Performance analysis of uncoated and coated (TiN-,TiAlN-) carbide drills in drilling graphene-reinforced GF/epoxy nanocomposites: Analytical and experimental study

The present study aims to investigate the performance of conventional uncoated and coated (TiN, TiAlN) solid carbide drill tools in drilling bi-directional graphene-reinforced (2 wt.%) glass fiber (GF)/epoxy polymer nanocomposite laminate with two distinct lamination schemes ([0/90]_12S and [0/90/±45]_6S). Performance measures included thrust force, torque, tool flank wear, peak acoustic emission, root mean square (RMS) of acoustic energy, and average surface roughness. Moreover, the delamination that occurs beyond the critical value of thrust force (computed analytically) has also been addressed. Optimized drilling parameters were used for experimentation to minimize thrust force and torque simultaneously. Both TiN and TiAlN-coated carbide drills outperformed uncoated carbide drills for fewer holes (around 25 for TiN and about 40 for TiAlN), but their performance deteriorated with more holes due to coating chipping or peeling from the original tool material. The (0/90 ± 45)_6S graphene-reinforced layup showed less tool wear, deterioration, and acoustic emission energy compared to the (0/90)_12S neat layup. TiAlN-coated drills exhibited the smallest wear on the flank face followed by TiN-coated and uncoated carbide drills. Moreover, the smoothest cut surface throughout the 300 holes drilled, averaging 1.5 µm to 1.8 µm in surface roughness, was observed with the TiAlN-coated drill. Therefore, the TiAlN-coated drill is recommended for drilling a larger number of holes due to its reduced tool wear, smoother cut surfaces, and better form accuracy with minimal delamination.