Experimental investigation on micromilling machining of ti-6al-4v titanium alloy additively manufactured by selective laser melting (SLM).

• Autor(a) principal: Gonçalves, Maria Clara Coimbra
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/3/3151/tde-07042022-152934/
• topic: Additive manufacturing; FSL; Ligas de titânio; Manufatura aditiva; Microfresamento; Micromilling; PBF; Processos de fabricação; Ti-6Al-4V; Ti-6Al-4V; Titanium alloys

Increasingly, small size components are being used by many fields which use miniaturized products as working tools, highlighting the medical and dental industries. Both micromachining and additive manufacturing processes can be separately applied to obtain these products, but combining both processes show great potential for reducing manufacturing time and costs. In this context, additive manufacturing processes, such as Powder Bed Fusion (PBF), have gained attention in producing near-net-shape components due to their lower material consumption and ability to generate complex geometries. However, parts manufactured by this process present two main characteristics: periodic surface and anisotropy related to their printing direction. Therefore, machining processes such as micromilling need to be done on the parts in order to achieve the desired dimensional, geometric and/or roughness tolerances. However, the study of micromilling process in printed parts is recent and its machinability is poorly known. Thus, this work aims to make a comparison between the results of the micromilling process of conventional and printed parts by Selective Laser Melting, with and without heat treatment. The material analyzed was the titanium alloy Ti-6Al-4V, which is one of the most applied titanium alloys in aerospace, aeronautical, medical and dental sectors. For this reason, micromilling tests were carried out, varying the machining parameters, to analyze the results of machining forces, surface roughness, burr formation and residual stresses. In addition, a comparison was made with the results made on a micro milling machine with a mini dynamometer and a conventional CNC machine. With the obtained results, it was observed that, for the set of parameters used, no significant difference was observed on machining forces, surface roughness and burr formation for micromilling samples of commercial Ti6Al4V and additively manufactured. In addition, the machining force results collected in a conventional CNC were higher due to the robustness of this system. It is also noteworthy that, for the experiments on this work, the cutting speed was the most influential parameter on the cutting forces and the feed influenced the feed forces the most. The best surface roughness results were obtained for the smallest micromills and at high speeds. Also, burr formation presented a correlation with feed forces results. Furthermore, adhesion of material on the cutting edge of the tool was observed in the experiments. Therefore, the obtained results corroborate to the improvement of the micromachining process in materials with low machinability. Thereby, aiming to optimize this process and to produce high quality components.