Abstract: An apparatus is disclosed for simultaneously necking and flanging metal cans. A collapsible mandrel is provided, which in the collapsed condition will accept a can and which in the expanded condition grips the can over its entire inside surface. The mandrel is constructed such that in its expanded condition it presents an uninterrupted cylindrical surface. The mandrel has a groove in the region where the necking-flanging operation is to be performed and an elastic material is seated in the groove. A die ring larger in diameter than said mandrel in its expanded condition is mounted rotatably coplanar with said groove and means are provided to move said die ring radially of the mandrel to produce the necking and flanging operation by cooperation with the elastic material in said groove. Expansion and collapse of the mandrel is accomplished by internal cam structure.