Ironing is a sheet metal forming process that uniformly thins the workpiece in a specific area. This is a very useful process when employed in combination with deep drawing to produce a uniform wall thickness part with greater height-to-diameter ratio. One example of ironing can be found in the manufacture of aluminum beverage cans, which are actually pressed from flat sheets of thicker material.
Ironing of sheet metal is a manufacturing process that is mostly used to achieve a uniform wall thickness in deep drawings. Variation in wall thickness often exists in parts produced by deep drawing, as discussed in the previous section. Ironing of sheet metal can be incorporated into a deep drawing process or can be performed separately. A punch and die pushes the part through a clearance that will act to reduce the entire wall thickness to a certain value. While reducing the entire wall thickness, ironing will cause the part to lengthen. The percentage reduction in thickness for an ironing operation is usually 40% to 60%.