Taguchi analysis of drilling quality associated with core drill in drilling of composite material

The thrust force and surface roughness of core drill with drill parameters (grit size of diamond, thickness, feed rate and spindle speed) in drilling carbon fiber reinforced plastic (CFRP) laminate was experimentally investigated in this study. A L-27 (3(13)) orthogonal array and signal-to-noise (S/N) were employed to analyze the effect of drill parameters. Using Taguchi method for design of a robust experiment, the interactions among factors are also investigated. The experimental results indicate that thickness and feed rate are recognized to make the most significant contribution to the overall performance. For thrust force, the drilling conditions were A(1)B(1)C(1)D(2), (i.e., grit size of diamond=#60, thickness=1.0 mm, feed rate=0.012 mm/rev, and spindle speed=950 rpm). For surface roughness, the drilling conditions were A(1)B(1)C(1)D(3), (i.e., grit size of diamond=#60, thickness=1.0 mm, feed rate=0.012 mm/rev, and spindle speed=1150 rpm). The correlation was obtained by multi-variable nonlinear regression and compared with the experimental results. The confirmation tests demonstrated a feasible and an effective method for the evaluation of drilling-induced thrust force and surface roughness (errors within 10%) in drilling of composite material.