06/12/2014
What is Forged Wheel, and why is it better than Cast Wheel?
The ultimate in one-piece wheels (mono-block). Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure. This creates a finished product that is very dense, very strong and therefore can be very light. The costs of tooling, development, equipment, etc., make this type of wheel very exclusive and usually demand a high price in the aftermarket.
To make a high quality, strong and light forged wheel, it takes several steps from forging the aluminum steel bar to billet, then go through the under-cutting the inner part of the rim, following with CNC machining, polishing and color coating.
Forged wheels are superior to cast wheels. They start out as aluminum billet, typically 6-7 inch diameter bar stock. These are then cut into the right length, heated, and pressed into shape under about 6-12,000 tons of pressure. The forging process imparts a lot of energy into the metal and changes the internal grain structure of the aluminum (metals have a crystalline structure) and this change in the grain structure is what gives a forging additional strength in comparison to the original billet rod. A forged aluminum wheel has a higher specific strength, as well as higher toughness in comparison to a casting. This allows for a wheel that is lighter, stiffer and less susceptible to cracking under impact and with better fatigue properties than a casting.
Castings, conversely, are made from molten aluminum that is poured into a mold. After it is cast and cooled, there is usually some final machining and finishing work to get it to fit the right application and to have a nice finish. Some cast wheels are heat-treated as well. This is how most wheels are made and a high quality pressure cast product, that is well engineered, can result in a nice quality wheel. The major disadvantage is that they tend to be heavier than forged wheels due to their relatively low material strength properties.
