Sand casting is the most versatile of all processes used to cast aluminum. Pouring molten aluminum alloy into a sand mold produces a casting. This process is well suited for producing small quantities of identical castings, complex castings with intricate cores, large castings and structural castings.
A mold cavity is formed into bonded sand by using a pattern to create an impression, which is a duplicate of the actual part. The sand is contained in a flask. If required, a sand core is then placed in the cavity to create an intricate detail in the casting. A core print is the region added to a pattern that is used to locate and support the core inside the mold. Sprues are formed to introduce the molten metal to the mold, gates direct the metal to the impression and risers contain excess molten metal to compensate for shrinkage as the casting solidifies. After cooling, the casting and sand are removed from the flask. The sand core is removed, leaving the intricate detail in the casting. Cleaning operations include cutting, grinding, and abrasive blasting. Secondary operations such as machining, anodizing, plating and balancing can then be performed. If required, sand castings can be tested, including nondestructive testing.
The sand casting process offers the following advantages:
- The required tooling is relatively inexpensive, and can be produced with relatively short lead times.
- Configuration and process changes, if required, can be made quickly and inexpensively.
- Small quantities of parts, including single casts, are cost-effective.