This chapter explains the basic terminology and principles of metallurgy as they apply to extrusion. It begins with an overview of crystal structure in metals and alloys, including crystal defects and orientation. This is followed by sections discussing the development of the continuous cast microstructure of aluminum and copper alloys. The discussion provides information on billet and grain segregation and defects in continuous casting. The chapter then discusses the processes involved in the deformation of pure metals and alloys at room temperature. Next, it describes the characteristics of pure metals and alloys at higher temperatures. The processes involved in extrusion are then covered. The chapter provides details on how the toughness and fracture characteristics of metals and alloys affect the extrusion process. The weld seams in hollow profiles, the production of composite profiles, and the processing of composite materials, as well as the extrusion of metal powders, are discussed. The chapter ends with a discussion on the factors that define the extrudability of metallic materials and how these attributes are characterized.

The machinery and equipment required for rod and tube extrusion is determined by the specific extrusion process. This chapter provides a detailed description of the design requirements and principles of machinery and equipment for direct and indirect hot extrusion. It then covers the presses and auxiliary equipment for tube extrusion, induction furnaces for billet processing, handling systems for copper and aluminum alloy products, extrusion cooling systems, and age-hardening ovens. Next, the chapter describes the principles and applications of equipment for the production of aluminum and copper billets. Then, it focuses on process control in both direct and indirect hot extrusion of aluminum alloys without lubrication. The chapter describes the technology of electrical and electronic controls in the extrusion process. It ends with a discussion on the factors that influence the productivity and quality of the products in the extrusion process and methods for process optimization.

Separation of billets by shearing avoids material loss and is considerably faster than sawing or cutting. This chapter discusses the billet shearing process, the characteristics of sheared surfaces, and the effect of various operating parameters on surface quality. It also includes formulas for calculating shearing force, work, and power and describes various ways to increase production rates.

This chapter describes various aspects of the billet making process and how they affect the quality of aluminum extrusions. It begins with an overview of the direct-chill continuous casting technique and its advantages over other methods, particularly for hard aluminum alloys. It then discusses the influence of casting variables, including pouring temperature and cooling rate, and operating considerations such as the make-up of charge materials, fluxing and degassing procedures, and grain refining. The chapter also provides information on vertical and horizontal casting systems, billet homogenization, and the cause of casting defects, including cracking and splitting, segregation, porosity, and grain growth.

This chapter discusses the extrusion characteristics of hard aluminum alloys, particularly those in the 5000 and 7000 series. It begins with a review of two studies, one showing how the extrudability of 7 xxx alloys varies with the presence and amount of different alloying elements, the other relating minimum wall thickness with circumscribing circle diameter. It then explains how oxides on either the billet or container complicate the control of extrusion as well as auxiliary processes and how material flow and the movement of trapped gasses in different regions of the extrusion can lead to defects and variations in strength. It also discusses the extrusion of aluminum matrix composites and explains how composite billets are made.