Development of a new coating technology with the help of a slot die

This project aimed at the development of a method for thin coatings of varnish on metal sheets. For the deposition of the fluid on the substrate a slot die was used. The experimental measurements have been carried out together with an industrial partner in a production scale. In addition to the measurements the slot die has also been modelled in 2D and 3D, thus allowing for numerical investigation of the coating behaviour in OpenFOAM®. The investigations led to a set of parameters which were varied in order to reach the thinnest possible coating. The parameters included volume flow, slot die height and lip distance, different viscosities and velocity of the moving substrate. They had to be varied not just under the aspect of coating thickness, but also in respect to coating stability, meaning that the coating had to stay continuous and without the enclosure of air bubbles.

Instable coating on the metal surface in a two-dimensional simulation.