Submerged entry nozzle connects the tundish and the mold in the continuous casting of steel. Continuous casting is usually done in series including 3–6 successive heats. Casting of a heat takes about 35-50 minutes. The nozzle is changed after each series and the new series is started with a new nozzle. About 360-720 tons of steel goes through a nozzle during its lifetime.

The casting speed and the stopper rod position give the indication of nozzle clogging, but they cannot, however, answer the question, how long time the casting can continue and when the nozzle should be changed. In this paper, feedforward neural networks with backpropagation training were used in modelling the nozzle clogging behaviour at Rautaruukki Steel mill, at Raahe site.