Optimization of Surface Roughness in Hard Turning of AISI 4340 Steel using Coated Carbide Inserts

The use of multilayer coated carbide tool in hard turning has several advantages over grinding process such as; reduction of processing costs, increased productivity, short cycle time, compatible surface roughness and less enviornment problems without the use of cutting fluid. In the present study, an attempt has been made to evaluate the performance of multilayer coated carbide inserts during dry turning of hardened AISI 4340 steel (47 HRC). The effect of machining parameters (depth of cut, feed and cutting speed) on surface roughness (Ra) was investigated by applying ANOVA. The experiments were planned based on Taguchi’s L27 Orthogonal array design. Results showed that surface roughness (Ra) mainly influenced by feed and cutting speed, whereas depth of cut exhibits neglegible influence on surface roughness. The experimental data were further anlyzed to predict the optimal range of surface roughness (Ra). Finally a second order regression model was developed to find out the relationship between the machining parameters and surface roughness.