Experimental study of surface quality during coaxial water-jet assisted nanosecond laser drilling

As a new type of composite processing technology, coaxial water-jet assisted laser drilling (CWALD) has significant advantages in improving the surface quality of micro-holes compared with traditional laser processing. The filling drilling of the DD6 super alloy was carried out by a coaxial water-jet assisted pulsed nanosecond laser. The effects of laser pumping current, laser frequency, and water-jet velocity on the surface quality of micro-holes were studied by response surface methodology (RSM). The results of confocal microscope observation have shown that the surface quality of micro-holes decreases significantly with the increase of laser average power and laser frequency, and increases with the increase of water-jet velocity. This paper expounds on the causes of surface quality defects of micro-holes and uses the optimized process parameters to process micro-holes with low surface line roughness and good roundness.