Recent Developments in Semi-Continuous Casting of Aluminum Alloy Billets and Slabs

In spite of the development of several continuous rod and sheet casting processes, the D.C. (direct-chill) short-mold casting process, used on a vertical semi-continuous basis, still accounts for the major part of aluminum alloy production. The process is used primarily to cast round extrusion billets, rectangular rolling slabs, square wirebars and forging stock and special shapes, such as T-ingot. In line with larger output requirements, there is now a trend to larger semi-continuous casting machines of heavy-duty design, offering a greater number of multiple cast strands, longer cast lengths and larger cast cross-sections. Demand for castings to be made at highest production rate, with uniform quality and at lowest cost necessitates the maximum possible use of casting system automation, particularly in the areas of controlling metal temperature, metal flow, cooling water temperature, cooling water flow, casting speed and cast length.