Packaging steels are nowadays widely used in the beverage and food industry. These steel sheets are covered with a coating for preserving the quality of the content, preventing corrosion and enabling printability at the outside. Such coatings need to comply with strict health and environmental regulations. For this reason, thermoplastic polymers are nowadays used, which are laminated and bonded on the packaging steel. This industrial lamination process needs to handle large volumes at large speeds, and this is where a critical problem emerges. At high line speeds, air bubbles get entrapped between the polymer coating and the steel substrate, which severely affect the quality of the final product. The physics governing this air entrapment process is poorly understood, and the relation with overall process parameters is critical in controlling this. This project will address this problem, using a two-scale modelling strategy, complemented by some experiments. The coarse scale is modelled to establish the link between processing parameters (line speed, roll pressure, temperature, …) and the actual loading conditions in the lamination nip where the film is bonded. The fine scale model descends to the level of the roughness asperities of the steel sheet, where the plastic flow of the film at high temperature into the roughness valleys is explicitly studied.