Cast: a process where a liquid material (aluminum) is poured into a mold that contains a hollow cavity of the desired shape, and then allowed to harden. casting is the easiest and most cost-effective way of making a wheel, and it uses the least material also. like billet, the grain structure that results from casting aluminum is not as uniform nor as closely aligned as forged, and therefore not as strong.
Forged: shaping metal by using localized compressive forces. forging is normally considered the strongest process of manufacturing aluminum parts because the pressure of the process aligns the grains and maximizes its strength. this pressure usually comes in the form of hammering or compressing the aluminum. its density is increased-resulting in superior strength.
Billet: the term "billet" applies to the original chunk of aluminum from which a wheel emerges. it starts as molten aluminum that has a mixture of gases that are forced through it to purify it. The aluminum is then poured into molds, creating the billet. to make the solid aluminum billet into a wheel, it is machined by a cNc (computer Numerically controlled) mill that follows pre-programmed instructions to remove the unwanted material using high-speed cutting bits.