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.

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.

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.

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.

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.

This article provides an overview of the independent and dependent variables of a machining process. Independent variables include workpiece material, specific machining processes, and tool materials and geometry. Cutting force and power, surface finish, and tool wear and failure are some dependent variables discussed. The article also describes the relations between the input variables and process behavior.

Abrasive jet machining (AJM) is a process that removes material from a workpiece through the use of abrasive particles entrained in a high-velocity gas stream. This article discusses the operation of principal components, advantages, and disadvantages of the AJM system. It describes several factors that determine the characteristics of the AJM process. These include flow rates of the jet stream, type and size of abrasive powders, and distance between the workpiece and nozzle.

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.

A fixture is a special workholding and supporting device designed and built for a particular part or shape that can be made by using standardized components, such as drill bushings, locating buttons, and clamping devices. This article provides a discussion on optimum fixture design and describes the clamping methods, namely, manual clamping, pneumatic clamping, and hydraulic clamping, and their specific principles. It presents an overview on modular fixturing for limited production. The article concludes with information on cost factors in fixturing.

The relative motion between the tool and the workpiece during cutting compresses the work material near the tool and induces a shear deformation that forms the chip. This article discusses the fundamental nature of the deformation process associated with machining. It describes the mechanics of the machining process, and presents the principles of the orthogonal cutting model. The article also analyzes the effect of workpiece properties on chip formation.

This article discusses the mechanics of chip formation and reviews the analytical modeling of the chip formation process by high-speed machining within the framework of continuum mechanics. It examines the relationship between the various high-speed machining parameters. The article describes the cutting tool systems for aluminum alloys, steel, superalloys, and titanium alloys and provides an overview of the alternative cutting tool geometries for increasing tool life. It highlights the factors considered by companies planning to employ high-speed machining systems and concludes with information on the applications of high-speed machining.

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.