A packaging machine for producing sealed packages from a web of packaging material having a surface of uneven thickness comprises a pressure roller to press the surface against a corresponding forming roller for sealing the package. The pressure roller comprises an elastically deformable body; and a core of greater rigidity housed therein, with the core comprising a first end surface cooperating with the body, and a radially inner second end surface. The core includes a first portion and a second portion, with the radial distance between the first and second surface at the first portion being greater than at the second portion.