Expanded Polystyrene Process

• In this process, a mold of sand packed around a polystyrene foam pattern is used. This pattern will vaporize when the molten metal is poured into the mould.

• The refractory compound will provide a smoother surface on the pattern and to improve its high temperature resistance.

• Moulding sands usually include bonding agents.

• This process is also called as Lost-Foam process (or) Lost Pattern Process (or) Evaporative-Foam Process.

• The foam pattern includes risers, sprue, gating system, internal core.

• Parting lines and draft considerations are reduced.