Centrifugal Casting Machine force alone
The casting of a plain pipe or tube is accomplished by rotation of a mold about its own axis—the bore shape being produced by centrifugal casting machine force alone, and the wall thickness determined by the volume of metal intro‐duced. This practice is widely referred to as "true centrifugal casting." 
• In the case of a component of varying internal diameter or irregu‐lar wall thickness, a central core may be used to form the internal contours, feeder heads then being introduced to compensate for solidification shrinkage. • A further step away from the original concept is the spacing of separate shaped castings about a central downsprue which forms the axis of rotation. These variations are referred 
to respectively as "semicentrifugal casting and centrtfuging or pressure casting." In both cases, since the castings are shaped entirely by the mold and cores, centrifugal force is used primarily as a source of pressure for feedin g.