Abstract: When 1 064 nm laser was used to clean 2024 aluminum alloy skin surface fluorocarbon paint layer, the change of surface roughness caused the alteration of absorption effect of paint layer on laser, which easily causes excessive absorption of heat to produce substrate damage. Therefore, for the detection and analysis of surface roughness in the laser cleaning process, the pulsed laser cleaning experimental system was designed. The generation mechanism of surface roughness morphology of fluorocarbon paint layer was analyzed under two laser cleaning modes, and the surface roughness was tested and characterized by laser scanning confocal microscope. The evolution of surface roughness was studied when the fluorocarbon paint layer was removed by laser. The result showed that: 1) The laser ablation mechanism and vibration mechanism will produce rough surface in the laser cleaning process; 2) With the increase in the times of laser cleaning, the surface roughness presents the nonlinear increase in the laser layer-by-layer cleaning process. After the laser cleaning 14 times, the roughness of the paint layer has reached 35.88μm, which is an increase of 370% compared to that of the first cleaning. 3) The presence of rough surface has a significant increase effect on the laser absorption rate in the process of laser layer by layer paint removal. After the laser cleaning 7 times, the absorption rate of the rough surface of the paint layer on laser increase by 32.8%.

Key words: laser cleaning, fluorocarbon paint, rough surface, detection and analysis