This chapter provides an overview of the basic principles and historic development of metal extrusion processes. It starts by illustrating the two major process categories: direct extrusion and indirect extrusion. It then briefly defines hydrostatic extrusion and the conform process. The history coverage addresses early patents for extrusion of lead at the turn of the 17th century up through the major process innovations in the 20th century.

This chapter discusses the extrusion characteristics of relatively soft aluminum alloys. It begins by identifying alloy designations within the class and the types of extrusions made from them. It then explains how extruded shapes and cross-sections are defined and how to analyze and assess important process variables such as runout, extrusion pressure, ram speed, and butt thickness. It also provides best practices for various operations and explains how to identify and remedy common extrusion defects.