A method for forming a seam, the method comprising the steps of: rotating a forming cylinder (22) about a rotation axis, the forming cylinder (22) comprising fluid holes (30) and pressure application elements (24) extending radially outward from the forming cylinder (22)； rotate a contact cylinder (42) adjacent to the forming cylinder (22)； advance a first part (11) of substrate in one direction (DM) of the machine over the forming cylinder (22) with a distance (Y) of separation between the fluid hole (30) and the first part (11) of substratum； advancing a second part (12) of substrate in the direction (DM) of the machine, where the first part (11) of substrate is between the second part (12) of substrate and the forming cylinder (22)； heating a fluid at a temperature sufficient to melt, at least partially, the first and second part (11, 12) of substrate； directing a jet of the hot fluid through the fluid hole (30) and over an overlapping area (15) of the first and second part (11, 12) of substrate； partially melt the overlap zone (15)； and compressing the overlap zone (15) into a contact line (40) between the pressure application element (24) and the contact cylinder (42), the method being characterized in that the application application elements (24) Pressure includes fluid outlets (28), each fluid outlet including a fluid hole (30) and the fluid outlet (28) being in fluid communication with a fluid chamber that provides a source of pressurized fluid to supply the fluid hot pressurized at the fluid outlet (28), and the method being further characterized in that the separation distance (Y) between the first part (11) of the substrate and the fluid orifice (30) is maintained with the element (24 ) pressure application.Un método para formar una costura, comprendiendo el método las etapas de: girar un cilindro conformador (22) alrededor de un eje de rotación, comprendiendo el cilindro conformador (22) orificios (30) de fluido y elementos (24) de aplicación de presión
