Tool Wear and Surface Integrity Analysis of Machined Heat Treated Selective Laser Melted Ti-6Al-4V

2. Experimental Procedure

Hollow cylindrical samples of wrought and additive manufactured Ti-6Al-4V were used as work materials in this research. A hollow cylindrical specimen of height 60 mm, outer diameter 50 mm and inner diameter 25 mm was fabricated using a SLM 125 metal additive manufacturing machine (as shown in Figure 1). Important process parameters such as meander build style, 0.2 mm laser focus diameter and 425 mm/s laser scan speed were used in fabricating this hollow cylinder. The sample was then heat treated in a vacuum furnace to 730^oC and cooled slowly to 1) relieve the residual stresses and 2) soften and improve the materials ductility. Face turning machining operation was then performed on the material in a Nakumara tome CNC machine. TiAlN+TiN PVD coated rhombic carbide tools with positive rake angle and a tool nose radius of 0.8 mm was used for the machining tests. The designation of the cutting tool used is DNMG 150608-TF.The material was machined at different cutting speeds of 60,120 and 180 m/min using a constant feed rate of 0.1 mm/rev and depth of cut of 0.5 mm respectively. The tool specimens and the machined surface were collected and preserved after specific number of machining passes to study the tool wear and surface integrity. The tool wear and surface characteristics was measured and characterized using optical and scanning electron microscope. The surface roughness was measured using Alicona Infinite Focus 3D optical surface profilometer.