metalcasting

Metalcasting is a manufacturing process in which molten metal is poured into a mold and allowed to solidify into a shaped part. It enables complex geometries, hollow sections, and varying wall thicknesses that are difficult to achieve with subtractive methods.

The principal casting methods are sand casting, investment casting, die casting, permanent mold casting, and shell molding. Sand casting uses a sand-based mold and is versatile for large parts but may yield coarser surface finishes. Investment casting coats a wax pattern in a ceramic shell to produce high dimensional accuracy. Die casting injects molten metal under pressure into steel dies for high-volume production and tight tolerances. Permanent mold casting uses reusable metal molds for consistent parts, while shell molding forms thin ceramic shells for precise parts.

Materials cast include ferrous alloys such as gray and ductile iron and steel, and nonferrous alloys such as aluminum, magnesium, zinc, and copper alloys.

Typical steps in a metalcasting operation are pattern or core making, mold making, melting and pouring, solidification, shakeout and cleaning, and finishing and inspection.

Applications span automotive engines and powertrain components, machinery parts, valves and fittings, and art objects. Quality is governed by tolerances, surface finish, and often non-destructive testing; standards come from organizations such as ASTM and ISO.

Advantages include the ability to produce complex, near-net shapes with relatively low tooling costs for varied geometries. Limitations include porosity, shrinkage, surface finish variability, and potentially longer lead times for small batches. Environmental and safety considerations cover handling of molten metal, fumes, and waste management, with recycling of scrap metal common in the industry.