This article discusses the operation of upset forging machines and selection of the machine size. It describes several types of upsetter heading tools and their materials. The article reviews the cold shearing and hot shearing methods for preparing blanks for hot upset forging. It deals with various upsetting processes: offset upsetting, double-end upsetting, upsetting with sliding dies, upsetting pipe and tubing, and electric upsetting. The article also provides information on hot forging and cold forging.

This article lists functions of lubricants common to the majority of applications and processes. It discusses the lubricant candidates widely used in forging: conversion coatings with soaps (stearate compounds) and molybdenum disulfide for cold forging; oil-based thick, film oil or polymerbased lubricants and molybdenum disulfide for warm application; graphite suspensions in oil or water for hot forging steels; and glass films for titanium and superalloys hot forgings. The article describes the applications of lubricants in warm extrusion and forging, hot forging of steel, hot forging of aluminum, isothermal and hot die forging, and the extrusion of steel.

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 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.

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.

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.

Radial forging is a hot- or cold-forming process that uses two or more radially moving anvils or dies to produce solid or tubular components with constant or varying cross sections along their lengths. This article focuses on the workpiece configuration, workpiece materials, machines, dies, advantages, and limitations of radial forging. It concludes with a discussion on the applications of radial forging.

Workability in forging depends on a variety of material, process-variable, and die-design features. A number of test techniques have been developed for gaging forgeability depending on alloy type, microstructure, die geometry, and process variables. This article summarizes some common workability tests and illustrates their application in practical forging situations. Workability tests for open-die forging of cast structures, hot and cold open-die forging of recrystallized structures, fracture-controlled defect formation, establishing effects of process variables and secondary tensile stresses on forgeability, and flow-localization-controlled failure are some common tests. The workability test used for closed-die forging is also summarized.

Precision forging is defined as a closed-die forging process in which the accuracy of the shape, dimensional tolerances, and surface finish exceed normal expectations to the extent that some of the postforge operations can be eliminated. This article provides an overview of the key factors that impact the precision forging process. It provides information on the achievable tolerances and presents examples of precision forging. A discussion on forging of bevel gears/spiral bevel gears is also presented.

This article begins with discussion on forgeability and the factors affecting the forgeability of aluminum and aluminum alloys. It describes the types of forging methods and equipment and reviews critical elements in the overall aluminum forging process: die materials, die design, and die manufacture. The article discusses the critical aspects of various manufacturing elements of aluminum alloy forging, including the preparation of the forging stock, preheating stock, die heating, lubrication, trimming, forming and repair, cleaning, heat treatment, and inspection. It concludes with a discussion on the forging of advanced aluminum materials and aluminum alloy precision forgings.

Radial forging is a process performed with four dies arranged in one plane that can act on a piece simultaneously. This article explains the types of radial forgings and describes the advantages and disadvantages of radial forging over open-die cogging/forging. The article discusses the parameters involved in product shape control. It also provides examples that illustrate the versatility and capabilities of the radial forge machine.

This article focuses on the forging characteristics of different types of refractory metals and alloys, namely, niobium and niobium alloys, molybdenum and molybdenum alloys, tantalum and tantalum alloys, and tungsten and tungsten alloys.

This article focuses on the forging behavior and practices of carbon and alloy steels. It presents general guidelines for forging in terms of practices, steel selection, forgeability and mechanical properties, heat treatments of steel forgings, die design features, and machining. The article discusses the effect of forging on final component properties and presents special considerations for the design of hot upset forgings.

This article provides an overview of the capabilities of closed-die forging. One of the most important aspects of closed-die forging is proper design of preforming operations and of blocker dies to achieve adequate metal distribution. The article describes the effects of friction and lubrication in forging. It discusses the types of closed-die forgings, namely, blocker-type, conventional, and close-tolerance. The article illustrates the classification of forging shapes and explains how to predict the forging pressure and the control of die temperature during closed-die forging. It explains the use of heating equipment for closed-die forging and tabulates the maximum safe forging temperatures for carbon and alloy steels. The article concludes with a discussion on a trimming method used for closed-die forgings.

Hammers and high-energy-rate forging machines are classified as energy-restricted machines as they deform the workpiece by the kinetic energy of the hammer ram. This article provides information on gravity-drop hammers, power-drop hammers, die forger hammers, counterblow hammers, and computer-controlled hammers. It describes the three basic designs of high-energy-rate forging (HERF) machines: the ram and inner frame, two-ram, and controlled energy flow. The article reviews forging mechanical presses, hydraulic presses, drive presses, screw presses, and multiple-ram presses.

Powder forging is an extension of the conventional press and sinter powder metallurgy process, which is recognized as an effective technology for producing a variety of parts to net or near-net shape. This article focuses on the material considerations, such as powder characteristics, alloy development, and inclusion assessment; and process considerations, such as process stages, tool design, and secondary operations; of ferrous alloy powder forging. The mechanical properties of powder forged materials are also reviewed. The article discusses the quality assurance tests for powder forged materials: the part dimensions and surface finish measurement, magnetic particle inspection, metallographic analysis, and nondestructive testing. It concludes with a discussion on the applications of powder forged parts with examples.

This article discusses the forging processes and equipment and forging practice associated with the forging of magnesium alloys. It describes the workability of magnesium alloys. The article concludes with a discussion on the inspection of magnesium alloy forgings.

Stainless steels, based on forging pressure and load requirements, are more difficult to forge because of the greater strength at elevated temperatures and the limitations on the maximum temperatures at which stainless steels can be forged without incurring microstructural damage. This article discusses the forging methods, primary mill practices (primary forging and ingot breakdown), trimming, and cleaning operations of stainless steels. It describes the use of forging equipment, dies, and die material in the forging operation. The article provides an overview of the forgeability of austenitic stainless steels, martensitic stainless steels, precipitation-hardening stainless steels, and ferritic stainless steels. It concludes with a discussion on the heating and lubrication of dies.

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.

Forging of nickel-base alloys results in geometries that reduce the amount of machining to obtain final component shapes and involves deformation processing to refine the grain structure of components or mill products. This article discusses the heating practice, die materials, and lubricants used in nickel-base alloys forging. It describes two major forging processing categories for nickel-base alloys: primary working and secondary working categories. Primary working involves the deformation processing and conversion of cast ingot or similar bulk material into a controlled microstructure mill product, such as billets or bars, and secondary working refers to further forging of mill product into final component configurations.