Laser drilling is one of the processing approaches in aerospace industry. However, drilling with ms laser is unstable since the drilled hole is easy to be blocked by re-solidified molten material. To solve this problem, two different pulsed lasers (millisecond and nanosecond) are used in our experiments. The shock wave produced by the ns laser is introduced to increase the migration mass. With the help of shock wave, the depth and quality of the hole get higher. The influences of the interval time, the ms laser energy and the laser pulse duration time on the quality of drilled holes are also discussed. The results show that the hole is deep and clean if the ns laser is added shortly after the beginning of ms laser. The ms laser energy and the laser duration time determine the depth of the hole.
Methods for the machining of metals based on the use of ultra-short pulsed laser radiation continue to gain importance in
industrial production technology. Theoretical considerations and experimental studies on laser drilling of steel are
discussed. The applicability of geometrical optics to calculate the absorbed energy distribution inside small blind holes is
investigated theoretically. A model for melt transport during ultra-short pulsed drilling is proposed and verified
experimentally. It confirms that helical drilling is advantageous for machining burr-free holes.