Laser Percussion Drilled Blind Hole Depth and Diameter Monitoring with Laser-induced Plasma Detection
Y-J. Chang, C-S. Wang, H-Y. Chang and Y-H. Hsiao
Laser drilling is not only widely used in a variety of materials but also commonly applied to diverse industrial fields. Due to the fast processing speed, the monitoring of the laser drilling process has always been a challenge. Some studies have been conducted to measure the signal of laser-induced plasma in the laser percussion drilling process by applying an external electric field to monitor the laser percussion drilling process in real-time. Using the laser-induced plasma signal for monitoring purposes, the relationship model between the measured plasma signal and the hole size achieved with laser percussion drilling has not been established. Once the relationship model is determined, the plasma signal can be used to predict the size of the laser drilled hole dimensions in real-time, and further realize a closed-loop control of the laser processing for a higher control technology. For this reason, we conducted a series of laser percussion drilling experiments with a fibre laser on 304 stainless steel and established a model by curve fitting with the laser percussion drilled hole sizes and the plasma signals in various laser processing parameters.
Keywords: Laser drilling, 304 stainless steel, laser percussion drilling, plasma, detection, electric field, curve fitting