As can be surmised, feeding of the molten metal in centrifugal casting is achieved through centrifugal force produced with a revolving mold. Thus, in effect, it is basically a pressure casting method. Best known and simplest of the centrifugal techniques is generally referred to as true centrifugal casting. In this method, the mold is spun about its own axis and the inside of the casting is formed by centrifugal force acting on the metal. No core is required and the interior cavity becomes a true cylinder, regardless of the exterior shape, whose diameter is determined by the volume of metal poured. A centrifugal casting machine is shown in Figure 1 (Ref. 1).