This article reviews the main theoretical and practical aspects of sequence normally followed in digital image-acquisition, processing, analysis, and output for material characterization. It discusses the main methods of digital imaging, image processing, and analysis, as applied to microscopy of materials. The article describes the basic concepts of sampling and resolution and quantization of light microscopy, scanning electron microscopy, and transmission electron microscopy. It discusses the acquisition of a digital image that accurately represents the sample under observation and output of the image to a printer. The methods used to enhance the digital image and to extract quantitative information are also described. Different types of image segmentation, namely, adaptive segmentation and contour-based segmentation, are reviewed. The article also presents case studies on the application of image processing and analysis to materials characterization.

Efforts in improving the efficiency of automated equipment lead to combining automatic joining equipment with a modem computer technique eventually known as artificial intelligence (intelligent automation) that usually includes an off-line planning system and a real-time adaptive control system connected through a computer communications interface. This article focuses on the application of intelligent automation system to arc welding, called WELDEXCELL, and other joining processes. An outline of the interface between off-line planners and real-time control systems is also provided.

This article discusses the evolution of computer numerical control and direct numerical control for machine tools. It describes the fundamentals and advantages of numerical control (NC) systems. The article reviews the manual or computer assisted off-line programming methods for programming the tools with the aid of the automatically programmed tool language. It also explains point-to-point and continuous-path or contouring of NC systems and the adaptive systems used for NC.

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.

In the metal producing and processing industries, induction melting and holding has found wide acceptance. This article provides a detailed account of the physical principles of induction melting processes. It discusses the fundamental principles and components of induction furnaces such as induction crucible furnaces, channel induction furnaces, and induction furnaces with cold crucible. The article describes the advantages, applications, and fundamental principles of induction skull melting. It also provides information on the various specific application-designed induction melting installations.

This article provides information on metals that can be cast in permanent molds. It describes the advantages, disadvantages, applications, and design of permanent castings. Following a discussion on the factors considered in mold design and material selection, the article details the application of mold coatings and examines the effects of major processing variables on mold life. The variables that determine mold temperature and measures for controlling it are reviewed, and the effects of short-term and long-term variables on the dimensional accuracy of permanent mold castings are explained. The article concludes with a discussion on the factors influencing the surface finish on permanent mold castings.

This article reviews the essential parts of the complex process of quantitative image analysis to assist automatic image analysis in laboratories. It describes the basic difference between the bias of classical manual stereological analysis and quantitative image analysis. The article concentrates on the basic properties of digital measurements that are the core of quantitative image analysis. It provides a brief description of the specimen and apparatus preparation as well as the image acquisition. The article explains how to evaluate stereological parameters and provides the general rules and guidelines for optimization of image processing algorithms from the viewpoint of shape quantification. It concludes with examples that demonstrate the usefulness of automatic image analysis in comparison to manual methods.

Stretch forming is the forming of sheet, bars, and rolled or extruded sections over a die or form block of the required shape while the workpiece is held in tension. This article discusses the applicability, advantages, and machines and accessories of stretch forming. It provides a detailed discussion on four methods of stretch forming, namely, stretch draw forming, stretch wrapping, compression forming, and radial draw forming.

This article covers in-line process monitoring of the metal additive manufacturing (AM) methods of laser and electron beam (e-beam) powder-bed fusion (PBF) and directed-energy deposition (DED). It focuses on methods that monitor the component directly throughout the build process. This article is organized by the type of AM process and by the physics of the monitoring method. The discussion covers two types of monitoring possible with the PBF process: monitoring the area of the powder bed and component and monitoring the melt pool created by the laser or e-beam. Methods for layer monitoring include optical and thermal methods that monitor light reflected or emitted in the visible and infrared wavelengths, respectively. Monitoring methods for laser directed-energy deposition (DED) discussed are those that measure the size and shape of the melt pool, the temperature of the melt pool, and the plasma generated by the laser as it interacts with the molten metal.

This article reviews the characterization methods for producing 3-D microstructural data sets. The methods include serial sectioning by mechanical material removal method and focused ion beam tomography method. The article describes how these data sets are used in realistic 3-D simulations of microstructural evolution during materials processing and materials response. It also explains how the 3-D experimental data are actually input and used in the simulations using phase-field modeling and finite-element modeling.

This article discusses the various categories of nontraditional machining processes that are subdivided according to the form of energy being harnessed. These include mechanical, electrical, thermal, and chemical methods.

Machine vision, also referred to as computer vision or intelligent vision, is a means of simulating the image recognition and analysis capabilities of the human eye and brain system with digital techniques. The machine vision functionality is extremely useful in inspection, supervision, and quality control applications. This article presents a variety of machine vision functions for different purposes and provides a comparison of machine and human vision capabilities in a table. It discusses the processes of a machine vision system: image acquisition, image preprocessing, image analysis, and image interpretation. The article provides information on the uses of machine vision systems in three categories of manufacturing applications: visual inspection, identification of parts, and guidance and control applications.

A computational tool would require the contribution of the strengthening mechanisms of metallic material to be predicted and then summed in an appropriate way to derive an estimate of the tensile properties. This article focuses on the modeling of deformation mechanisms pertinent to structural materials, namely, solid-solution strengthening, age/precipitation hardening, dispersion strengthening, grain size reduction, strengthening from cold work, and strengthening from interfaces. It explains the application of predictive models in the atomistic modeling of dislocation structures and cast aluminum property prediction. The article concludes with information on the use of rules-based approaches and data-mining techniques for quantitative predictions of tensile properties.

The plasma carburizing process is basically a low-pressure carburizing process making use of a high-voltage electrical field applied between the load to be treated and the furnace wall producing activated and ionized gas species responsible for carbon transfer to the workpieces. This article begins with an overview of the theoretical background and the range and limitations of glow-discharge plasma. It describes the plasma carburizing process, which is carried out with methane or propane. Plasma carburizing processes of sinter metals and stainless steels, and the influence of current pulse length on carbon input of low-pressure carburizing process are also described. The article presents the basic requirements and process parameters to be considered in plasma carburizing equipment. It also exemplifies a still-working plasma process in industrial measure.

Ultrasound is an ideal modality for nondestructive evaluation (NDE) because it enables the interior of objects to be assessed without the safety and access issues associated with radiography. This article summarizes the history of array usage in NDE and its relationship to medical applications. It discusses the mathematics behind classical beamforming, full matrix capture, and total focusing methods of imaging. The article shows how ultrasonic array data can be simulated by direct numerical methods (most commonly using finite-element methods), analytical methods, or hybrid methods. It also considers various methods of comparing the performance of arrays and imaging algorithms. The article provides a comparison of various advanced and nonlinear imaging algorithm and looks at some practical industrial applications of arrays. It concludes with some future perspectives for arrays in NDE.

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.

Ring rolling is a process for creating seamless ring shaped components using specialized equipment and forming processes. This article provides information on the applications of ring rolling. It discusses the types of machines used for ring rolling, namely, vertical rolling machines, radial-axial horizontal rolling machines, four-mandrel mechanical table mills, three-mandrel table mills, and automatic radial-axial multiple-mandrel ring mills. The article provides a discussion on the process control technology and ancillary operations of ring rolling. It describes the methods of producing ring blanks and the various types of blanking and rolling tools used in ring rolling process. The article concludes with a discussion on rolled ring tolerances and machining allowances.

This article provides an overview of curing techniques, adhesive chemistries, surface preparation, adhesive selection, and medical applications of adhesives. The curing techniques are classified into moisture, irradiation, heat, and anaerobic. The article highlights the common types of curable adhesives used for medical device assemblies, including acrylics, cyanoacrylates, epoxies, urethanes, and silicones. Other forms of adhesives, such as hot melts, bioadhesives, and pressure-sensitive adhesives, are also discussed. The typical characteristics and applications of biocompatible medical device adhesives are listed in a table. The article concludes with a section on the selection of materials for medical adhesives.

This article discusses the principle, coil design, types and operation of a vacuum induction furnace. It describes the operation parameters that should be considered during the functioning of the induction furnace.

Powder-bed additive manufacturing (AM) processes are some of the most commonly used techniques, necessitating the accurate measurement of powder flowability properties. This article discusses some powder flow tests that occur in powder-bed AM machines. These include the Hall/Carney flow test, bulk/tap density, rheometer, and the revolving or rotating drum technique. The three categories of powder properties that are available from rheometer experiments are discussed: bulk, dynamic flow, and shear properties. The article also describes the basic principles and applications of micro-X-ray computed tomography in studying powder porosity characteristics nondestructively.