Expandable-Mold Casting Processes with Expendable Patterns
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 Replicast casting process involving 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 the expendable pattern methods.
This article discusses the sequence of operations for producing a foam pattern for casting. It provides information on expandable polystyrene (EPS), the most preferred material for manufacturing lost foam patterns. The article describes the major functions of pattern molding and assembly for the lost foam process. The purposes and application of various lost foam coatings are also provided. The article describes the investment of the foam pattern in sand system. It discusses the advantages of lost foam casting and concludes with information on formation and reductions of folds in lost foam casting.
Expandable-Mold Casting Processes with Expendable Patterns, Casting, Vol 15, ASM Handbook, Edited By Srinath Viswanathan, Diran Apelian, Raymond J. Donahue, Babu DasGupta, Michael Gywn, John L. Jorstad, Raymond W. Monroe, Mahi Sahoo, Thomas E. Prucha, Daniel Twarog, ASM International, 2008
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