The laser processing technology of metal material is developing with a trend of low surface roughness, small heat-affected zone and high depth-diameter ratio. Recently, a kind of water-conducting laser processing technology has been developed based on water-jet coupling technology. In this technology, the laser is completely reflected at the interface between water jet and air. The flushing and cooling effect of water jet improve the surface roughness and decrease the size of heat-affected zone. The water jet in steady state which can be used to conduct laser and remove material has high depth-diameter ratio. And this technology also makes laser processing of structures with high depth-diameter ratio become possible.

  To reveal the material removing feature of water-conducting laser processing technology, a set of water-conducing laser processing equipment is developed. This equipment consists of coupling and observation system, motion control system and water supply system. The experiments of water-conducting laser processing for C276 alloy and SAE 1070 alloy are carried out. The laser used in experiments has a wavelength of 532 nm. The diameter of water jet nozzle hole is 100 μm and the diameter of water jet is about 83 μm. Holes and groves are machined on both materials and the morphology of machining zone is measured by Leica DVM6 digital microscope.

  In the blind hole machining experiment, the edge of hole is regular and smooth. And the diameter of blind hole is larger than the diameter of water jet. The reason is that the side walls of blind hole also absorb the energy of laser in machining process. And the diameter of blind holes machined for longer time is also bigger. But there is molten sediment around the blind hole for the reason that the drainage condition in blind hole machining is not good. The water connot flush the molten materials away efficiently. To improve the drainage condition of water and eliminate the molten sediment, the rotary cutting method can be used.

  In the grove machining experiment, the edges of grooves are straight and without burrs, and there is no heat-affected zone in both materials. The section shape of grove is nearly a fillet triangle, and the reason is that the central part of water jet has higher energy density. In the machining of grove, no molten sediment is observed because the flow of water is unimpeded and the water brings molten sediment away efficiently.

  The material removing feature of water-conducting laser processing technology is revealed and the results of machining experiments show that water-conducting laser processing technology on metal precision machining is practical and has important application value.