Summary
In order to prevent solvent emissions, powder coating is increasingly used in the coating industry as a more up to date and environment-friendly alternative to wet lacquering. The growth in potential applications for this technology, in the automobile industry among other sectors, has led to a sharp increase in the stringency of requirements for the visual quality and reproducibility of powder coatings in recent years.
Given this context, this project involved the development of experimental and numerical methods to predict the dispersion of powder particles between the spraying device and the object to be coated.
To this end, a numerical flow calculation program has been extended to allow the additional consideration of electric field strengths affecting the movement of particles and the space charge. Calculated values have been compared with data derived from experiments using optical measuring devices.
Results:
Using the calculation program, it has been possible to determine the resulting coating thickness distribution and coating efficiency for the coating of flat sheet metal with sufficient accuracy, on the basis of flow conditions in the powder spray gun. This has a number of associated advantages:
- Process simulation without the need for expensive experimental investigations
- Improved cost-effectiveness associated with minimal coating powder consumption
- Improved operational reliability of the overall coating process
- Scope for parametric analyses for the further improvement of spray gun and nozzle technology.
