Alloy Wheels – The Manufacturing Process
There are basically three processes when it comes to manufacturing alloy wheels which are one-piece in construction: Cast alloy wheels, Forged alloy wheels, and Billet alloy wheels. Each one of these will produce a highest quality alloy wheels; however there are some distinct differences in the strength of the finished product worth noting.
A Cast alloy wheel is a manufacturing process whereby molten aluminum is pored into an alloy wheel mold and once it is cooled, the result is a wheel. There are three types of Cast wheel production: Gravity fed, Low-Pressure fed, and Spun-Rim.
Gravity fed alloy wheel manufacturing is the least expensive method for producing an alloy wheel. The molten aluminum is pored into the alloy wheel mold with the use of the Earth�s gravitational force.
Low-Pressure fed alloy wheel manufacturing costs slightly more to produce but the alloy wheels is much stronger and lighter than the gravity fed constructed alloy wheel. In this process, molten aluminum is forced into the mold at a high rate or it can be vacuum packed into the alloy wheel mold. The process results in a denser wheel giving it superior strength over the gravity fed casting.
Spun-Rim alloy wheel manufacturing has an even greater expense compared to the Low-Pressure fed wheel, but again the construction is much better and much lighter. This process begins the same as the Low-Pressure fed system (molten aluminum forced into an alloy wheel mold), however once the rim of the wheel is formed, it is then spun and super heated. At this point steel rollers are used to apply pressure to the molding in order to squeeze the rim to the final dimensions. This produces an extremely dense and strong rim.
A Forged alloy wheel is a manufacturing process in which intense heat and pressure is used to force a chunk of aluminum (often called a slug or stock) into the alloy wheel shape desired. This process will create an alloy wheel which is up to 300% stronger than a Cast alloy wheel and is lighter as well.
A Billet alloy wheel is a manufacturing process hereby a chunk of aluminum is machined into the alloy wheel design. This involves a very expensive machine called CNC (Computer Numeric Control) which reads specific instructions and then drives the machine tool to complete the task.
There are also two-piece alloy wheel and three-piece alloy wheel constructions which generally involve a combination of the cast and forged processes. By dividing the alloy wheel into two or three pieces, a much greater intricacy can be achieved with the overall design. Often the rim is the forged piece and the wheel center is the cast piece, this is due to needing more strength in the rim of an alloy wheel versus the center.
Once the alloy wheels are produced, any excess aluminum is cut-off, the alloy wheels are then put through trimming and sanding to smooth all edges and surfaces, and finally the alloy wheels are either painted or plastic coated.
The reason for the various alloy wheel manufacturing processes is due to what the customer is requiring or wanting the alloy wheels to do or achieve. A race vehicle will benefit greatly from forged wheels or billet wheels because of the weight savings, whereas someone who wants a beautiful wheel to dress up their vehicle would not be concerned with greater strength and weight reduction. The choice is up to the individual, their needs and tastes. Fortunately there are a myriad of options available in alloy wheels in order to suit each person’s needs.