Continuous Wave Fibre Laser Drilling of High Aspect Ratio Holes in Ni-Based Alloys
Over the last 40 years the laser drilling of metallic alloys has been achieved by pulsed beams through percussion, trepanning (cutting), and helical processes. This paper reports a new laser drilling technique based on a continuous wave (CW) 1 kW single mode fibre laser. Through-holes of 160.0 to 190.0 mm diameters were drilled in 2 mm thick Ni-based superalloy plates. Zero tapered holes with a small recast layer (<15.0 mm) free from microcracks were demonstrated for drilling CMSX-4 single crystal and Haynes 230 superalloys. The drilling time was less than 20 ms per hole. A discussion is made on the drilling mechanism involved in the CW fibre laser drilling in comparison with pulsed beam drilling supported by computational fluid dynamic (CFD) modelling.
Keywords: Fibre laser, nickel alloy, Ni-based alloy, CMSX-4 single crystal superalloy, Haynes 230 superalloy, laser drilling, continuous wave (CW), taper, recast layer, computational fluid dynamic (CFD) modelling, aerospace