Green Laser Drilling Assisted with Jet Electrochemical Machining of Nickel-Based Superalloy

Laser drilling is extensively used in the aerospace and aircraft industries. The most important application is the drilling of fine cooling holes in aero turbine engine components such as nozzle guide vanes and blades. However, laser-drilled holes are typically associated with a number of inherent defects such as recast layer and spatter. In order to solve these problems, a novel hybrid process of laser drilling assisted with jet electrochemical machining (JECM-LD) has been developed to improve the overall quality of laser-drilled holes. The process based on the application of a jet electrolyte, being aligned coaxially with the focused laser beam, on the workpiece surface. The effects of the jet electrolyte during the process mostly consist of electro chemical reaction, effective cooling with materials and transporting debris. A pulsed Nd:YAG laser with frequency doubling is used in the JECM-LD experiments. On the basis of a measurement of laser attenuation in electrolyte, an experimental apparatus system is built and JECM-LD experiments are performed on 0.5mm thickness nickel-based superalloy sheets with the system. The optical microscope is used to detect the experimental results. It is found that the recast layer and spatter have been effectively removed during the JECM-LD compared with laser drilling in ambient atmosphere conditions. The efficiency of JECM-LD with millisecond green laser is about 70% of laser drilling in air.