The versatility of EPS foam does not stop where the application calls for the unique properties of iron, steel, aluminum or other metal alloys. EPS foam can actually be used to form precision, highly complex metal shapes by the “lost foam” casting technique. Lost foam, like other investment casting methods, begins with the fabrication of the desired cast part first in EPS foam. The EPS foam part is secured in a casting flask. The molten material is injected into the flask, vaporizing the foam and resulting in an exact cast metal reproduction of the EPS foam pattern mold.
The ease and versatility of creating any EPS shape imaginable translates into the ability of the foundry to cast metal parts with the same ease. The lost foam casting technique has been utilized by the automotive, aerospace and manufacturing industries to create precision steel, alloy and composite parts within exact tolerances.
In lost foam casting, the part to be fabricated is first molded or shaped in EPS foam to create a pattern or form. That form is then coated with a refractory coating, placed into a casting flask and embedded into casting sand. The refractory coating imparts a highly finished surface to the cast part and allows the vaporized foam to escape eliminating the need for venting. The molten material is introduced into the flask. As the EPS foam is vaporized by the molten material the cast part takes the shape of the “lost foam” producing an exact cast product free of flash, parting lines or seams associated with common molding processes.
The lost foam technique is often cheaper than other casting methods in that a foam pattern can be fabricated much more easily than a die or mold and foam is cheaper than wax used in common investment casting. Lost foam casting has the additional benefit of producing an excellent surface finish further reducing production costs. Additionally, the mold used to fabricate the EPS foam casting mold is not subjected to the extreme conditions of direct molding and will therefore produce a greater number of identical foam mold patterns to assure consistent quality of cast parts reducing re-tooling costs. The workability of EPS foam invites the casting of custom single unit parts. The fabricator simply shapes the desired part in easy to work EPS foam rather than enduring the time and expense of creating a die mold or machining a part from billet or stock material.
EPS foam, through the lost foam casting technique, delivers another cost-effective and efficient solution to a manufacturing challenge.