Stainless steel manufacturing has experienced a high growth. Nowadays the stainless steel manufacturing is an industry with many applications. Annealing process is an important process in the production of stainless steel coils. The aim of this research is to obtain the classification of defective annealed coils. So a nonlinear mathematical model has been developed for the annealing process. In this research the following techniques have been used: SOM neural networks and classifications methods. For testing, temperature signals were collected along the annealing furnace, also speed signal of the production line were collected. These signals are correlated with each one of the manufactured coils.