Centrifugal Castings of Metals and Alloys

Centrifugal casting is the process of applying centrifugal force to liquid metal (using a spinning mold), whereupon it solidifies into a dense, sound casting. As metal solidifies in a stationary casting, it undergoes a reduction in volume known as "shrinkage." Shrinkage occurs when the metal on the outside wall of the casting solidifies and "draws" the inside metal toward it until solidification is complete. This "Drawing of metal" leaves cavities which reduce the mechanical properties of the casting.

By applying centrifugal force to the metal as it solidifies, shrinkage can be minimized. As the metal solidifies on the outside wall of the casting, the centrifugal force feeds the inside metal, producing a uniform directional solidification.

The centrifugal casting process involves four necessary operations. These operations include rotation of mold at a predetermined speed, pouring the molten metal, establishment of a proper in-mold solidification rate, and extraction of the casting from the mold.

The purpose of this experiment was to study the effect of rotation speed on casting wall thickness during centrifugal casting. This was observed by pouring four aluminum alloy castings using a centrifugal casting machine constructed at the university.