Simulation of the coating film appearance for spray application

The coating film topography depends on the substrate structure, the application parameters and the coating material's levelling properties. Substrates consisting of several materials with different surface structures and differently inclined areas make a homogenous coating film structure difficult. By means of simulations, the paint film structure is intended to be controlled so that the theoretical optimum is reached and the experimental effort can be reduced. The focus is on spray application in the automobile industry where appearance requirements are particularly high. In the self-developed simulation program, the shot noise model is used to form the initial coating film topography by superimposing ball caps. The droplet size distribution can be measured or specified by a fictitious probability distribution within the program. In the next simulation step, the initial topography partly levels. The levelling model includes the following components of structure change: sine component of the weight force, cosine component of the weight force, surface tension component, surface tension gradient component, sheer force on the surface and evaporation.