This article addresses dies and die materials used for hot forging in vertical presses, hammers, and horizontal forging machines (upsetters). It reviews the properties of die materials for hot forging, including good hardenability, resistance to wear, plastic deformation, thermal fatigue, and mechanical fatigue. The article describes heat treating practices commonly employed for chromium- and tungsten-base AISI hot-work tool steels. It discusses the fabrication of impression dies, and the advantages and disadvantages of cast dies. The article concludes with a discussion on the factors that affect die life and safety precautions to be considered during die construction.

Forging machines use a wide variety of hammers, presses, and dies to produce products with the desired shape, size, and geometry. This article discusses the major types of hammers (gravity-drop, power-drop, high speed, and open-die forging), and presses (mechanical, hydraulic, screw-type, and multiple-ram). It further discusses the technologies used in the design of dies, terminology, and materials selection for dies for the most common hot-forging processes, particularly those using vertical presses, hammers, and horizontal forging machines. A brief section is included on computer-aided design in the forging industry. Additionally, the article reviews specific characteristics, process limitations, advantages, and disadvantages of the most common forging processes, namely hot upset forging, roll forging, radial forging, rotary forging, isothermal and hot-die forging, precision forging, and cold forging.

Thread rolling is a cold-forming process for producing threads or other helical or annular forms by rolling the impression of hardened steel dies into the surface of a cylindrical or conical blank. Methods that use cylindrical dies are classified as radial infeed, tangential feed, through feed, planetary, and internal. This article focuses on the capabilities, limitations, and machines used for these methods. It describes the three characteristics, such as rollability, flaking, and seaming, used in evaluating and selecting metals for thread rolling. The article explores the factors affecting die life and explains the effect of thread form on processing. It provides information on various fluids used in thread rolling to cool the dies and the work and to improve the finish on the rolled products. The article provides a comparison between thread rolling and cutting, as well as between thread rolling and grinding.

This article describes die wear and failure mechanisms, including thermal fatigue, abrasive wear, and plastic deformation. It summarizes the important attributes required for dies and the properties of the various die materials that make them suitable for particular applications. Recommendations on the selection of the materials for hot forging, hot extrusion, cold heading, and cold extrusion are presented. The article discusses the methods of characterizing abrasive wear and factors affecting abrasive wear. It discusses various die coatings and surface treatments used to extend the lives of dies: alloying surface treatments, micropeening, and electroplating.

This article discusses the mechanics, surface preparation and principles of metal forming operations such as drawing, bending (draw bending, compression bending, roll bending, and stretch bending), spinning, and straightening of bars, tubes, wires, rods and structural shapes. The article also discusses the machines and tools, including dies and mandrels, and lubricants used for these metal forming operations.

Cold heading is typically a high-speed process where a blank is progressively moved through a multi-station machine. This article discusses various cold heading process parameters, such as upset length ratio, upset diameter ratio, upset strain, and process sequence design. It describes the various components of a cold-heading machine and the tools used in the cold heading process. These include headers, transfer headers, bolt makers, nut formers, and parts formers. The article explains the operations required for preparing stock for cold heading, including heat treating, drawing to size, machining, descaling, cutting to length, and lubricating. It lists the advantages of the cold heading over machining. Materials selection criteria for dies and punches in cold heading are also described. The article provides examples that demonstrate tolerance capabilities and show dimensional variations obtained in production runs of specific cold-headed products. It concludes with a discussion on the applications of warm heading.

This article provides a summary of the overall development of the finite element method (FEM) and its contribution to the materials forming industry. It presents an overview of FEM methodologies and applications in the order of their usage in typical manufacturing (bulk forming process) process sequence: primary materials processing, hot forging and cold forming, and product assembly. The article discusses the material fracture and dies stress analysis and presents the optimization techniques used in 2-D and 3-D preform die design.

Coining is a closed-die forging operation in which all surfaces of the workpiece are confined or restrained, resulting in a well-defined imprint of the die on the workpiece. This article focuses on the coining equipment (hammers and presses), lubricants, and general and special die materials used in the coining process. It discusses the coinability of metals such as steels, copper, and composite metals. The article describes the control of dimensions, surface finishes, and weight of coined items. It concludes with a discussion on processing problems and solutions.

This article describes the presses that are mechanically or hydraulically powered and used for producing sheet, strip, and plate from sheet metal. It also presents the JIC standards for presses, compares the presses based on power source, details the selection criteria and provides information on the various drive systems and the auxiliary equipment. It describes the selection of die materials and lubricants for sheet metal forming and provides information on the lubrication mechanisms and selection with a list of lubricant types for forming of specific sheet materials of ferrous or nonferrous metals. The article reviews the various types of forming processes such as blanking, piercing, fine-edge blanking, press bending, press forming, forming by multiple-slide machines, deep drawing, stretch forming, spinning, rubber-pad forming, three-roll forming, contour roll forming, drop hammer forming, explosive forming, electromagnetic forming, and superplastic forming.

This article presents a detailed account of the welding parameters, equipment needed, applications, advantages, limitations, and the process variables affecting various types of resistance welding operations, namely, resistance spot welding, resistance seam welding, resistance projection welding, and flash welding.

This article focuses on forging processes and equipment, types of forging alloys, and the forging practices associated with the forging of copper and copper alloys. An overview of the forging tolerances for small copper-base forgings is presented in a table.

Cemented carbides belong to a class of hard, wear-resistant, refractory materials in which the hard carbide particles are bound together, or cemented, by a ductile metal binder. Cermet refers to a composite of a ceramic material with a metallic binder. This article discusses the manufacture, composition, classifications, and physical and mechanical properties of cemented carbides. It describes the application of hard coatings to cemented carbides by physical or chemical vapor deposition (PVD or CVD). Tungsten carbide-cobalt alloys, submicron tungsten carbide-cobalt alloys, and alloys containing tungsten carbide, titanium carbide, and cobalt are used for machining applications. The article also provides an overview of cermets used in machining applications.

This article discusses the production of low-alloy steel parts by powder forging, focusing on the material considerations, such as hardenability and inclusion assessment; and process considerations, including sintering and reheating, metal flow, and secondary operations. It presents the mechanical property data for copper and graphite powders mixed with an iron powder base to produce materials that generally contain 2″ Cu, including tensile, impact, and fatigue properties. Heat treatment procedures used in developing the properties of the prealloyed powder forged materials are also covered. Finally, the article describes the process steps and cost considerations in metal injection molding (MIM) and tabulates the composition, and mechanical properties of MIM low-alloy steels.

This article describes the different types of precipitation and transformation processes and their effects that can occur during heat treatment of various nonferrous alloys. The nonferrous alloys are aluminum alloys, copper alloys, magnesium alloys, nickel alloys, titanium alloys, cobalt alloys, zinc alloys, and heat treatable silver alloys, gold alloys, lead alloys, and tin alloys. It also provides a detailed discussion on the effects due to precipitation and transformation processes in these non-ferrous alloys.

The compression molding process is most commonly called the sheet molding compound (SMC) process in reference to the precursor sheet molding compound material it uses. This article discusses the types of materials used for sheet manufacture, and describes the manufacturing and processing parameters of SMC components, providing details on tooling and process advantages and limitations. The article provides a general overview of the types of compression molding processes, including structural compression molding and thermoplastic compression molding.

This article describes the extrusion process, which converts soft, plastic material into a particular form using an extruder, or screw conveyer. It discusses the two main types of plastic extruders, twin-screw and single-screw, estimation of extruder capacity, and design and operations (heating, cooling, downstream sizing, corrugating, and crossheading) of the screw, the most important component of any extruder. It discusses the shapes produced by screw extrusion and the types of extrusion products produced by extrusion processes, including blown-film extrusion, flat-film or sheet extrusion, chill-roll film extrusion, pipe or tube extrusion, wire and cable coverings, extrusion coating, and profile extrusion, and provides some discussion on multiple-screw extruders. The article describes the dimensional accuracy of extrusion products, and lists common defects that occur frequently in the extrusion process.

The most widely accepted alloy and temper designation system for aluminum and its alloys is maintained by the Aluminum Association and recognized by the American National Standards Institute (ANSI) as the American National Standard Alloy and Temper Designation Systems for Aluminum (ANSI H35.1). This article provides a detailed discussion on the alloy and temper designation system for aluminum and its alloys. The Aluminum Association alloy designations are grouped as wrought and cast alloys. Lengthy tables provide information on alloying elements in wrought aluminum and aluminum alloys; nominal composition of aluminum alloy castings; typical mechanical properties of wrought and cast aluminum alloys in various temper conditions; and cross references to former and current cast aluminum alloy designations.