Comparative performance evaluation between uncoated and TiAlN + AlCrN coated carbide tools in hard turning of AISI H11 steel

Abstract

Cutting tools, such as ceramic, cubic boron nitride, and polycrystalline diamond, are normally preferred to machine hardened hot work steel materials which are exclusively demanded in mould and die-making industries. However, such tool materials are very costly. If carbide tools with proper coatings will be used within a particular machining range, comparative tool life can be achieved with lesser cost in hard machining. The present experimental work is based on the comparative assessment among new generation TiAlN + AlCrN coated and traditional uncoated carbide tools concerning tool life, tool flank wear, cutting temperature, cutting force, and surface integrity in dry hard turning of AISI H11 steel. The experiments with 16 trials are performed according to the L16orthogonal array by considering various machining parameters that include cutting speed, depth of cut, and feed. At last, with the measured tool life and as per Gilbert's economic approach, distinctive cost analysis has been implemented to demonstrate the cost-effectiveness of coated carbide tools in hard turning. From the experimental results, a promising machining performance is noticed for TiAlN + AlCrN coated carbide inserts in terms of all machining attributes compared to uncoated carbide inserts due to superior wear resistance, and surface hardness as well as strength of coating material. In summary, the multilayer TiAlN + AlCrN coated carbide tool offers significant cost savings (Rs. 12.82 in Indian currency), with a 9% reduction in production costs in comparison with hard turning via. uncoated insert (Rs. 14).