A machine for corrugating preformed plates that form the core element of a heat exchanger. A fold forming mechanism imparts an initial fold in the deformable links joining a series of preformed plates received from an external source. A gathering mechanism gathers the folded series of preformed plates to produce a flow of pairs of mating plates. Precut lengths of corrugated fins are then inserted between joined adjacent pairs of mating plates and a cut-off mechanism severs the deformable links of preselected pairs of links joining pairs of mating plates to separate individual core elements from the flow of plates.