Surfaces of cast-iron castings subjected to constant wear, such as car-wheel rims, anvil faces, and vehicle wheel boxes, are chilled to render them hard and tough. The chilling is done by sudden cooling of the molten iron when it is poured into the mould. A part of the mould is formed of a piece of iron, and when the molten metal comes in contact with this, its surface is quickly cooled.

Fig. 126. - Chill for a Mould.

Fig. 126 shows a chill for a car wheel. This forms the cheek of a three-part flask. Chills are made of cast iron or cast steel.