Sand Casting



The sand casting process involves a pattern (made out of wood, plastic, or metal) that is made in the shape of the desired part. Sand casting can produce simple designs (made in a single piece) or more complex ones (made in two parts, called split patterns). The split pattern casting has a top and bottom section, referred to as a cope (top) and a drag (bottom). The patterns are packed in sand with a binder, which hardens the sand into a semi-permanent shape. When the sand mold is cured, the pattern is removed and a hallow space in the sand is left in the shape of the desired part.
When the metal cools, the sand mold is removed and the metal part is ready for secondary operations, such as machining & plating. Sand casting is the least expensive of all of the casting processes. It is used to make larger parts than other casting methods. Metals that are commonly used in the sand casting process include iron (most popular), steel, bronze, brass, and aluminum alloy.

ADVANTAGES

• Least expensive casting process
• Castings can be up to several tons
• Can cast intricate shapes
• Can be used with most pourable metals and alloys

DISADVANTAGES

• Can only cast basic parts shape
• Castings require secondary machining
• Rough surface finish