Producing ultra-high aspect ratio micro holes in difficult-to-cut materials remains a challenge. Laser and electrochemical machining (LECM) could fabricate micro holes with high surface quality and efficiency. However, the machining stability and efficiency deteriorated with the increase in depth due to the difficulties in flushing the machining products out of the machining area. Moreover, the precision of the inlet was affected by the stray current corrosion. In this paper, a hybrid tool electrode based LECM was proposed to fabricate deep micro holes, in which the mixed electrolyte containing sodium citrate (C 6 H 5 Na 3 O 7 ) and coaxial electrolyte vacuum suction were adopted to enhance the mass transport in the machining gap. Simulation results showed that electrolyte vacuum suction could improve the electrolyte flushing rate in the machining gap. The C 6 H 5 Na 3 O 7 could inhibit the generation of insoluble electrolytic products, improve the machining precision, and decrease the stray current area by 79.5%. In LECM using mixed electrolyte, laser irradiation could improve both the materials removal rate. However, the precision of the micro holes decreased with the increase in laser coupling power. Moreover, the coaxial electrolyte vacuum suction could improve the consistency of the diameter by 75% and the surface roughness of the deep micro holes along the depth, and enhance the machining stability of LECM. The step-changing feeding rate of the hybrid tool electrode was proposed to enhance the stability of the drilling process. Micro holes with a depth of 200 mm and an aspect ratio of 148:1 were drilled in a nickel-based superalloy.
Dong et al. (Tue,) studied this question.