TABLE OF CONTENTS Extrusion is a process in which a heated billet or ingot of metal is inserted in a chamber called a container and, by means of a hydraulically powered ram, is forced through a die hole of the desired shape. The material movement is in the same direction as the ram stroke. The metal emerges from the die in solidified form and closely conforms in cross section to the shape and dimensions of the die opening. Figure 3.1.1 illustrates the process schematically.
The ram stroke is usually horizontal. A lubricant is often employed to facilitate passage of the metal through the die. In the case of ferrous metals, a common method is the Sejournet process, in which molten glass is applied to the billet as a coating. The glass acts as both an insulator and a lubricant for the steel, which has been heated to the plastic or recrystallization temperature range. After extrusion, the section is...
