Removal of paint layer by layer using a 20 kHz 140 ns quasi-continuous wave laser

In this paper, an investigation of laser cleaning of the paint on aluminum substrates using a 20 kHz 140 ns quasi-continuous wave laser was presented both theoretically and experimentally. The temperature distribution and its relationship with the average overlapping rate of adjacent laser spots, which affects the cleaning efficiency, were analyzed and simulated in a two-dimensional calculation model, and the temperature elevation and ablation depth of the paint under the action of quasi-continuous wave laser pulses were obtained. The removal of paint layer by layer is conducted experimentally and compared with the calculation. The quantitative removal of 3 layers of paint with a surface paint of 80 μm, an intermediate paint of 50 μm, and a primer paint of 50 μm was realized. The laser removal of paint involves the heating of the paint to a critical temperature by absorbing certain number of laser pulses and the vaporization of the heated paint. The experimental results show that the experimental results agree well with the simulated results when the paint is relatively thick. In the case that the thickness of paint becomes thinner, the simulation results does not agree well with the experimental results, a more comprehensive model considering heat conduction effect of the substrate is needed.