Tool life performances, wear mechanisms and surface roughness characteristics when turning austenised and quenched AISI 52100 bearing steel with ceramics and CBN/TiC cutting tools

摘要

Tool life performances and wear mechanisms of various cutting tools such as mixed alumina ceramic (KY1615), coated ceramic (KY4400) and cubic boron nitride (CBN/TiC) are investigated experimentally under different cutting conditions in turning austenised and quenched AISI 52100 steels. Worn surfaces of the cutting tools are examined by scanning electron microscope (SEM) to find out the effective mechanism of wear. The surface roughness values are measured with surface profilometer and which cutting tool will provide a lower surface roughness values are investigated in the machining of hardened bearing steel AISI 52100. The experimental results showed that tool life decreased with increasing speed for all cutting tools. The longer tool life is obtained for the CBN/TiC cutting tool when machining the hardened AISI 52100 steel. However, the difference among the tool lives decreased considerably with decreasing the cutting speed. In addition, it is observed that the major wear form of the tools is the smooth flank wear for the CBN/TiC tool. However, crater and flank wear are observed for the KY1615 cutting tool while tool nose deformation is observed for the KY4400 cutting tool when machining the hardened steels. CBN/TiC and KY615 tool produced better surface roughness values of R_a than the KY4400 tools in all experimental conditions. On the surface roughness, low and medium cutting speed does not show a significant effect for all tools. But, R_a surface roughness values decreased with the highest cutting speed value. On the other hand; surface roughness value of R_a improved in the lowest depth of cut for all tools.