Powder Bed Fusion processes

The production of Ti6Al4V 3D printed samples has been carried out by two Powder Bed Fusion processes.

Electron Beam Melting (EBM) and Selective Laser Melting (SLM) through an ARCAM EBM SYSTEMS MODEL A2 and a EOS M290, respectively. These two techniques are different in terms of dimensional accuracy, surface finishing and internal defects caused by the process itself. The aim of the project is the comparison between the two process to highlights their differences and potentials for the target application: the fabrication of newly designed orthopedic implants. In particular, the building orientation of the printing process in relation to the building plate has been investigated by printing of the samples with four different angles of direction: 0°,15°,30° e 45°. The results about the process parameters on the obtained samples highlighted the differences on the surfaces in terms of morphology (Fig. 1) that has been considered relevant for the modulation of the adhesion mechanism of the selected cells for this project: pre-osteoblasts (bone tissue cells) reported in Fig 2. The evaluation of the cells vitality has been carried out by dedicated assays to identify the levels of cell proliferation at three time points set after 24, 48 and 96h (Fig. 3). The results reported the potential of each sample in relation to the building angle and the chosen production technique. Further characterization on the chemical, metallurgical and roughness of the samples are ongoing such as the evaluation of the mineralization mechanism of the differentiated cells to verify the performance of the 3D printed metal samples in terms of osseointegration, necessary for integrated devices.

Fig. 1: SEM pictures of Ti6Al4V samples surfaces obtained by EBM e SLM at an angle of 0°.
Fig. 2: Fluorescent images of cells nuclei stained with DAPI
on the Ti6Al4V samples surfaces obtained by EBM e SLM.
Fig. 3: Evaluation of the cells viability (ATP assay)
on the Ti6Al4V samples surfaces obtained by EBM e SLM.

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