fuel economy standards, so have steel wheels been replaced. “Even considering any kind of
decorative hub caps, you will see steel wheels on less expensive cars,” Crick said. “T e disadvantage is they are heavier, and they aff ect handling char- acteristics and fuel economy.” Not all aluminum wheels are
cast. A smaller percentage is forged. Around 70% of aluminum’s 73.3% to- tal market share is estimated to be cast. Typically, the wheels are made in the low pressure permanent mold process, but other methods also are used. Enkei uses tilt pour permanent mold casting; some others use diecasting. According to Schorn, casting a wheel makes more economic sense than forging, whatever the material. “Forged wheels are typically more
expensive than cast because the process is more expensive,” he said. “Hypotheti- cally, If a cast wheel costs $65, a forged wheel is going to cost $100. You will see forged wheels on designer cars or cars that have heavy load ratings—mostly trucks because of the mechanical prop- erties you get with the forging process.” To wed the mechanical properties
of forging with the design freedom of casting, Enkei has developed a propri- etary hybrid process. “T at is why we developed fl ow
forming technology,” Schorn said. “As the diameters [of wheels] have grown, the side walls have shrunk, so that transmits more road forces and the rim has got to be stronger. Flow forming will give you near forged properties in the rim area, which happens to be the weak point.” Light-weighting and economic
considerations aside, the most impor- tant factor in the great shift to cast aluminum from forged steel wheels was aesthetics, according to Lilley. “It was customer demand—looks,”
he said. “People got tired of hubcaps. T ey are a pain in the neck, and they don’t look very good. So when the aluminum prices started coming down, people said ‘hey I like these.’ You can fi nd some styled steel wheels, but they don’t look like aluminum.” Does this mean that aluminum (and aluminum castings) will reign over the wheel market indefi nitely? Lilley isn’t sure.
Nov/Dec 2011 | METAL CASTING DESIGN & PURCHASING | 35
About 70% of the automotive wheels produced today are aluminum castings.
“Forging is on its way [out] from a cost standpoint, although there has been forging capacity built in Asia,” he said. “I’m not going to say it can’t come back.” Casting capacity in Asia and other
low-cost countries also still presents a signifi cant threat to the future of the North American wheel market.
“We fi nd plenty of things to do
every day to continue to make our product,” Borick said. “And we are going to be conservative in how we spend our capital [and approach the] need to build additional capacity. But if we can’t get a return, we need to look at other opportunities.”
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