Comparative performance evaluation between HSN 2 -TiAlxN and TiCN coated carbide tools in hard turning of AISI D6 steel

Hardened steels are exclusively in great demand particularly in mould and die making industries. Cutting tools such as ceramic, CBN, PCBN and PCD are normally preferred to machine hard to cut materials but are expensive in terms of cost. The usage of carbide tools with proper coatings within a particular machining range, a comparable tool life can be achieved with lesser cost in hard machining. The present experimental work dealt with a comparative assessment among newly developed TiAlxN and traditional TiCN coated carbide tools in terms of tool life, tool (crater and flank) wear, cutting temperature and surface integrity in dry hard turning of AISI D6 steel. The experiments with 16 trials are performed according to L-16 orthogonal array by considering various machining parameters such as cutting speed, depth of cut and feed. Finally, the measured tool life was considered in the Gilbert's economic approach, to perform a distinctive cost analysis which justified the cost-effectiveness of coated carbide tool in hard turning. Among the tools used, TiAlxN coated carbide tool for hard turning application promises and excellent machinability performances in terms of (i) lower flank and crater wears (ii) longer tool life, (iii) improved surface integrity, (iv) minimum cutting temperature and (v) considerable economic advantages as the production cost is reduced by 6%. The nanostructured TiAlxN coating accomplished by physical vapour deposition (PVD) technique considerably developed lower range of tool wear (VB = 0.053-0.134 mm), produced surface finish (Ra) within 0.35-1.07 mu m, and following the surface quality at par closer to cylindrical grinding because of superior surface hardness, wear resistance, and bonding strength of coating material. TiAlxN coated carbide tool offered significant cost savings (Rs. 82.21 in Indian currency) in production costs in comparison to hard turning via. TiCN (Rs. 87.10) coated insert.