Casting molds are made of machined sections of steel. When all the pieces come together, a cavity is formed into which the molten aluminum is poured. This is what is known as a counter-pressure casting mold. It’s pressurized with molten aluminum, but because gravity begins the process, the mold is positioned vertically. The technician is spraying a releasing agent on the upper part of the casting mold to keep the hot aluminum wheel casting from sticking to the mold.