High Speed Laser Micro Drilling for Aerospace Applications

To realize a reduced fuel consumption of civil jet transport aircrafts, hybrid laminar flow control (HLFC) is a key technology in aerospace industry. For drag reduction caused by boundary layer suction, small holes at the leading edges of the aircraft wings and tail planes are needed. Much effort has been spend in drilling of small holes into different materials. Nevertheless, the economically drilling of small holes in the range of 50 to 100 μm in diameter on large areas is up to date crucial. Apart from processing time this is also due to the demand of close tolerances in case of suction holes. Additionally, minimization of the thermal distortion when drilling large areas gets more challenging. This paper deals with the transfer of the laser drilling process to an adequate system technology for the fabrication of large suction inserts using a short pulsed fiber laser with a power of 200 W at a pulse repetition rate of 200 kHz. The laser combined with a galvanic scanner and a plane field optic leads to a precise and fast drilling over an area of 100 mm x 100 mm. Using a precise stage several of these drilling fields can be placed side by side to machine the complete panel area. The amount of drilled through-going holes and their roundness as well as the distortion of the panel is influenced by the applied drilling sequence and energy input. As a result, round micro holes down to 30 μm in diameter can be produced with a drilling rate of more than 400 holes per second in 0.8 mm thick titanium sheets.