Method of manufacturing a heat exchanger

A method of manufacturing a heat exchanger comprising a plurality of fin members each including:

• a flat-plate rectangular base having a predetermined width;
• and
• a plurality of fins having the same shape and protruding from the base, the fins being arranged in parallel and in a row in a longitudinal direction of the base so that slit portions with no fin are formed on both side ends of the base in a width direction of the base,
• the fin members being arranged in a frame through which a refrigerant will flow so that the adjacent bases abut on each other in the width direction,
• wherein the method comprises producing the fin members by:
• an extrusion molding operation of extrusion-molding a long fin member in which a plurality of long fins extends in a direction of extruding the long fin member and protrudes from a flat-plate-shaped long base;
• a fin cutting operation of cutting the long fins of the long fin member, immediately after the extrusion molding operation, by a predetermined width into the fins by a plate-shaped upper die placed perpendicular to the extrusion direction;
• and
• a base cutting operation of cutting the long base of the long fin member in a long-fin cutting region made in the fin cutting operation so that the slit portions are formed.