Surface roughness model for machining mild steel with coated carbide tool

This paper presents a study of the development of a surface roughness model for turning of mild steel with coated carbide tools. The model is developed in terms of cutting speed, feed rate and depth of cut, using response surface methodology. Machining tests were carried out with TiN-coated carbide cutting tools under various cutting conditions. First-order and second-order model predicting equations for surface roughness have been established by using the experimental data. The established equation shows that the feed rate was main influencing factor on the surface roughness. It increased with increasing the feed rate but decreased with increasing the cutting speed and the depth of cut, respectively. In addition, analysis of variance for the second-order model shows that the interaction terms and the square terms are statistically insignificant. The predicted surface roughness of the samples has been found to lie close to that of the experimentally observed ones with 95% confident intervals. Moreover, it is seen that the first-order effect of feed rate and cutting speed is significant while depth of cut is insignificant.