Statistical Modelling and Optimization of Laser Percussion Microdrilling of Inconel 718 Sheet Using Response Surface Methodology (RSM)

To investigate the influence of fibre laser percussion drilling process parameters on the hole geometric features of Inconel 718 with thickness of 1.0 mm experiments were conducted based on response surface methodology (RSM). Frequency of the laser beam (200 to 400 Hz), duty cycle (30 to 50%), laser power (375 to 425 W) and focal plane position (0.7 to 1.5 mm) were considered as independent variables, while the entrance and exit hole diameters, as well as the hole taper were raised as process outputs. The obtained results indicate that the entrance hole diameter increases as the laser pulse frequency, laser power, duty cycle and focal plane position increase; furthermore, by increasing duty cycle and focal plane position, the hole taper decreases. Minimum hole taper, maximum exit diameter, and minimum entrance diameter were considered as optimization criteria. Verification experiments were carried out in order to analyse the results via software.