Search Results for lost foam casting

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.

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.

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.

Depending on the size and application, castings manufactured with the expendable mold process and with expendable patterns increase the tolerance from 1.5 to 3.5 times that of the permanent pattern methods. This article reviews the two major expendable pattern methods, such as lost foam and investment casting. It discusses the Replicast casting process that involves patternmaking with polystyrene and a ceramic shell mold. The article contains a table that summarizes the differences in the steps of casting a part between the permanent pattern and expendable pattern methods.

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.

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 provides a general introduction on casting processes and design techniques. 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 the general guidelines of geometry in casting design. It describes the three separate contractions that are a result of cooling: liquid-liquid contraction, solid-solid contraction, and liquid-solid contraction. Factors influencing the solidification sequence of simple shapes, such as T-sections, X-sections, and L-sections, are discussed. The article also presents an overview of geometric factors that influence heat transfer and transport phenomena. It concludes with a description of the structure and properties of castings.

Casting is one of the most economical and efficient methods for producing metal parts. In terms of scale, it is well suited for everything from low-volume, prototype production runs to filling global orders for millions of parts. Casting also affords great flexibility in terms of design, readily accommodating a wide range of shapes, dimensional requirements, and configuration complexities. This article traces the history of metal casting from its beginnings to the current state, creating a timeline marked by discoveries, advancements, and influential events. It also lists some of the major markets where castings are used.