EXPERIMENTAL ANALYSIS OF CUTTING PARAMETERS AND THEIR EFFECT ON SURFACE ROUGHNESS IN ADVANCED METHOD OF HARD TURNING USING CBN TOOLS

This study investigates the influence of cutting speed (V) and feed rate (f) on surface roughness average (Ra), total roughness (Rq), and mean depth of roughness (Rz) during Hard Turning (HT) and Surface Defect Machining (SDM) of AISI 4340 steel, hardened to (51 ± 1) HRC. Experiments were conducted using CBN tools using a full factorial design (4² = 16 trials) with a constant depth of cut, as per Response Surface Methodology (RSM). Identical trials were performed for both HT and SDM to enable a comparative study. Results indicate that SDM yields significantly better surface finish, improving Ra by 41.65% compared to HT. ANOVA results support a quadratic model for predicting surface roughness variations. Feed rate emerged as the most influential factor in both machining methods, whereas cutting speed showed minimal impact. Optimization of cutting parameters was achieved to minimize Ra, Rq, and Rz, enhancing surface quality and overall machining efficiency.