Once the casting process is completed, the aluminum wheel is allowed to cool. Next, workers inspect each part for anomalies. Then, depending on the intended wheel design, a light de-flashing operation is conducted to remove any leftover slag. In some cases, the wheel may be sent to be shot-peened to improve surface hardness and strength. Shot-peening is a cold-working process in which small spherical media (aka shot) bombard the surface of a part.