Investigation of hole quality in drilled Ti/CFRP/Ti laminates using CO2 laser

The machinability of titanium (Ti) and carbon fiber reinforced plastic (CFRP) (Ti/CFRP/Ti) laminates using CO2 laser is presented in this work. The effect of line energy and laser frequency on output responses such as heat affected zone (HAZ), taper angle (TA), metal composite interface (MCI) damage, surface roughness, dross height, and circularity were investigated. Line energy - the most influential parameter - demonstrated a threshold behavior; no drilling was observed below a certain line energy. Scanning acoustic microscopy (SAM), scanning electron microscopy (SEM), micro-computed tomography (mu-CT), and other imaging techniques were used to establish a correlation between laser parameters and CO2 laser machined damage in Ti/CFRP/Ti laminates. The results show that using a higher frequency and lower line energy can significantly improve the hole quality. However, dross free holes with minimum taper can be obtained using higher line energy.