Alcoa Helps Vehicle Manufacturers Leverage Wheel Forging Investment

November 16, 2009
Aluminum billet gets ready to be forged.
As OEMs revitalize the appeal of their cars and prompt new car sales, they look to refresh or differentiate their product offerings with little or no additional tooling investment. Adding new wheel programs to a model range can often change the look and feel of the car and help improve the desirability of that car. Alcoa’s flexible forge manufacturing process can now offer car makers the opportunity to launch these new wheels, not only in a rapid time scale, but also at low cost.
 
Alcoa has refined a process that through variations in design, machining and finishing, generates an infinite variety of styles from a single forged tool. Wheels using this process are amongst the strongest, lightest wheels available but with the structural integrity to meet the toughest fatigue requirements.
 
Additionally, Alcoa has advanced wheel finishing, including its patented Dura-Bright® technology surface treatment, allowing a wheel to be further differentiated not only by design and structure but also appearance and performance.
 
The base forging blanks are produced from billets of 6061-T6 aluminium, using the same metallurgy as the wheels Alcoa produces for the Boeing 747. An optimised forged wheel can be half the weight of a typical cast alloy wheel of the same diameter due to the superior material properties of these wheels.
 
"We can vary the wheel style and finish options widely, within a given forging envelope, without changing the base forging, resulting in many different styles with a single forged tool investment," says David Yates, Commercial Manager for Alcoa Auto Wheels Europe. "We are now using this principal widely for OEM customers in Europe and the USA. Chrysler, for example, adopted this for the SRT family; wheels for the various models look quite distinctive yet share the same tooling. GM launched a range of buzz model wheels. They were all launched quickly from a single tool investment and have been very successful."
 
As well as styling freedom, forged wheels provide a fast-to-market, cost-effective weight reduction; in particular, the lightweight rim sections reduce the rotational inertia of the wheel which improves the fuel efficiency of the car and reduces CO2 emissions. Lower wheel mass also means less work for the suspension; tires remain in better contact with the road surface as lighter wheel assemblies are easier to control when hitting bumps; particularly important when cornering. This translates into improved grip, traction and braking, better vehicle control and a smoother ride.
 
Manufacturing also benefits, becoming leaner. Apart from commonality of tooling, Alcoa’s approach results in reduced inventory and offers shorter lead times since the final machining is able to draw from a common stock of forged blanks. The machining process is cost-effective, requiring only 3-axis machines for most applications, though 5-axis capability is used for exotic designs such as the Lamborghini SV.
 
"Prestige brands such as Ferrari and Lamborghini already use our products, as do higher volume customers such as Audi and Chrysler," concludes Yates. "The volume of inquiries is increasing rapidly because stylists like the design freedom; engineers like the light weight and accountants like the control of tooling costs."