The Replicast process is developed to overcome the formation of lustrous carbon defects and carbon pickup observed in conventional evaporative pattern casting processes. This article provides a discussion on the pattern production, process capabilities, advantages, and limitations of Replicast process.

Lost foam casting is a sand casting process in which the mold consists of an evaporative polystyrene foam pattern embedded in sand. It is especially well suited for making complex parts with convoluted features such as engine blocks, transmission cases, and cylinder heads. This article describes the lost foam casting process and its primary advantages, including the elimination of flash and parting lines, the relative ease of prototyping with foam, and the ability to incorporate multiple metals, whether in sections or layers, through sequential pours. It illustrates an entire process cycle from mold filling to fusion, cooling, and part ejection. The article also provides information on casting quality, discussing dimensional tolerances, fold defects, and porosity.

This article discusses the sequence of operations for producing a foam pattern for casting. It provides information on expandable polystyrene, the most preferred material for manufacturing lost foam patterns. The article then describes the major functions of pattern molding and assembly. The types and application methods of various lost foam coatings are explained. The article also describes the investment of the foam pattern in a sand system. It concludes with a discussion on the advantages of lost foam casting and information on the formation and control of folds.

Aluminum casting alloys are the most versatile of all common foundry alloys and generally have the highest castability ratings. This article discusses the designation and classification of aluminum casting alloys based on their composition and the factors influencing alloy selection. Alloys discussed include rotor alloys, commercial duralumin alloys, premium casting alloys, piston and elevated-temperature alloys, general-purpose alloys, magnesium alloys, aluminum-zinc-magnesium alloys, and bearing alloys. Six basic types of aluminum alloys developed for casting include aluminum-copper, aluminum-copper-silicon, aluminum-silicon, aluminum-magnesium, aluminum-zinc-magnesium, and aluminum-tin. The article also describes the main casting processes for aluminum alloys, which include die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, and investment casting. In addition, the article discusses factors affecting the mechanical and physical properties, microstructural features that affect mechanical properties, the effects of alloying, and major applications of aluminum casting alloys.

Aluminum casting alloys are the most versatile of all common foundry alloys and generally have the highest castability ratings. This article provides an overview of the common methods of aluminum shape casting. These include gravity casting, die casting, sand casting, lost foam casting, shell mold casting, plaster casting, investment casting, permanent mold casting, squeeze casting, semisolid forming, centrifugal casting, and pressure die casting. The article presents several different factors on which the selection of a casting process depends. It discusses gating and risering principles in casting. The article concludes with information on premium engineered castings that provide higher levels of quality and reliability than in conventionally produced castings.

This article discusses classification of foundry processes based on the molding medium, such as sand molds, ceramic molds, and metallic molds. Sand molds can be briefly classified into two types: bonded sand molds, and unbonded sand molds. Bonded sand molds include green sand molds, dry sand molds, resin-bonded sand molds, and sodium silicate bonded sand. The article describes the casting processes that use these molds, including the no-bake process, cold box process, hot box process, the CO2 process, lost foam casting process and vacuum molding process. The casting processes that use ceramic molds include investment casting, and plaster casting. Metallic molds are used in permanent mold casting, die casting, semisolid casting, and centrifugal casting.

Green sand molding and chemically bonded sand molding are considered to be the most basic and widely used mold-making processes. This article describes the sand system formulation, preparation, mulling, mold fabrication, and handling of green sand molds. It lists the advantages and disadvantages of green sand molding. The article discusses the primary control parameters for the sand system formulation. It describes two basic types of green sand molds: flask molds and flaskless molds. The article provides a discussion on molding problems, including springback and expansion defects. It considers a variety of sand reclamation systems, including wet washing/scrubbing and thermal-calcining/thermal-dry scrubbing combinations.

The additive manufacturing technologies in the casting of precious metals are divided into two groups: indirect metal methods and direct metal methods. Besides providing a process overview of both of these methods, the focus of this article is on the characteristics, process steps, applications, and advantages of direct metal methods, namely laser melting, material extrusion, binder jetting, material jetting, and vat photopolymerization methods.

This article reviews the basic types of mold aggregates and bonding methods for expendable molds and coremaking. It provides an overview of mold media and the basic types of sands and their properties. The most significant clays used in green sand operations, such as bentonites, are discussed. The article describes the methods of sand bonding with inorganic compounds. It provides a description of resin-bonded sand systems: no-bake binder systems, heat-cured binder systems, and cold box binder systems. The article concludes with a discussion on the media used for expendable molds, namely, ceramic shells and rammed graphite, for casting reactive metals such as titanium or zirconium.

Aluminum casting alloys are the most versatile of all common foundry alloys and generally have the highest castability ratings. Aluminum alloy castings are routinely produced by pressure-die, permanent-mold, green and dry-sand, investment, and plaster casting. This article describes factors affecting the selection of casting process and the general designation system for aluminum alloys. It provides useful information on mechanical test methods, selection of proper test specimens for accurate test methods, characteristics of premium engineered castings, and advantages of hot isostatic pressing.

This article outlines the beam/sample interactions and the basic instrumental design of a scanning electron microscopy (SEM), which include the electron gun, probeforming column (consisting of magnetic electron lenses, apertures, and scanning coils), electron detectors, and vacuum system. It discusses the contrasts mechanisms used for imaging and analyzing materials in the SEM. These include the topographic contrast, compositional contrast, and electron channeling pattern and orientation contrast. Special instrumentation and accessory equipment used at elevated pressures and during the X-ray microanalysis are reviewed. The article also provides information on the sample preparation procedure and the materials applications of the SEM.

The purpose of fractography is to analyze fracture features and attempt to relate the topography of the fracture surface to the causes and/or basic mechanisms of fracture. This article reviews the historical development of fractography, from the early studies of fracture appearance dating back to the sixteenth century to the state-of-the-art work in electron fractography and quantitative fractography. It also describes the applications and limitations of scanning electron microscope and transmission electron microscope.

This article discusses slurry molding that encompasses two distinct processes: plaster molding and ceramic molding. Plaster mold casting is a specialized casting process used to produce nonferrous castings that have greater dimensional accuracy, smoother surfaces, and more finely reproduced detail. The article describes three generally recognized plaster mold processes, namely, conventional plaster mold casting, the Antioch process, and the foamed plaster process. Ceramic molding techniques are based on processes that employ permanent patterns and fine-grained zircon and calcined, high-alumina mullite slurries for molding. The Shaw process and the proprietary Unicast processes are also discussed.

Electron beam melting includes melting, refining, and conversion processes for metals and alloys. This article describes the electron beam melting process, as well as the principles, equipment, and process considerations of drip melting and cold hearth melting process.

No-bake sand molds are based on the curing of inorganic or organic binders with either gaseous catalysts or liquid catalysts. This article reviews the major aspects of no-bake sand bonding in terms of coremaking, molding methods, and sand processing. It discusses the points to be noted in handling sand-resin mixtures for no-bake molds or cones and lists some advantages of no-bake air-set cores and molds. The article describes the process procedures, advantages, and disadvantages of gas curing and air-setting hardening of sodium silicates. It examines the members of the air-setting organic binders, namely, furan no-bake resins, phenolic no-bake resins, and urethanes. The article provides an overview of gas-cured organic binders. It also illustrates the three commercial systems for sand reclamation: wet reclamation systems, dry reclamation systems, and thermal reclamation.

Macroetching is a procedure for revealing the large-scale structure of a metallic specimen, that is, the structure visible with the unaided eye, by etching an appropriately prepared surface. This article provides information on the basic procedures for macroetching as well as the apparatus used. It discusses selected etchants for efficient macroetching of various metals and their alloys, including iron, steel, high-alloy steels, stainless steels, high-temperature alloys, titanium, titanium alloys, aluminum, aluminum alloys, copper, and copper alloys. The article also describes various conditions that are revealed by the macroetching of aluminum.

The initial cast superalloy developments in the United States centered on cobalt-base materials. Nickel-base and nickel-iron-base superalloys owe their high-temperature strength potential to their gamma prime content. For polycrystalline superalloy components, high-temperature strength is affected by the condition of the grain boundaries and, in particular, the grain-boundary carbide morphology and distribution. Vacuum induction melting offers more control over alloy composition and homogeneity than all other vacuum melting processes. The primary purification reaction occurring in the process is the removal of melt contained oxygen by means of a reaction with carbon to form carbon monoxide. A number of casting processes can provide near-net shape superalloy cast parts, but essentially all components are produced by investment casting. The solidification of investment cast superalloy components is precisely controlled so that the microstructure, which ultimately determines mechanical properties, remains consistent. Heat treating cast superalloys involves homogenization and solution heat treatments or aging heat treatments.

Cores are separate shapes of sand that are placed in the mold to provide castings with contours, cavities, and passages that are not otherwise practical or physically obtainable by the mold. This article describes the basic principles of coremaking and the types of core sands, binders, and additives used in coremaking. It discusses the curing of compacted cores by core baking and the hot box processes. The article provides an overview of the core coatings, assembling and core setting, coring of tortuous passages, and cores in permanent mold castings and investment castings. It also discusses the design considerations in coremaking to eliminate cores and compares coring with drilling.