Investigation of surface roughness and burr formation in micromilling processes laser polishing on selective laser melted Ti6Al4V

This study aims to increase the microhardness of Ti-6Al-4 V produced by laser polishing (LP) with selective laser melting (SLM), to make micromachinability with optimum parameters and to minimize surface roughness. LP process has started to attract great industrial interest today due to the significant increase in surface quality. In addition, the processing of small geometry channels, requiring precision and high surface quality, further increases the importance of micromilling. In this experimental study, the surface morphology, microhardness and micromachinability of Ti-6Al-4 V material produced by SLM were investigated before and after LP. The aim is to investigate the increase in microhardness, surface roughness, and burr amount with 3 different spindle speeds (4000-6000-8000), 4 different feed rates (2-4-6-9), and 2 different depths of cut used as micromilling parameters. When the SLM material was compared to the LP material, the hardness value increased by approximately 27%. It was observed that there was a 400% improvement in surface roughness values (Sa). When viewed with three-dimensional surface topography, it is seen that the cutting marks are more prominent in the material made with LP. Surface roughness values are inversely proportional to cutting speed and directly proportional to feed rate. While materials with high hardness should have lower surface quality in machined areas, Sa values are lower in LP areas. In addition, the difference between the surface roughness values is maximum for both SLM and LP material at the same depths of cut. These findings are aimed to determine the machinability parameters during the manufacturing of materials used especially in the aviation, defense, medical, and automotive industries.