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 discusses the three characteristics that are important in evaluating and selecting metals for thread rolling, namely, rollability, flaking, and seaming. It reviews the capabilities and limitations of flat-die rolling, radial-infeed rolling, tangential rolling, through-feed rolling, planetary thread rolling, continuous rolling, and internal thread rolling, as well as the rolling machines and dies used. The article describes the factors affecting die life and provides information on radial die load, seam formation, surface finish, and thread dimensions that are affected by the form of the thread. It explains the reasons for using fluids in thread rolling. The article concludes with a comparison of rolling with cutting and grinding.

Metalworking is one of the three major technologies used to fabricate metal products. This article tabulates the classification of metal forming processes. It discusses different types of metalworking equipment, including rolling mills, ring-rolling machines, and thread-rolling and surface-rolling machines. The article outlines the significant characteristics of pressing-type machines: load and energy characteristics, time-related characteristics, and accuracy characteristics. It summarizes different specialized processes such as advanced roll-forming methods, equal-channel angular extrusion, incremental forging, and microforming. The article describes the thermomechanical processing of nickel- and titanium-base alloys and concludes with information on the advancements in process simulation.

This article focuses on various heat treatment practices recommended for different types of high-speed tool steels. Commonly used methods include annealing, stress relieving, preheating, austenitizing, quenching, tempering, carburizing, and nitriding. The article describes hardening for various types of cutting tools, namely, broaches, chasers, milling cutters, drills, taps, reamers, form tools, and hobs, and for thread rolling dies, threading dies, and bearings.

This article discusses the various elements of thread grinding processes, including thread grinding machines, tolerances, wheel selection, grinding speed, and grinding fluids. It describes truing of grinding wheels and reviews the process applications. In addition, the article describes the five basic methods employed for cylindrical thread grinding, namely, single-rib wheel traverse grinding, multirib wheel traverse grinding, multirib wheel plunge grinding, multirib wheel skip-rib, or alternate-rib, grinding, and multirib wheel three-rib grinding. It also provides an overview of centerless grinding of threads and high-volume applications of thread grinding.

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 discusses the effect of thread design, preload, tightening, and mean stress on the fatigue strength of bolt steel. It describes the factors influencing fatigue failures in cold-driven and hot-driven riveted joints. The factors affecting the fatigue resistance of bolted friction joints are also discussed. The article reviews stress concentrations in pin joints and discusses stress-intensity factors for mechanically fastened joints.

This article discusses the properties of threaded fasteners made from carbon and low-alloy steels containing a maximum of 0.55% carbon. It provides guidelines for the selection of steels for bolts, studs, and nuts intended for use at temperatures between -50 and 370 deg C. The article also discusses steels rated for service above 370 deg C and describes internationally recognized grade designations. The specifications provided can be used to outline fastener requirements, control manufacturing processes, and establish functional or performance standards. The most commonly used protective metal coatings for ferrous metal fasteners; zinc, cadmium, and aluminum; are described as well.

Diamond and cubic boron nitride (CBN) are the two hardest materials known. They have found numerous applications in industry, both as ultrahard abrasives and as cutting tools. This article reviews the high-pressure synthesis and fabrication techniques of these materials. It discusses their wear resistance, tool geometries, and machining parameters. The article also explains their application as cutting tools in the field of machining.

Tapping is a machining process for producing internal threads. This article provides a discussion on machines and accessories of tapping. It reviews the seven categories of taps, namely, solid, shell, sectional, expansion, inserted-chaser, adjustable, and collapsible taps, as well as their design and functions. It explains the influences of various factors on the selection of tap design features and discusses the principal factors that influence the selection of equipment and procedure for tapping. The article reviews the factors that determine torque demand. It also provides an overview of tap materials and surface treatment and concludes with a discussion on tapping of taper pipe threads.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of titanium alloys and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the fracture surface, fatigue crack growth, intergranular fracture, crack propagation, ductile overload fracture, dimpled rupture, microvoid coalescence, and quasi-cleavage fracture of these alloys.

Visual examination, using the unaided eye or a low-power optical magnifier, is typically one of the first steps in a failure investigation. This article presents the guidelines for selecting samples for scanning electron microscope examination and optical metallography and for cleaning fracture surfaces. It discusses damage characterization of metals, covering various factors that influence the damage, namely stress, aggressive environment, temperature, and discontinuities.

The machinability of stainless steels varies from low to very high, depending on the final choice of the alloy. This article discusses general material and machining characteristics of stainless steel. It briefly describes the classes of stainless steel, such as ferritic, martensitic, austenitic, duplex, and precipitation-hardenable alloys. The article examines the role of additives, such as sulfur, selenium, tellurium, lead, bismuth, and certain oxides, in improving machining performance. It provides ways to minimize difficulties involved in the traditional machining of stainless steels. The article describes turning, drilling, tapping, milling, broaching, reaming, and grinding operations on stainless steel. It concludes with information on some of the nontraditional machining techniques, including abrasive jet machining, abrasive waterjet machining electrochemical machining, electron beam machining, and plasma arc machining.

This article describes the influence of steel chemical compositions and microstructure on machining processes. It discusses the various microstructural phases of standard carbon and alloy steels, which influence machinability. The article reviews the expected response of several traditional machining operations, such as turning, drilling, milling, shaping, thread cutting, and grinding, to the microstructure of standard steel grades. It also explains the technologies in non-traditional machining processes, such as abrasive waterjet cutting, electrical chemical grinding, and laser drilling.

This article discusses the types and operations of the most common machines used for die threading. The construction, types, and comparison of solid and self-opening dies are discussed. The article explains the modification of chasers for threading Monel shaft. The principal factors that influence thread quality, production rate, and cost in die threading are composition and hardness of work metal; accuracy and finish; thread size; obstacles, such as shoulders or steps; speed; lead control; and cutting fluid. The article examines these factors and describes the tools and cutting fluids used for pipe threading along with the severity of stop lines.

This article compares and contrasts mechanical joining techniques used in the manufacture of aluminum assemblies, including seaming, swaging, flanging, crimping, clinching, dimpling, interference and snap fits, and interlocking joints. It provides basic illustrations of the various methods and summarizes the advantages and disadvantages of each. The article also discusses the use of staples, nails, rivets, and threaded fasteners and provides relevant property and performance data.

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 soft and ductile metal binder. The performance of cemented carbide as a cutting tool lies between that of tool steel and cermets. Almost 50% of the total production of cemented carbides is used for nonmetal cutting applications. Their properties also make them appropriate materials for structural components, including plungers, boring bars, powder compacting dies and punches, high-pressure dies and punches, and pulverizing hammers. This article discusses the manufacture, microstructure, composition, classifications, and physical and mechanical properties of cemented carbides, as well as their machining and nonmachining applications. It examines the relationship between the workpiece material, cutting tool and operational parameters, and provides suggestions to simplify the choice of cutting tool for a given machining application. It also examines new tool geometries, tailored substrates, and the application of thin, hard coatings to cemented carbides by chemical vapor deposition and physical vapor deposition. It discusses the tool wear mechanisms and the methods available for holding the carbide tool. The article is limited to tungsten carbide cobalt-base materials.

Metal is removed from the workpiece by the mechanical action of irregularly shaped abrasive grains in all grinding operations. This article discusses three primary components of grinding wheels, namely, abrasive (the cutting tool), bond (the tool holder), and porosity or air for chip clearance and/or the introduction of coolant. It describes the compositions and applications of coated abrasives and types of grinding fluids, such as petroleum-base and mineral-base cutting oils, water-soluble oils, synthetic fluids, semisynthetic fluids, and water plus additives. The article concludes with information on different types of grinding processes, namely, rough grinding, precision grinding, surface grinding, cylindrical grinding, centerless grinding, internal grinding, and tool grinding.

This article provides information on the operating principle, tool material and design changes, and safety and protection of various multifunction machines as well as the cutting fluids used. These include single-spindle automatic lathes, manual turret lathes, single-spindle automatic bar and chucking machines, Swiss-type automatic bar machines, multiple-spindle automatic bar and chucking machines, and multiple-spindle vertical chucking machines. The article provides examples that illustrate typical variations in dimensions obtained with a multiple-spindle machine. It also describes the machinability and provides information on the physical condition of the work metal. The article discusses the various factors to be considered in the selection of an appropriate machine. It presents examples that describe the techniques and equipment selected for specific production applications. In addition, the article discusses the types, applications, advantages, and disadvantages of machining centers and transfer machines. Finally, it provides the goals, objectives, and production techniques of flexible manufacturing systems.

This article discusses the development of a welding procedure for friction stir welding (FSW), including the process of defining a preliminary procedure, the optimization of parameters, the development of supporting data, and other key features to ensure a successful procedure. The critical features of FSW tool design, initial process parameters, systematic welding trials, and robustness testing are reviewed. The article provides information on the common features of welding procedure qualification. It also includes a table that lists the procedures used in the production of sound friction stir welds in various aluminum alloys.