Cost-effective way of hard turning with newly developed HSN2-coated tool

EN-31 (AISI 52100, hardness 55 HRC) is one of the difficult-to-cut steel alloys and it is commonly used in shafts and bearings. Nowadays, it is becoming a challenge to the cutting tool material for economical machining of extremely tough and hard steels. In general, CBN and PCBN tools are used for machining hardened steel. However, machining cost using these tools becomes higher due to high tool cost. For this purpose, carbide tool using selective coatings is the best substitute having comparable tool life, while its cost is approximately one-tenth of CBN tool. In this work, the newly developed second-generation TiAlxN super nitride (i.e., HSN²) is selected for PVD coating on carbide tool insert and further characterized using thermogravimetric analysis and differential scanning calorimetry for oxidation and thermal stability at high temperature. Later, HSN²-coated carbide inserts are successfully tested for their sustainability to expected tool life for turning of AISI 52100 steel. In the present study, forces, surface finish, and tool wear are used as a measure to appraise the performance of hard turning process. Experimentally, it is found that speed, feed rate, and depth of cut have considerable impact on forces, insert wear, and surface roughness of the machined surface.