Comparative analysis of tool wear in micro-milling of wrought and selective laser melted Ti6Al4V

Abstract

The parts produced by additive manufacturing (AM) are not usually appropriate for direct applications and require several post-processing operations. Micro-milling, as a most common post-processing operation in micromachining, is performed considering selective laser melted (SLM) Ti6Al4V as the workpiece under dry condition. The experiments are conducted considering a constant cutting speed and axial depth using a TiAlSiN-coated tungsten carbide end mill of Ø300 μm. It employs two different feed rates considering the size effect imposed by the edge radius of the micro end mill. The micro-milling performances for the SLM Ti6Al4V are compared with the performance for wrought Ti6Al4V. The outcomes, such as tool wear and surface characteristics, are examined for both the materials. Equiaxed grains, exhibiting higher ductile nature of wrought Ti6Al4V, produces adhesive tool wear, BUE formation and poor surface topography at both feed rates. Alternatively, the lamella microstructure of SLM Ti6Al4V, exhibiting relatively high hardness, produces less adhesive tool wear and BUE formation; instead, it generates more abrasion of the tool and hence increases the surface roughness. Quantitatively, the cutting-edge radius enlarges by 18–37% and 10–34% for wrought and SLM Ti6Al4V, respectively. Moreover, the SLM Ti6Al4V shows an 8–10.6% lower average surface roughness value than wrought Ti6Al4V.