Effects of Laser Etching Al 7075-T6 Alloy in Air and Water
X. Li, X. Xu, H-J. Yu, Y-X. Zhang and X-H. Chen
To achieve high quality machining of Al 7075-T6 alloy, laser etching experiments were carried out in air and water with a fibre laser. The effects of the etching surface morphology, depth and width of Al 7075-T6 alloy are studied. Finite element (FE) software is used to simulate the impact of water on the workpiece surface and the convective heat transfer between laser-water-workpiece. The results show that the impact mainly concentrates on the impact center and decreases on both sides along the impact center. Convective heat transfer mainly concentrates on the laser-water-workpiece contact surface, the convective heat transfer outwards along the jet center presents an annular distribution. When the laser etched Al 7075-T6 alloy in the air, a large amount of slag is accumulated at the bottom of the groove and the ablation phenomenon is obvious. In contrast, when laser etching Al 7075-T6 alloy in water, the depth and width of the groove are smaller than those of laser etching in air, the massive slag and recast layers basically disappear and the surface roughness is smaller. The method of laser etching in water can significantly improve the etching quality of Al 7075-T6 alloy.
Keywords: Fibre laser, Al 7075-T6 alloy, laser etching, air, water jet, groove, convective heat transfer, finite element (FE)