Centrifugal Casting

To sand-cast a pipe you need a core suspended precisely inside the mould to form the bore — a core that must be made, positioned, held against the buoyancy of molten metal, and then broken out afterwards. Centrifugal casting removes it entirely. Spin the mould fast about its axis, pour metal in, and the metal is flung against the wall and held there while it freezes, forming a bore whose diameter is set purely by how much metal you poured. There is a second benefit that turns out to matter more: the same spinning drives light impurities and gas inward toward the bore, so the dense, sound metal ends up on the outside where the strength is needed. Dimitri Sensaud de Lavaud made it an industrial process for pipe around 1918.