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.
