Search Results for extrusion

This chapter introduces basic extrusion concepts, including types, processes, mechanics, and the principal variables and their effects on extrusion. The chapter defines the two basic types of extrusion commonly used in the aluminum extrusion industry, direct and indirect. The chapter discusses the mechanics of extrusion including plastic deformation and metal flow, plastic strain and strain rate, extrusion pressure, and extrusion force. The principal variables of extrusion, including billet material flow stress, extrusion ratio, dead-metal zone semiangle, speed of deformation, and extrusion temperature are discussed.

Tribology plays a critical role in extrusion. This chapter provides an overview of tribology in extrusions including a discussion about the friction models at various locations of the extrusion tooling/die material interfaces and a discussion about wear and lubrication in extrusion die and tooling. The chapter shows a flow diagram highlighting the significant input variables necessary for computer simulation using the fundamentals of friction and thermodynamics models. The chapter explains the influence of principal variables on temperature rise in extrusion. It describes the most common industrial methods of isothermal extrusion of aluminum alloys.

This chapter discusses the extrusion technology of soft- and medium-strength aluminum alloys. The relative extrudability ratings of some soft- and medium-grade alloys are given. The chapter presents useful extrusion parameters and their relationships associated with day-to-day production practices in the aluminum extrusion industry. Useful parameters discussed include: extrusion runout; extrusion pressure; ram or extrusion speed control; and butt or extrusion discard thickness control. The chapter provides fundamental approaches to introducing and developing the design of experiments (DOE) for the aluminum extrusion plant to improve overall productivity. It also focuses on heat treatment of aluminum alloys.

This chapter discusses the extrusion technology of hard alloys. The chapter provides an overview of hollow extrusion for aerospace application. It presents extrusion defects related to hard alloys. The chapter describes the extrusion quality requirements for aerospace applications. It also discusses extrusion of aluminum-matrix composites. The chapter outlines the powder metallurgy process for making billets for extrusion.

Variables affecting the cost of aerospace extrusions, including extrusion geometry, billet alloy, press size, order quantity, and the length of extrusion and final temper, are discussed in this chapter. Energy and labor inputs at various stages for aerospace extrusions are shown. The chapter offers insights into the economics of producing aerospace extrusions in a highly competitive global business market.

In this chapter, process control of each operational stage is discussed, with a detailed process-control flow diagram to provide a better understanding and to create a process-control document of each operational process stage. This chapter also presents fundamental ideas of a complete process- and quality-control framework system of an aluminum extrusion plant, starting from alloy and billet making to the final heat treatment process parameters required to bring the extrusion to the final alloy and temper designation to meet product requirements.

This chapter deals with the mechanics and tribology associated with the extrusion of bars, sections, and tubes. It covers direct and indirect extrusion processes in detail and demonstrates the use of important equations, relationships, and measurements for determining pressure, force, material flow, friction, die wear, heat generation, and lubrication requirements. The chapter also provides information on hydrostatic, friction-assisted, and severe plastic deformation extrusion processes, discusses the cause of instabilities and defects, and explains how to select and apply lubricants to minimize friction and die wear when extruding steel, aluminum, copper, and refractory metals.

Aluminum shapes, rod, bar, tubes, and wire may be produced directly as extrusions or by subsequent processing of continuous cast stock. This chapter describes the key aspects of aluminum extrusion and wire production focusing on the more common hot extrusion process and presenting the general types of aluminum extrusion alloys. An overview of free-machining alloys and products, and weldable 6xxx and 7xxx high-strength structural alloys is also provided.

This chapter opens with a discussion of the classification of rod and tube extrusion processes. The standard processes involve hot working (extrusion at temperatures above room temperature), but some specialized cold working processes are also used for rod and tube extrusion. The next section reviews principles, variations, thermal conditions, axial load calculation, material flow, and applications of direct extrusion and indirect extrusion, with examples provided for extrusion of aluminum and copper alloys. Next, the chapter focuses on the process principles, advantages, and applications of conventional hydrostatic extrusion and thick film processes. This is followed by sections providing information on the special extrusion processes, namely conform process and cable sheathing. The chapter ends with a discussion on direct and indirect tube extrusion.

The aim of every extrusion plant is the efficient production of competitive products that meet the appropriate quality requirements. This chapter discusses the processes involved in the selection and introduction of a quality management system, along with its application, advantages, and disadvantages. It describes the process chain for order processing within the quality circle and provides information on product liability legal issues. In addition, the chapter discusses the processes involved in quality control, along with its organization, responsibilities, audits, and testing.

This chapter discusses the basic differences between direct and indirect extrusion, the application of plastic theory, the significance of strain and strain rate, friction, and pressure, and factors such as alloy flow stress and extrusion ratio, which influence the quality of material exiting the die and the amount of force required.

This chapter provides an overview of the thermodynamics of extrusion. It begins by presenting a thermodynamic model of the extrusion process expressed in the form of finite difference equations. It then explains how the model accounts for multiple sources of heat generation, the influence of principal variables on temperature rise, and different types of temperature measurements. It also discusses the benefits of isothermal extrusion and how it achieves consistent mechanical properties in extruded components.

This chapter covers the different types of extrusion presses in use, discussing their relative advantages, operating parameters, and selection factors. It describes the function of major components, including containers, stems, dummy pads, and die carriers, the maintenance they require, and their impact on productivity and the quality of extrusions. It also discusses the integration of auxiliary equipment such as log heaters and shears, quench systems, die ovens, pullers, stretchers, and stackers.

This chapter familiarizes readers with the design, configuration, and function of tooling and dies used to extrude aluminum alloys. It discuses basic design considerations, including the geometry, location, and orientation of die openings; allowances for thermal shrinkage, stretching, and deflection; and the length and profile of bearing surfaces. It outlines the steps and processes involved in die making, describes the selection and treatment of die materials, and examines the factors that influence friction and wear. It also discusses the general procedures for on-site die correction.

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.

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.

This chapter provides guidelines on how to set up and run an effective quality-improvement program for aluminum extrusion operations. It begins by identifying production processes and variables that impact the quality of hard and soft alloy extrusions. It then presents a series of checklists and flowcharts that can be used to monitor and troubleshoot billet-making and extrusion processes, die construction, equipment maintenance, heat treating, and sawing and stretching procedures. It also discusses the importance of charting test results and monitoring surface treatments that may be required to improve corrosion, oxidation, or wear resistance.

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.