Inclined laser drilling in glass fiber reinforced plastic using Nd: YAG laser

The adoption of glass fiber reinforced plastics (GFRP) for making components of robots, microelectronics devices, and wind turbine requires fabrication of inclined holes in GFRP. This study investigate the use of millisecond (ms) pulsed infrared (IR) Nd:YAG laser to create geometrically accurate inclined hole in GFRP using multi pulse laser drilling technique. Parametric study to analyze the effect of laser peak power, pulse width, gas pressure, thickness, angle of incidence on output response of hole circularity at top (HCT), hole circularity at bottom (HCB), and hole taper (HT) have been performed using the Box–Behnken design (BBD) approach of response surface methodology (RSM). Multiobjective optimization of laser percussion inclined hole drilling (LPIHD) has been performed using the integrated approach of grey relational analysis (GRA) and principal components analysis (PCA), to identify the optimum input parameters. Furthermore, scanning electron microscope (SEM) analysis of holes drilled at non-optimized and optimized parameters has been compared. Study reveals that interaction effect of thickness and current has major effect on both HCT and HCB whereas thickness and angle of incidence has significant effect on HT. GRA-PCA optimization increases HCT, HCB by 63.38% and 29.07%, respectively, and reduces HT by 92.10 %.