Automobile wheels are largely classified into three categories: steel, alloy, and special (forged). The main substance of an alloy wheel is aluminum alloy (A356.2). This aluminum alloy, which is 30% lighter than steel and has exceptional stiffness, helps contribute to outstanding stability and fuel efficiency. With an increasing trend in lightweight and luxurious auto parts, as well as current gas price increases and the needed replacement of steel wheels, demand on alloy wheels is expected to grow continuously.