Full-mold casting technique is quite similar to investment casting, but here polystyrene foam is used as the pattern. The foam pattern is laced with a refractory material. The pattern is put in an encasing of one-piece sand mold, during the pouring of the metal. The foam vaporizes and its place is taken by the metal.
- Complex shaped castings: Possible without any draft or flash.
- Minimum wall thicknesses: 2.5 mm
- Tolerances: Can be held to 3% on dimensions.
- Surface finish: From 2.5µm to 25µm (0.1µin to 1.0 µin) rms.
- Size limits: From 400 g (1 lb) to several tons.
- Draft allowance: Required.