The foamcast® - lost foam casting process can be best characterized as a hybrid of the investment casting process in terms of molding but with an expendable pattern made from high-quality Expanded Polystyrene (EPS) as in lost foam process (instead of the wax pattern used in the lost wax/investment casting process).

The EPS pattern is coated in ceramic slurry and then fired where EPS pattern is fully vaporized in the process to produce a ceramic mold before casting this allows a wide range of alloys to be cast in the ceramic shell - including ultra low carbon stainless steel to nickel based alloys. This prevents carbon pickup from the EPS pattern during solidification.

This is in contrast to the conventional lost foam process where the liquid metal melts and replaces the Polystyrene Foam Pattern, making it unsuitable for the almost all of steel components. The reason being Expanded Polystyrene is 92% by weight carbon and this carbon is absorbed by the casting during pouring.

EPS (Expandable Polystyrene) Pattern Molding Process Video:

Coating Process:
After the  EPS (Expandable Polystyrene) Pattern is dried and assembled after gluing the runners and risers to the EPS Pattern the process for preparing ceramic shells as casting molds begins, wherein
1. The EPS Pattern is dipped into a dip-coating composition of a slurry of a refractory material and a binder in order to form a wet coating on the pattern.
2. A coarse refractory powder is sprinkled onto the coating,
3. The coating is dried, and
4. Steps 1, 2 and 3 are repeated until the mold shell has reached the desired thickness.

Burn-off Process:
The Coating is dried in an oven at 120 oven at 120-140°F(49-60°60°C) for 3 to 5 hours. Post Drying the Pattern is put in a Furnace for Burn-off.

Compaction:
The Ceramic Shell is delivered to the Flask parked on the pouring line by conveyor or by hand. The Cluster is placed into flask and held in position by a fixture or by hand. During the compaction the flask is vibrated at a preset frequency so the the sand is compacted without damaging/breaking the ceramic shell.

Pouring & Extraction:
Metal is poured to fill in the hollow shell. The Casting is allowed to cool in sand for a predetermined period. Sand in the Flask is then dumped on to a conveyor for recycling. Loose sand around the casting cluster helps protect the parts from damage.

Note: Non-proprietary terms that have been used to describe similar processes include:  cavityless casting, evaporative foam casting, foam vaporization casting, lost pattern casting, the castral process, expanded polystyrene molding, EPC, Evaporative Pattern Casting, LFT, Lost Foam Technology, Expendable Pattern Casting, lostfoam, shellfoamcast, etc.