Aluminum casting in steel and iron permanent molds is used widely throughout industry, and the vast majority of permanent mold castings are made of aluminum and its alloys. There are several methods used to cast aluminum in permanent molds. This article focuses on permanent mold casting with molten aluminum fed by gravity, low pressure, vacuum and centrifugal pressure, and squeeze casting. It discusses the major variables that affect the life of permanent molds, including pouring temperature, casting shape, cooling methods, heating cycles, storage, and cleaning. The article reviews the basic components of mold coatings: refractory fillers, binder, and carrier. Casting defects and suggested corrective actions for permanent mold casting are summarized in a table. The article concludes with a discussion on thin-wall permanent-mold castings.

This article describes the applications, advantages, and disadvantages of three centrifugal casting processes as well as the equipment used. These processes are true centrifugal casting, semicentrifugal casting, and centrifuge mold casting. The article discusses the cooling, inoculation, fluxing, and extraction of castings. It reviews mold heating and coating techniques as well as the various molds used. The three most common defects observed in centrifugal castings are also discussed. The article concludes with information on the applications of centrifugal casting in investment casting and combustion synthesis as well as spin casting.

Aluminum casting alloys are among the most versatile of all common foundry alloys and generally have high castability ratings. This article provides an overview of the common methods of aluminum shape casting. It discusses the designations of aluminum casting alloys categorized by the Aluminum Association designation system. The article summarizes the basic composition groupings of aluminum casting alloy and discusses the effects of specific alloying elements and impurities. The characteristics of the important casting processes are summarized and compared in a table. The article presents the advantages and disadvantages of green sand casting, permanent mold casting, semipermanent mold casting, and high-pressure die casting. A discussion on other casting processes, such as investment casting, lost foam, plaster mold casting, pressure casting, centrifugal casting, and semisolid casting, is also included.

This article discusses the general principles and advantages of countergravity mold filling. It details several production implementations that use differential pressure countergravity mold filling methods, namely the countergravity low-pressure air process, countergravity low-pressure vacuum process, countergravity low-pressure inert atmosphere process, countergravity pressure vacuum process, supported shell technique, loose sand vacuum process, and countergravity centrifugal casting process.

In general, metal-matrix composites (MMCs) are classified into three broad categories: continuous fiber-reinforced composites, discontinuous or short fiber-reinforced composites, and particle-reinforced composites. This article focuses on stir casting and melt infiltration as the two main methods of MMC solidification processing. It describes the MCC casting methods, such as sand and permanent mold casting, centrifugal casting, compocasting, and high-pressure die casting. The article discusses the MMC infiltration processes in terms of pressure infiltration casting and liquid metal infiltration. It reviews the powder metallurgy processing of aluminum MMCs and deformation processing of discontinuously reinforced aluminum composites. The article concludes with a discussion on the processing of fiber-reinforced aluminum.

Horizontal centrifugal casting is used to cast parts having an axis of revolution. This article discusses the operations of three types of horizontal casting machine: the flanged shaft machine, the horizontal roller-type machine, and the double-face plate machine. It provides information on expendable and permanent molds used for centrifugal casting. The parameters and operations of the horizontal centrifugal casting process, including pouring and solidification, as well as the applications are described.

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 focuses on the general root causes of failure attributed to the casting process, casting material, and design with examples. The casting processes discussed include gravity die casting, pressure die casting, semisolid casting, squeeze casting, and centrifugal casting. Cast iron, gray cast iron, malleable irons, ductile iron, low-alloy steel castings, austenitic steels, corrosion-resistant castings, and cast aluminum alloys are the materials discussed. The article describes the general types of discontinuities or imperfections for traditional casting with sand molds. It presents the international classification of common casting defects in a tabular form.

Vertical centrifugal casting machines, installed below the ground level for maximum operator safety, are used for producing bushings and castings that are relatively large in diameter and short in length. This article discusses the mold design for different types of sand molds and permanent molds and their production considerations. It describes the speed of rotation, mold speeds curves, and pouring techniques that are considered in the operation of vertical centrifugal casting machines.

Skull melting refers to the use of furnaces with water-cooled crucibles that freeze a solid “skull” of material on the crucible wall. This article describes the basic components, operating pressure, advantages, and applications of vacuum arc and induction skull melting furnaces.

Metal matrix composites (MMCs) can be synthesized by vapor phase, liquid phase, or solid phase processes. This article emphasizes the liquid phase processing where solid reinforcements are incorporated in the molten metal or alloy melt that is allowed to solidify to form a composite. It illustrates the three broad categories of MMCs depending on the aspect ratio of the reinforcing phase. The categories include continuous fiber-reinforced composites, discontinuous or short fiber-reinforced composites, and particle-reinforced composites. The article discusses the two main classes of solidification processing of composites, namely, stir casting and melt infiltration. It describes the effects of reinforcement present in the liquid alloy on solidification. The article examines the automotive, space, and electronic packaging applications of MMCs. It concludes with information on the development of select cast MMCs.

This article describes typical foundry practices used to commercially produce zirconium castings. The foundry practices are divided into two sections, namely, melting and casting. The article discusses various melting processes, such as vacuum arc skull melting, induction skull melting, and vacuum induction melting. Various casting processes, such as rammed graphite casting, static and centrifugal casting, and investment casting are reviewed. The article also provides information on the mechanical and chemical properties of zirconium castings.

Babbitting is a process by which relatively soft metals are bonded chemically or mechanically to a stronger shell or stiffener which supports the weight and torsion of a rotating, oscillating, or sliding shaft. This article focuses on workpiece preparation and babbitting methods. Prior to casting, the workpiece must be scrupulously prepared by various cleaning, fluxing, and tinning steps. Babbitting of bearing shells can be accomplished by three methods, namely, static babbitting, centrifugal casting, and metal spray babbitting.

Mechanical cleaning systems are used to remove contaminants of work surface by propelling abrasive materials through any of these three principal methods: airless centrifugal blast blade- or vane-type wheels; compressed air, direct-pressure dry blast nozzle systems; or compressed-air, indirect-suction (induction) wet or dry blast nozzle systems. This article focuses on the abrasive media, equipment, applications, and limitations of dry and wet blast cleaning. It discusses the health and safety precautions to be taken during mechanical cleaning.

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.

After solidification and cooling, further processing and finishing of the castings are required. This article describes the general operations of shakeout, grinding, cleaning, and inspection of castings, with particular emphasis on automation technology. It illustrates the vertical core knockout machine and the A-frame core knockout machine and lists the advantages and disadvantages of these machines. The article describes the general factors in automated or manual gate removal process. It concludes with discussion on the various types of inspection, such as the liquid penetrant inspection, pressure testing, radiographic inspection, magnetic particle inspection, and ultrasonic inspection.

Investment casting, in which molten metal is poured into hot molds, allows for the production of aluminum parts with extremely thin sections, knife edges and sharp detail. This article describes the various steps in the investment casting process, including patternmaking and dimensioning, the design and manufacture of shell molds, melting and casting methods, and postcasting operations such as knockout, core removal, and cleaning. It also addresses a wide range of design considerations, discusses casting defects, and provides several design examples.

Aggregate molding, or sand casting, is the gravity pouring of liquid metal into a mold that is made of a mixture molded against a permanent pattern. This article summarizes the most important materials in the process of sand casting of cast iron, including different types of molding aggregates, clays, water, and additives in green sand, chemically bonded organic resins, and inorganic binders in self-setting, thermosetting, and gas-triggered systems. It discusses three main types of reclamation systems: wet, dry, and thermal. The article concludes with a description of both nonpermanent and permanent mold processes.