The production of aluminum alloy wheels mainly uses two techniques of casting and forging.
Casting
Low pressure casting is a relatively basic method for producing aluminum wheels and is also economical. Low-pressure casting involves casting molten metal into a mold and hardening it. Counter-pressure casting is a relatively advanced casting method. It uses a strong vacuum to suck the metal into the mold, which is conducive to maintaining a constant temperature and eliminating impurities. There is no pore in the casting and the density is uniform and the strength is high. The aluminum wheel hub produced by the high pressure die casting (HCM) process is almost the same as the forged one. The RX/RY (15-20 inch) series aluminum wheel of the German factory BBS is cast by HCM method.
Forging
Forging is a more advanced method of manufacturing aluminum wheels, pressing an aluminum ingot under heat to a wheel hub at a pressure of 62.3 MN. The strength of this aluminum hub is three times that of a typical aluminum hub, and the former is 20% lighter than the latter. Some wheels with beautiful shapes and relatively complicated structures are often impossible to forge once. Roll forging (also called die forging) is a type of forging that forges a blank of a hub into a roll. Roll-forged hubs can reduce thickness while maintaining sufficient strength. The aluminum alloy wheel hub manufactured by this process has a uniform density, a smooth surface, a thin wall, a light weight, and can withstand a large pressure. However, since this product requires relatively sophisticated production equipment and the yield is only 50%-60%, the manufacturing cost is slightly higher and the price is naturally not low.