Casting is a simple, inexpensive, and versatile way of forming aluminum; so it is not surprising that it was also the first method used.
Such items as the baby rattle for the French emperor's son, the cap atop the Washington Monument, and the tea kettle were all produced by aluminum casting.
The Production Process
The three most important methods are die casting, permanent mold
casting, and sand casting.
Die casting, in which molten metal is forced into a steel die, or
mold, under pressure is normally used for high-volume production.
Accurate parts, requiring a minimum of machinery, can be produced via
Permanent mold casting involves molds and cores of steel or other
metal. Molten aluminum is generally poured into the mold, although a
vacuum is sometimes applied.
Permanent mold castings can be made stronger than either die or sand
castings. Semi-permanent mold casting, which uses expendable cores of
sand or other material, is used when permanent cores would be impossible
to remove from the finished part.
The most versatile method is sand casting. Virtually any pattern can be pressed into a fine sand mixture to form a mold into which the aluminum is poured. This is a slow process, but it is usually more economical for small quantities, intricate designs, or when a very large casting is needed.
Cast aluminum is also widely used in other forms of transportation,
including aircraft and marine engines and other structures.
Parts of small appliances, hand tools, lawnmowers, and other machinery use thousands of different aluminum castings. But the cast product most often seen by consumers is cookware - the aluminum product that was the first made available for everyday use.