An ultrasonic sealing system in a machine for making composite webs in the production of absorbent sanitary articles includes a contact roller having an axis of rotation and including a central portion and a peripheral portion which is supported by the central portion and includes an outer surface forming the outer surface of the contact roller itself. The contact roller includes a sealing pattern on the outer surface of the peripheral portion and also includes springs acting between the central portion and the peripheral portion, which is supported by the peripheral portion by means of the springs.
