D-printing process [27][28][29][30] of lattice structures. In these studies, some simple geometric structures are taken as the main research objects, and the mechanical properties of these lattice structures and effects of the printing parameters on the mechanical properties of these structures are analyzed.…”