The experimental work aims at investigating the influence of surface roughness on heat transfer by using different nozzles. Part of the rough surfaces are provided directly by the industry. These surfaces of casting products possess considerable roughness up to millimeters which can be either unstructured or with typical grooves in the casting direction. The understanding of its effect on cooling hot metals can help to shed light on the quenching process encountered in the industrial applications. This study will initially be carried out with individual nozzles, such as full cone and full jet nozzles, in order to identify the basic relations. Subsequently, a mold is also applied which can be regarded as a series of full jet nozzles. As for the experiments with mold, the plate is moving downwards with a preset velocity; meanwhile, the plate is fixed for experiments with full jet and full cone nozzle.