Chill Casting

a method for the production of shaped castings in metal permanent (or chill) molds. In contrast to other casting methods using metal molds (pressure-die casting, centrifugal casting, and so on), in chill casting the mold is filled with molten alloy and the alloy hardens without any outside influence on it other than gravity.

The main operations and processes in chill casting are cleaning of the die to remove the old lining, heating to 200°-300°C, coating the working cavity with a new layer of lining, installation of cores, assembly of the mold, pouring of the metal, cooling, and removal of the finished casting. The process of crystallization of the melt is accelerated during chill casting, which promotes the formation of castings with a dense, finegrained structure and, therefore, good airtightness and superior physiocochemical properties. However, iron castings require subsequent annealing because of the formation of carbides on the surface. Multiple use causes warping of the mold and an increase in the dimensions of the castings at right angles to the plane of the parting line.

Chill casting is used to produce castings from iron, steel, aluminum, magnesium, and other alloys. It is particularly effective in the production of castings for aluminum and magnesium alloys, which have relatively low melting points, making possible the use of a single mold up to 10,000 times (with installation of metal cores). Up to 45 percent of all castings from these alloys are produced by chill casting. In chill casting, the range of cooling rates of alloys and of formation of various structures is broadened. Steel has a relatively high melting point. In the production of steel castings, the durability of permanent molds decreases sharply, and most surfaces are formed by the cores; therefore, the chill casting method is used for steel casting to a lesser extent than for the casting of nonferrous metals.