Optimisation of a paint coating ablation process by CO2 TEA laser: Thermal field modelling and real-time monitoring of the process

The ablation of coatings (paint, varnish, oxides, etc.) using a pulsed laser beam is a process that has a number of major benefits compared with conventional cleaning techniques (mechanical and chemical), the main advantage being the possibility of removing the surface layer without any risk of damaging the substrate. Another benefit, and certainly not the least, is the non-use of toxic solvents or chemical products that are difficult to eliminate and, in any case, will be banned from use in the near future. However, it must be stressed that, notwithstanding the above benefits, laser ablation of painted surfaces can only give good quality results if the process is properly controlled. The procedure discussed in this paper has two aims: the first involves establishing a thermal model of the interaction, applied to the ablation of paint from metal surfaces by infra-red laser. The second involves proposing an optimised paint removal process validated by experimental measurements. This second objective will be based on an analysis method of the acoustic signal transmitted by the ablation plasma beam.