The horsepower requirements to cut various metal alloys provide an indication of the relative ease and cost of machining, but several other important factors include cutting tool material, chip formation, cutting fluids, cutting tool wear, surface roughness, and surface integrity. This article reviews these general machining factors as well as specific cutting tool and cutting parameters for the six basic chip-forming processes of turning, shaping, milling, drilling, sawing, and broaching. Best practices for each of the six chip-forming processes are suggested for optimized machining of aluminum alloys. The article lists the inherent disadvantages of machining processes that involve compression/shear chip formation. It discusses the machining of aluminum metal-matrix composites and nontraditional machining of aluminum, such as abrasive jet, waterjet, electrodischarge, plasma arc, electrochemical, and chemical machining.

Machining of cast iron involves removing metal from the cast part, usually by cutting with a power-driven machine tool. This article discusses the factors that influence machinability, the methods used to evaluate machinability of cast irons, the effects of cast iron microstructure on cutting tool life, and the importance of as-cast surface integrity on the machining variation. It presents examples of cutting tool materials selection for different cast iron grades, and describes the effects of coolants on the machining of cast irons. A chart showing different cutting materials and cutting speed ranges for selected iron-carbon alloys is also presented. Different types of cutting tool wear observed during turning are schematically illustrated.

This article provides information on the infiltration mechanism of carbide structures. It reviews the basic techniques used for metal infiltration, including dip infiltration, contact filtration, gravity feed infiltration, and external-pressure infiltration. The article highlights various applications of contact infiltration in oil, gas, and blast-hole drilling such as fixed-cutter drill bits and diamond-impregnated coring bits. It also discusses the applications of infiltrated carbide material in erosion-resistant cladding.

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.

Shearing is a method for cutting a material piece into smaller pieces using a shear knife to force the material past an opposition shear knife in a progression form. This article describes the principles, attributes, and defects of straight-knife shearing. The equipment, materials used, and the operating parameters are discussed. The article provides information on the applications of rotary shearing. It concludes with a discussion on devices equipped with shearing machines for protecting personnel from the hazards of shear knives, flywheels, gears, and other moving parts.

Cemented carbides are extremely important in corrosion conditions in which high hardness, wear resistance, or abrasion resistance is required. This article describes the effect of binder composition and carbide addition on corrosion behavior of cemented carbides. It lists the examples of their uses in corrosion applications. The article provides information on the selection of cemented carbides for corrosion applications and tabulates the corrosion resistance of cemented carbides in various media. It expounds the oxidation resistance of cemented carbides and presents some tips to improve the properties of tungsten carbide cutting tools. The article also details the coating materials and coating processes of cemented carbides.

The applications of discontinuously reinforced ceramic-matrix composites (CMCs) fall into four major categories, namely, cutting tool inserts; wear-resistant parts; aerospace and military applications; and other industrial applications, including engines and energy-related applications. This article provides examples for these four categories, with an emphasis on those applications/materials that have achieved commercial viability. The applications for continuous fiber ceramic composites are also summarized.

This article describes the machining operations of carbon fiber-reinforced epoxy, or carbon/epoxy thermoset composite materials, such as drilling, reaming, routing, trimming, end milling, slot milling, and facing. It reviews cutting tools for machining, including solid carbide, diamond plated, brazed diamond, diamond coated carbide, and polycrystalline cutting tools. The article also describes cutting tool materials that are used for peripheral milling, face milling, and the trimming of polymer-matrix composites.

Good hole-drilling processes are key to joining composite parts with other composite parts or with metal parts. This article discusses the considerations for drilling polymer-matrix composites. It describes the use of power-feed drill motors and automated drilling/fastener installation equipment. The article provides a discussion on reaming, countersinking, and three recommended choices of cutting tools for producing a countersink in carbon/epoxy structure. The cutting tools include: standard carbide insert cutters, solid carbide cutters, or polycrystalline diamond (PCD) insert cutters. The article concludes with a discussion on inspection of hole quality.

Selecting the proper cutting tool material for a specific machining application can provide substantial advantages, including increased productivity, improved quality, and reduced costs. This article begins with a description of the factors affecting the selection of a cutting tool material. This is followed by a schematic representation of their relative application ranges in terms of machining speeds and feed rates. The article provides a detailed account of chemical compositions of various tool materials, including high-speed tool steels, cobalt-base alloys, cemented carbides, cermets, ceramics, cubic boron nitride, and polycrystalline diamond. It compares the toughness, and wear resistance for these cutting tool materials. Finally, the article explains the steps for selecting tool material grades for specific application.

This article is a comprehensive collection of machining data, presented in tables, covering most of the commonly used machining operations including turning, face milling, end milling (peripheral), drilling, reaming, and tapping of several materials. It provides starting recommendations for the range of speeds and feeds for various machining operations, parameters for the selection of tool geometry, and guidelines on the selection and identification of cutting fluids.

This article describes the relationship between failure analysis and materials selection and a basic procedure for performing a failure analysis. It discusses the methods for analyzing failures to improve materials selection and presents examples that illustrate the use of failure analysis in materials selection and materials development/refinement.

This article focuses on precision and ultraprecision finish machining techniques that make use of defined cutting edges, such as polycrystalline diamond and cubic boron nitride compacts. The techniques are finish turning, finish broaching, finish milling, and finish drilling.

The classes of tool materials for machining operations are high-speed tool steels, carbides, cermets, ceramics, polycrystalline cubic boron nitrides, and polycrystalline diamonds. This article discusses the expanding role of surface engineering in increasing the manufacturing productivity of carbide, cermet, and ceramic cutting tool materials used in machining operations. The useful life of cutting tools may be limited by a variety of wear processes, such as crater wear, flank wear or abrasive wear, builtup edge, depth-of-cut notching, and thermal cracks. The article provides information on the applicable methods for surface engineering of cutting tools, namely, chemical vapor deposited (CVD) coatings, physical vapor deposited coatings, plasma-assisted CVD coatings, diamond coatings, and ion implantation.

Mechanical cutting methods are widely used by the metal fabrication industry. This article introduces the welding fabricator to some of the mechanical equipment used to shape or prepare metals for welding. The most prevalent equipment used for mechanical cutting includes shears, iron workers, nibblers, and band saws. The article provides details on each of these.

Ceramic-metal composites, or cermets, combine the heat and wear resistance of ceramics with the formability of metals, filling an application niche that includes cutting tools, brake pads, heat shields, and turbine components. This article examines a wide range of cermets, including oxide cermets, carbide and carbonitride cermets, boride cermets, and other refractory types. It describes the powder metallurgy process by which cermets are produced, examining each step from powder preparation to post treatment. It discusses forming and compacting, injection molding, extrusion, rolling, pressing, slip casting, and sintering. It also discusses fundamental concepts such as chemical bonding, chemical composition, microstructure, and the development of physical and mechanical properties.

Synthetic diamond and cubic boron nitride are among a class of superhard materials from the boron-carbon-nitrogen-silicon family of elements. This article focuses on the two materials, the forms in which they are produced, and their respective properties. Synthetic diamond and cubic boron nitride compounds are available in the form of grit and sintered polycrystalline blanks of various size, shape, and composition. The article explains how superabrasive grains made from these materials can be used in lapping, polishing, and grinding applications, and how diamond and boron nitride blanks can be mounted to suitable substrates to form ultrahard cutting edges and tools.

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.

Shaped tube electrolytic machining (STEM) is a modified electrochemical machining (ECM) process that uses an acid electrolyte so that the removed metal goes into the solution instead of forming a precipitate. This article lists some specific machining applications of the STEM process, including turbine blade cooling holes, turbine vane cooling holes, turbine disk cooling passages, oil passages, and fuel nozzles. It describes the limitations and advantages of the STEM process. The article discusses the various tool parts of the STEM system, including the holding fixture, guide for cathodes, cathodes, and cathode holder/manifold. The article concludes with information on the process parameters of the STEM system.

Thread milling is a method of cutting screw threads with a milling cutter in a thread mill. This article discusses the operational procedures of thread milling machines, namely, universal thread mills, production thread mills, planetary thread mills, and numerical control machines. It describes the classification of thread milling cutters, such as single-form cutters and multiple-form cutters. The article reviews the speeds and feeds for thread milling, which depend on a number of variables, such as the material being milled, tool material, and rigidity of the machine and workpiece. It tabulates the cutting speeds for climb and conventional milling.