Lost Foam Casting

Lost Foam Casting is used particularly for automotive applications. It is molding technique that produces patterns by blowing polystyrene beads into aluminum mold cavities. Injecting steam into the tooling cavity expands the beads. The beads will flatten against the tool surface and stick to one another. After cooling, the patter is ejected from the tool.  

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Lost Foam Casting is used particularly for automotive applications. It is a molding technique that produces patterns by blowing polystyrene beads into aluminum mold cavities. Injecting steam into the tooling cavity expands the beads. The beads will flatten against the tool surface and stick to one another. After cooling, the patter is ejected from the tool.

The multi component patterns with gating systems are assembled with contact adhesive. The assembly is coated, usually by dipping, in a permeable coating, and then air or oven dried at 140° F or less. The coating prevents sand collapse during pouring. The coated pattern-gating assembly is set in a flask, and the unbonded sand is added to the flask. In order to compact the sand, the flask will first need to be vibrated during filling. When molten metal is poured into the mold, the pattern vaporizes, allowing the metal to fill the mold cavity.

It is not necessary to have risers in the aluminum castings, and core parting line shifts have been eliminated. Some advantages to a lost foam process are cleaning room costs are reduced, tooling for foam patterns does not erode, and manual power requirements are lessened.