NSK Reveals Lightweight Wheel Bearing Hub Unit

NSK Reveals Lightweight Wheel Bearing Hub Unit NSK Ltd. (Japan; TSE1: 6471) announced it has developed a new automotive wheel bearing hub assembly unit which is significantly lighter, yet stronger than current designs. The entire hub unit weighs just 2.3 kilograms (5 pounds), where comparable units on the market today weigh at least a 2.8 kg (6.2 lb.). Each pair of hub units on a vehicle will reduce its unsprung weight by more than a kilogram (2.2 lb.). The hub and spindle components of NSK's new design are produced by cold forging; NSK says theirs are the first commercially available wheel bearing hub units to employ cold forgings. In cold forging, a slug of material is forced into a forming die under extremely high pressure. Hot forging involves first melting the material, then pouring it into a die. NSK claims machining the hub and spindle components from cold forgings allows more strength to be maintained in those components than hot forging techniques. Consequently, wheel bearings produced using cold forgings can be smaller without sacrificing strength. While a kilogram of weight savings may not seem particularly substantial, the target market for these new units is smaller cars, typically powered by 1.5 to 1.8 litre engines. Lighter hub units not only improve fuel economy, but also take weight out of traditionally nose-heavy front-drive vehicles, producing more favorable weight distribution. NSK's lightweight wheel bearings also hit another critical target for automakers, which is reducing unsprung weight. Unsprung weight is the weight of the wheels, tires, brakes and suspension. Reducing it is a key goal for automakers because doing so enhances not only fuel economy but also braking, handling, acceleration and ride comfort. Employing lighter hub assemblies is a weight-saving option often preferable to other methods already in use -- thinner brake discs, use of expensive lightweight calipers, ceramics, and exotic alloys for other suspension components. NSK said it is targeting first-year (model year 2009) sales of the new units in the range of ¥1 billion (USD $8.6 million).