Abstract: A procedure for obtaining partially corrugated sheet metal (11) comprises the following work phases: provision of a roll of sheet metal (11) to feed a respective means of unrolling and transferring said sheet metal (11); compression of said sheet (11) in such a way as to produce a series of transverse corrugations alternating with flat sections on the sheet (11); transfer of said sheet (11) towards a press brake (16) to fold the sheet, parallel to the axis of the corrugations, in correspondence of the central portion of each flat section, and in the opposite direction with respect to the fold of the previous flat section in such a way as to obtain a coil of sheet metal (11) with corrugations on adjacent sides; extraction of the corrugated sheet (11) from the press brake (16) and shearing of said sheet (11) into pre-established lengths. Through such procedure it is possible to manufacture an improved air-air plate-type heat exchanger.