Metal containers and methods of manufacture

A method of reducing a thickness and increasing a height of a cylindrical wall of a metal cup so as to form a can body, the method comprising:

• positioning a wall-ironing punch inside the cup, the punch including:
• a first punch portion having a first diameter,
• a second punch portion having a second diameter,
• a third punch portion having a third diameter;
• a first transition between the first punch portion and the second punch portion such that the second punch portion diameter is greater than the first punch portion diameter;
• wherein the first punch portion corresponds to a closed end of the cup;
• and
• a second transition between the second punch portion and the third punch portion such that the third punch portion diameter is greater than the second punch portion diameter;
• moving an annular wall-ironing die axially over the closed end of the cup towards an open end of the cup, such that the wall-ironing die does not move beyond the open end of the cup, in order to iron the cylindrical wall from the closed end up to a position axially spaced from the open end, thereby forming the can body;
• moving the wall-ironing die back in an opposite direction to remove the can body from the die;
• and
• forming a curl at an uppermost end of the can body;
• thereby forming a body-wall of the can body having a wall thickness proximate a base of the can body that is greater than a wall thickness of a second body-wall portion.