Statistical Model for Surface Roughness in Hard Turning of AISI D3 Steel

In the present experimental work, the effects of cutting speed, feed rate and depth of cut on surface roughness are investigated in hard turning of AISI D3 steel. AISI D3 steel is hardened to 62 HRC and is machined using a mixed ceramic tool. Mathematical models for surface roughness are developed using the Response Surface Methodology (RSM). Central Composite Design (CCD) is applied as an experimental design. Al2O3/TiC mixed ceramic tool with corner radius of 0.8 mm is employed to accomplish 20 tests with six centre points. The range of each parameter is set at three different levels, namely low, medium and high. The main effects of the factors and their interactions were considered in the present study using Analysis of variance (ANOVA). Various graphs and plots are drawn to evaluate the influence of the process parameters on surface roughness. Feed rate is the most influencing factor on surface roughness. Results revealed that the use of lower feed, lower depth of cut and higher cutting speed, while hard turning of AISI D3 hardened steel, ensures a better surface roughness.