Optimization of cutting parameters in near dry machining of hardened steel

Abstract

Machining of pre-hardened steel materials, known as hard turning, is gaining more and more attention recently because it offers numerous advantages over traditional grinding in some applications. In addition it differs from conventional turning process since it possesses some special behaviors such as chip breakability and micro structural alteration at the machined surfaces. Typically no cutting fluid is applied during hard turning in order to minimize both cutting forces and environmental impacts. Near dry machining which refers to the use of small amount of cutting fluid addresses itself as a viable alternative for hard machining with respect to tool wear, heat dissertation, cutting force generation and machined surface quality. The present research work is divided into two parts. First of all there is an experimental analysis of the effects of minimum quantity lubrication on cutting zone temperature, main cutting force, chip thickness ratio, tool wear and surface quality of the machined part while turning hardened steel (56 HRC) material with coated carbide insert. The results indicated that the application of near dry machining technique significantly helps to obtain better result in compare to dry condition. The other part of the research work is concentrated to the optimization of cutting parameters (cutting speed, feed rate and depth of cut) while turning hardened medium carbon steel by coated carbide insert under near dry machining condition. Optimization was done using genetic algorithm. The objective function of the optimization process was to determine the cutting parameter that minimizes surface roughness under certain constraints. Statistical models using multiple regression analysis under Response Surface Methodology (RSM) have been developed to establish the objective function and also the constraints for solving the problem. The developed models satisfactorily validate its accuracy by drawing desirable experimental results.