Deformation and Solidification Methods

Method Mold Material Castable Metals Advantages Disadvantages Typical Parts Cast 

Lost-foam sand casting Sand (expendable but recyclable) pattern is consumed Ferrous and nonferrous As above plus no need for parting line better surface finish than conventional sand casting increased dimensional accuracy Increased cost, added process steps As above 

Investment Ceramic (solid or Any, including Intricate shapes and fine Cost, cycle time to build Intricate parts, 

Die casting Reusable metal mold Copper or low-melting-point alloys Good dimensional tolerances, thinnest cast sections possible, quick cycle time High die cost makes it impractical for low volume, limited alloys, need draft/parting lines, size/weight limit Small intricate parts, housings, valves, heat sinks, toys 

Hot tears form when casting sections are constrained by the mold from contracting as they cool near the end of solidification. Hot tears are caused by a number of factors, but poor casting design is the primary cause. Castings should be designed so that solidifying sections are not subject to tensile stresses before they are fully solidified. 

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Zabaras N, Ruan Y (1990) Moving and deforming finite-element simulation of two-dimensional Stefan problems. Commun Appl Numer Meth 6 495-506, Ruan Y, Liu JC, Ricmond O (1993) A deforming finite element method for analysis of alloy solidification problems. Finite Elem Anal Des 12 49-63... 

The moving or deforming FEM method has been demonstrated successfully for modeling the solidification of pure materials by Lynch and O Neill [79],and Zabaras and Ruan [80, 81]. In this method, time dependent finite element interpolation functions are introduced and finite element nodes move with time to adapt to the motion of the solid/liquid interface. Because the interface is continuously traced. 

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