This paper deals with the occurrence of plastic creases, called wrinkles, in a strip travelling through a continuous processing line. During this process, strips run over numerous rolls under global tension. Finite element analyses are carried out to model the formation of wrinkles when a strip is passing over a roll. When the strip is stretched, transverse compressive stresses appear near the roll and cause the strip buckling. Simulations have shown that friction between sheet and roll induces an increase of the amplitude of the buckles. In some cases, a plastic cumulative mechanism is triggered and leads to the occurrence of a wrinkle. A description of these phenomena is proposed.