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.

Milling of materials, whether hard and brittle or soft and ductile, is of prime interest and of economic importance to the powder metallurgy (PM) industry. This article discusses the principles of milling, milling parameters, and the powder characteristics required for the process. It discusses the changes in powder particle morphology that occur during milling of metal powders produced by various processes such as microforging, fracturing, agglomeration, and deagglomeration. The article also provides useful information on milling equipment such as tumbler ball mills, vibratory ball mills, attrition mills, and hammer and rod mills.

Various powder production processes allow precise control of the chemical composition and physical characteristics of powders and allow tailoring of specific attributes for targeted applications. Metal powders are produced by either mechanical methods or chemical methods. The commonly used mechanical methods include water and gas atomization, milling, mechanical alloying, and electrolysis. Some chemical methods include reduction of oxides. This article provides information on the reliable techniques for powder characterization and testing to evaluate the chemical and physical properties of metal powders, both as individual particles and in bulk forms.

Nanotechnology and smart-coating technologies have been reported to show great promise for improved performance in critical areas such as corrosion resistance, durability, and conductivity. This article exemplifies nanofilms and nanomaterials used in coatings applications, including carbon nanotubes, silica, metals/metal oxides, ceramics, clays, buckyballs, graphene, polymers, titanium dioxide, and waxes. These can be produced by a variety of methods, including chemical vapor deposition, plasma arcing, electrodeposition, sol-gel synthesis, and ball milling. The application of nanotechnology and the development of smart coatings have been dependent largely on the availability of analytical and imaging techniques such as Raman spectroscopy, scanning and transmission electron microscopy, atomic force microscopy, and scanning tunneling microscopy.

This article discusses three types of powder-feeder systems that are commonly used throughout the thermal spray (TS) industry: gravity-based devices, rotating wheel devices, and fluidized-bed systems. It provides information on the various mechanical methods for producing powders, namely, crushing, milling, attriting, and machining. The article describes two prime methods of agglomeration. One method uses a binder by way of agglutination, while the other relies on a sintering operation. The article discusses the technology and principles of the processes that relate to thermal spraying, and offers an understanding for choosing particular feedstock materials that are classified based on the thermal spray process, material morphology, chemical nature of the material, and applications. Sieving, the most common method of separating powders into their size fractions, is also reviewed. The article also provides information on the topical areas and precautions to be undertaken to protect the operator from safety hazards.

The combination of high strength-to-weight ratio, excellent mechanical properties, and corrosion resistance makes titanium the best material choice for many critical applications. This article begins with a description of the historical perspective of titanium casting technology. It discusses the types of molding methods, such as rammed graphite molding and lost-wax investment molding. The article provides information on the casting design, melting, postcasting, and pouring practices. It describes the microstructure and mechanical properties of Ti-6AI-4V alloy. The article examines the product applications of titanium alloy castings. The tensile properties, standard industry specifications, and chemical compositions of various titanium alloy castings are tabulated.

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.

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 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 combination of high strength-to-weight ratio, excellent mechanical properties, and corrosion resistance makes titanium the best material choice for many critical applications. This article commences with a description of the historical perspective of titanium casting technology. It discusses the various types of molding methods, namely, rammed graphite molding, and lost-wax investment molding. The article provides information on the casting design, melting, and pouring practices, and describes the microstructure, hot isostatic pressing, heat treatment, and mechanical properties of Ti-6AI-4V alloy. It also talks about the chemical milling and weld repair, and describes the product applications of titanium alloy castings. Tensile properties, standard industry specifications, and chemical compositions of various titanium alloy castings are tabulated.

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.

Planing is a machining process for removing metal from surfaces in horizontal, vertical, or angular planes. This article discusses the process capabilities of planing and the operations of double-housing and open-side planers. It reviews workpiece setup procedures, including platelike workpieces, irregularly shaped workpieces, and workpieces used for tandem planning. The article provides information on the applications of high-speed steels and carbides in planer tools. It analyzes the tools available in a variety of configurations suited to the undercutting, slotting, and straight planing of either horizontal or vertical surfaces. These include carbide roughing, finishing, gooseneck-holder finishing, and double-cutting tools. The article lists recommended speeds and feeds for planing with high-speed steel or carbide tools. It concludes with a comparison of planing with sawing and milling.

Nickel-base alloys can be machined by techniques that are used for iron-base alloys. This article discusses the effects of distortion and microstructure on the machinability of nickel alloys. It tabulates the classification of nickel alloys based on machining characteristics. The article describes the machining operations performed on nickel alloys, such as turning, planing and shaping, broaching, reaming, drilling, tapping and threading, milling, sawing, and grinding. It provides information on the cutting fluids used in the machining of nickel alloys. The article also analyzes nontraditional machining methods that are suitable for shaping high-temperature, high-strength nickel alloys. These include electrochemical machining, electron beam machining, and laser beam machining.

This article describes the basic concepts of the complex factors that influence the forces, power, and stresses in machining. It provides an overview of the models of orthogonal (that is, two force) machining of metals as they are useful for understanding the basic mechanics of machining and can be extended for modeling of the production processes. The article discusses stresses on the shear plane, stresses distributions on the rake face, uniform stresses on the rake face, and nonuniform stress distributions on the rake face. It also examines the specific power consumption in turning, drilling, and milling operations. The article concludes with a section on the factors affecting specific power.

This article focuses on the machining of reactive metals which refer collectively to the elements titanium, hafnium, and zirconium. It provides guidelines for machining titanium and titanium alloys and describes machining operations, such as turning, milling, drilling, tapping, reaming, grinding, and sawing, performed on titanium and its alloys. The article also provides information on electrochemical machining (ECM), chemical milling (CHM), and laser beam machining (LBM) for titanium and titanium alloys. Guidelines for machining zirconium alloys and hafnium are also provided. The article provides a short description of turning, milling, and drilling operations performed on zirconium alloys and hafnium. It also discusses health and safety considerations related to zirconium and hafnium.

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 various machining techniques of refractory metals, namely, niobium, molybdenum, tantalum, and tungsten. These include turning, boring, trepanning, reaming, milling, tapping, drilling, and sawing. Parameters for the machining of the refractory metals are also tabulated. In addition, the article provides information on cutting fluids and tools that are used in machining of the refractory metals as well as on the safety precautions to be followed in the machining process.

This article discusses the types of adaptive control (AC) systems for metal cutting according to the AC strategies used. These include adaptive control with optimization (ACO), adaptive control with constraints (ACC), and geometric adaptive control (GAC). The article details the milling and grinding systems based on the ACO strategy. It reviews the fundamentals of ACC systems followed by a description of a particular ACC system for a turning operation. The article also describes the basic characteristics of GAC systems and presents a particular GAC system for the turning of cylindrical parts. It examines the issues in the AC systems such as tool wear/breakage. Trends in the AC systems such as variable-gain ACC systems and integration of adaptive control into CAD/CAM/CIM systems are also discussed.

The ultrasonic machining (USM) process consists of two methods, namely, ultrasonic impact grinding and rotary USM. This article lists the major ultrasonic components that are similar to both rotary USM and ultrasonic impact grinding. It also provides schematic representations of the components used in rotary USM and ultrasonic impact grinding. The article describes the operations of the components of the rotary ultrasonic machine and ultrasonic impact grinding machine. It discusses the applications of the rotary ultrasonic machine: drilling, milling, and surface grinding. The article concludes with information on machining characteristics of ultrasonic impact grinding.