Automotive paint spray characterization and visualization

Understanding the automotive paint atomization and how the atomized paint droplets are transferred from the atomizer to the target surface is a necessary step in the continuous improvement of the paint application process. Ensuring increased transfer efficiency and improvement in coated surface quality require continuous improvement in the application process and reformulation of the paint, especially for metallic paints to satisfy consumer demands. The solutions for these problems require multiple approaches-such as new paint formulation, operation optimization, new paint applicator designs, and improved understanding of the paint droplet transfer process. The ability to visualize the internal structures of the paint spray transfer process is vital to understanding the role that the atomization mechanisms have on the evolution of the paint droplets as they travel from the paint applicator to the target surface. This chapter, therefore, seeks to address some of these issues by focusing on the visualization and characterization of the paint spray transfer process. This chapter discusses existing and new technologies for paint spray visualization and characterization, with particular emphasis on a new technique that uses infrared thermography based approach. This technique allows the visualization of the internal structures and the macroscopic features of the paint spray transfer process. In addition, the paint droplet volume fraction and the paint droplet number density inside the spray are computed by the new technique. This provides quantitative information about the droplet distribution inside the continuous gas phase.