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.

Injection molding is a process of forcing or injecting a fluid plastic material into a closed mold. The process generally has the advantages of being more readily automated and of permitting finer part details. Injection-molding compounds are thermoplastic or thermosetting materials and their composites that are specifically formulated for the injection-molding process. This article discusses the injection molding process, which includes the two basic categories of thermoplastic and thermoset injection molding, and lists the common thermoplastic and thermoset molding compounds and applications. It also describes the operation of the different types of injection molding machines as well as mold design and process controls. The article also describes the selection of injection-moldable thermosets, and provides an overview of part performance, properties, blowing agents, and aesthetic concerns related to thermoplastic structural-foam injection molding.

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 such as flask molds and flaskless molds. The article provides a discussion on molding problems including springback and expansion defects. It discusses a variety of sand reclamation systems, including wet washing/scrubbing and thermal-calcining/thermal-dry scrubbing combinations.

This article provides information on metals that can be cast in permanent molds. It discusses the manual and automatic operations, design guidelines, advantages, disadvantages, and applications of the casting. The article describes the number of factors considered when designing and building the molds. It examines the effect of mold design on mold life. The article outlines the primary purposes, procedure, and application of mold coatings. The variables that determine mold temperature and control measures associated with mold temperature are reviewed. The article explains the effect of short-term and long-term variables on the dimensional accuracy of permanent mold castings. It concludes with information on the factors of the surface finish on permanent mold castings.

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, 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.

Sheet molding compound (SMC) is a composite material - consisting of glass-fiber-reinforced polyester in a resin matrix - that’s available in sheet form for the production of compression-molded parts. This article discusses the components incorporated into the resin paste, including catalysts, fillers, thickeners, pigments, thermoplastic polymers, flame retardants, and ultraviolet absorbers, and how to optimize them to achieve the desired processing and molding characteristics and the necessary properties in the resulting parts. The article also presents several mixing techniques, including batch, batch/continuous, and continuous mixing, and describes the operations of continuous-belt and beltless machine type SMCs.

No-bake sand molds are based on 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 discusses 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.

This article provides a general introduction on casting processes and design. It discusses the process steps and methods of the main categories of shape casting methods, namely, expendable molds with permanent patterns, expendable molds with expendable patterns, and metal or permanent mold processes. The article lists general guidelines of geometry in casting design. It describes the factors, such as mold complexity and casting solidification, in casting design. The solidification of a casting can involve as many as three separate contractions as a result of cooling: liquid-liquid contraction, solid-solid contraction, and liquid-solid contraction. The article discusses the factors influencing the solidification sequence of simple shapes, such as T-sections, X-sections, and L-sections. It also provides an overview of geometric factors that influence heat transfer and transport phenomena. The article concludes with a description of the structure and properties of a casting.

This article discusses the types of patterns used for a specific application such as loose patterns, match plate patterns, cope and drag patterns, and special patterns. It describes the principles of the patternmaking techniques used to make expendable molds and for metal casting processes such as die casting and permanent mold casting. The article reviews the pattern features and mold production considerations used in pattern design, namely, parting line considerations, addition of gates and risers, core prints, and locating points. It discusses the pattern allowances for ensuring a dimensionally correct final pattern. A wide variety of materials and advanced composite materials used in the manufacture of patterns are discussed. The article reviews the factors influencing the selection of type of patterns for specific castings.

Horizontal centrifugal casting is used to cast parts having an axis of revolution. This article discusses the operations of various horizontal casting machines, such as flanged shaft machine, horizontal roller-type machine, and double-face plate machine. It describes the types of molds, such as expendable molds and permanent molds, used for centrifugal casting. The article also discusses the steps in casting process, namely, pouring, solidification, and babbitting. It provides information on the applications of the horizontal centrifugal casting.

This article focuses on the variety of alloys, furnaces, and associated melting equipment and on the casting methods available for manufacturing magnesium castings. The casting methods include sand casting, permanent mold casting, die casting, thixomolding, and direct chill casting. The article discusses the flux process and fluxless process for the melting and pouring of magnesium alloys. It describes the advantages and disadvantages of green sand molding and tabulates typical compositions and properties of magnesium molding sands. The article provides information on the machining characteristics of magnesium and the applications of magnesium alloys.

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 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.

Proper sectioning of the surface to be examined is a very important step in preparing steel specimens. The first step in preventing damage to the metallurgical structure is to minimize the amount of sectioning that is done. This article discusses the various metallographic techniques, namely mounting, grinding, polishing, and etching involved in the microstructural analysis of carbon and alloy steels, case hardening steels, cast iron, ferrous powder metallurgy alloys, wrought and cast stainless steels, tool materials, steel castings, iron-chromium-nickel heat-resistant casting alloys and different product forms of steels.

This article describes the metallographic technique for nonferrous metals and special-purpose alloys. These include aluminum alloys, copper and copper alloys, lead and lead alloys, magnesium alloys, nickel and nickel alloys, magnetic alloys, tin and tin alloys, titanium and titanium alloys, refractory metals and alloys, zinc and zinc alloys, and wrought heat-resisting alloys. The preparation of specimens for metallographic technique includes operations such as sectioning, mounting, grinding, polishing, and etching of nonferrous metals and alloys. The article contains tables that list the etchants for macroscopic examination and microscopic examination of nonferrous metals and special-purpose alloys.

This article reviews the pattern materials used in investment casting. It describes patternmaking process, pattern tooling, and pattern and cluster assembly. The article provides information on melting equipment, casting methods, and the inspection and testing of investment casted materials. It presents recommendations that which serve as a useful guide to the design of investment castings. The article tabulates the applications of the process and illustrates the Shellvest system for investment casting of small parts. It explains the manufacturing process of ceramic shell molds and cores. Binders and materials used for ceramic shell molds; slurry and cluster formulation; and pattern removal methods in the manufacturing process are summarized. The article discusses the coating and drying process of clusters and slurries.

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 various molten-metal treatments, namely fluxing, degassing, and molten-metal filtration. It focuses on various molten-metal handling systems for transporting, holding, or delivering molten metal to the mold/die system. These include launders, tundishes, holding furnaces or transport crucibles, molten-metal transfer pumps, teeming ladles, and dosing and pouring furnaces.

Ceramic-forming processes usually start with a powder which is then compacted into a porous shape, achieving maximum particle packing density with a high degree of uniformity. This article compares and contrasts several forming processes, including mechanical consolidation, dry pressing, cold isostatic pressing, slip casting, tape casting, roll compaction, extrusion, and injection molding. It describes the advantages, equipment and tooling, and material requirements of green machining, the machining of ceramics in an unfired state with the intent of producing parts as close to as possible to their final shape. The article also provides useful information on drying methods, shrinkage, and defects as well as the removal of organic processing aids such as dispersants, binders, plasticizers, and lubricants.

This article discusses the classification of the attachment and joining methods in plastics, including mechanical fastening, adhesive bonding, solvent bonding, and welding. It describes the mechanical fastening techniques used to join both similar and dissimilar materials with machine screws or bolts, nuts and washers, molded-in threads, self-threading screws, rivets, spring-steel fasteners, press fits, and snap fits. The article explains solvent bonding used for thermoplastic parts, and tabulates the solvent types used with various plastics. It also describes the surface preparation of plastics, chemical treatment for adhesion, and tabulates the adhesive types for bonding plastics to plastics and plastics to nonplastics. The article briefly describes the welding processes of thermoplastics, including fusion welding (hot-tool, hot gas, extrusion, and focused infrared), friction welding (vibration, spin, and ultrasonic), and electromagnetic welding (resistance, induction, dielectric, and microwave). It concludes with the evaluation of welds using destructive and nondestructive testing.

In the handling of molten aluminum, it is fairly common to use filters as a part of the melting unit and in the gating and/or riser system. This article describes the methods of in-furnace and in-mold filtration, with emphasis on the filtration of molten aluminum. It discusses the factors that influence the formation of inclusions. The article describes the three basic methods of mechanically removing or separating inclusions from molten metal. The methods include sedimentation, flotation, and positive filtration. The article provides a discussion on the types of molten-metal filters, including bonded-particle filters, cartridge filters, and ceramic foam filters. It lists the factors that are important in achieving optimum performance of any in-furnace filtering application. The article concludes with information on filtered metal quality.