Analysis of Hole Characteristics in Mechanical Micro-drilling of CFRP-Ti6AI4V Stack Composite

In the present research study, the objective was to estimate three critical output parameters for the mechanical micro-drilling process of CFRP-Ti6Al4V stack composite, which were radial overcut, delamination factor, and hole taper, using response surface methodology (RSM). This study considered spindle speed, feed rate, and MQL flow rate as input parameters and used the central composite design (CCD) method for their experimental design. They conducted 20 experiments and created a mathematical model to determine the relationship between input machining parameters and output parameters. The ANOVA analysis was conducted at a 5% significance level to identify significant coefficients. The study results revealed that spindle speed had a significant impact on all three output parameters. The predicted outcomes from the developed models were consistent with the expected values. The experimental results demonstrated a moderate fit, with a coefficient of determination of 0.7482 for radial overcut, 0.7204 for delamination factor, and 0.8423 for hole taper. These findings have practical implications for optimizing the mechanical micro-drilling process for CFRP-Ti6Al4V stack composite, resulting in better hole quality in micro-drilling applications.