The foam pattern used in lost foam casting is typically made by injecting expanded polystyrene (EPS) beads into a mold that is shaped like the desired final metal part. The EPS beads are heated and expand to fill the entire mold cavity, creating a three-dimensional foam pattern. Once the foam pattern is formed, it is removed from the mold and assembled with other foam patterns to create a cluster. The cluster is then coated with a refractory material to create a shell around the foam patterns. During the metal casting process, the molten metal is poured into the shell, vaporizing the foam patterns and filling the void with liquid metal, resulting in the desired metal part.
