Expendable-Pattern Casting

Patterns in this process are melted out prior to casting modern lost-wax process for ceramic molds, or they burn up and evaporate during pouring, as does polystyrene foam in the lost-foam process for sand molds. So, the mold can be in one piece, eliminating parting lines.

Draft is decreased to that required for releasing the pattern from its mold. Preheating of ceramic molds allows casting of parts with thin walls and small cores, as in super alloy turbine blades with internal cooling passages. By assembling several pattern pieces, shape complexity can reach the highest level of any manufacturing process, as exemplified by bronze castings of statues.