Millisecond fibre laser trepanning drilling of angular holes

This paper aims to investigate the basic characteristics of millisecond (ms) pulsed fibre laser drilling of 0.8 mm diameter angular holes (30 degrees to the surface) in a 2 mm thick aerospace nickel superalloy (resultant hole length of 4mm). Experiments have been conducted to understand the influence of various process parameters on the hole quality, including gas pressure, nozzle-workpiece distance, laser beam focus position, trepanning speed, number of trepanning orbits, pulse energy, pulse duration and pulse frequency. The results suggest that high quality and high productivity can be achieved with millisecond fibre laser drilling, especially when compared to traditional Nd:YAG laser drilling. A new trepanning drilling method for achieving high-quality laser drilling was proposed and evaluated.