innovations CASTING
Improving Structural Effi ciency in Suspension Components
K
nuckles are the most important component in defi ning and control- ling the position of the wheel (axle or spindle)
and steering (a.k.a. “kingpin”) axes of a vehicle’s front suspension. Vehicle steering knuckles support and posi- tion the wheel bearing and spindle, while providing the connection to the control arms and/or struts. Traditionally, these compo-
nents were made from ductile iron or stamped steel, with more high-end parts made from forged steel. Beginning in the late 1990s, aluminum began to dominate, with high-end knuckles made from
Compass produced a unique steering knuckle for Tesla’s Model S sedan using semi-permanent mold VRC/PRC casting technology to produce a fully hollow part.
forged aluminum and a growing percentage of more low-end knuck- les made from cast aluminum. Compass Automotive Group,
Fruitport, Mich., in conjunction with Tesla Motors, Palo Alto, Calif., devel- oped a fully hollow steering knuckle for Tesla’s Model S sedan using semi-permanent mold, vacuum/pres- sure riserless casting (VRC/PRC) technology. T e Model S component is the world’s fi rst series production application for a fully hollow cast aluminum front steering knuckle. Hollow cast-aluminum knuckles represent an advancement in technology and structural effi ciency for this family of parts. “Previous incarnations of
hollow aluminum castings for a steering knuckle have only resulted in hollow gooseneck areas, as op- posed to the entire knuckle,” said Rick Borns, director of engineering and business development, Compass Automotive Group. Compass produced the part using
a sand core that extends from the up- per ball joint attachment all the way
48 | METAL CASTING DESIGN & PURCHASING | Jan/Feb 2013
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