Some Little Things About Materials

When you’re looking for weight reductions, it is the little things that matter, too.

Let’s face it: Generally when people think about “materials” in the context of automotive, they think of things like, say, the recently introduced high-strength aluminum alloys from Novelis (novelis.com), the Advanz 7000 series. According to Novelis, these alloys are two- to three-times stronger than any aluminum used in high-volume automotive applications, and they lend themselves to applications including bumper systems, door intrusion rings and crash-ring components. (Novelis knows more than a little something about what aluminum materials are being used in high-volume auto applications, as it is a supplier to the Ford F-150, the Range Rover and the Jaguar XE.)

But there are plenty of materials-related developments that aren’t as widely noted, yet are essential, particularly as there is the on-going requirement to reduce mass in vehicles, something that is going to have to happen gram-by-gram.

For example, Freudenberg-NOK Sealing Technologies (fnst.com) has developed a polytetrafluoroethylene (PTFE) radial shaft seal for engines that is smaller—requiring a minimum installation height 50% less than that required for conventional radial shaft seals—and 40% lighter than traditional seals.

Given that the BlueSeal is rather, well, small, this begs the question about how much lighter it is. According to Freudenberg-NOK, a conventional shaft seal weighs some 50 grams. The new seal weighs just 29 grams.

Another notable aspect of the seal, which can withstand a wide variety of oils and fluids found in various regions around the world, is that it has a low-friction lip design that insures smaller dissipation loss and reduces the temperature in the contact area between the seal and shaft.

Another small but important materials-based development has been introduced by ContiTech Vibration Control (contitech.de), a thermoplastic polyurethane gaiter, a component for premium luxury cars with air suspensions. The component is attached inside the wheel arch to protect the air suspension against stone impact.

Heretofore, the gaiter has been produced from thermoplastic polymers, but by switching to primarily thermoplastic polyurethane, the component is more flexible and has greater rebound strength, thereby providing greater resistance to abrasion from things like rocks kicking up on the inside of the wheel well.

Another ContiTech materials-related development is a torque clutch that is said to be more than 50% lighter than previous variants. The clutch is for cars with electric power-assisted steering, connecting to the powertrain system.

This is a multi-material assembly that makes use of a carbon-fiber-reinforced polyamide. While this material has had applications for such things as transmission crossbeams and torque rod supports, according to ContiTech, this is a first for torque clutches.

Another plastic material used in the assembly is a thermoplastic polyure-thane. Overall, the torque clutch is wear-resistant, which is important in its application.

And then there is a top mount—the component that links the shock absorber to the chassis—developed by BASF (basf.com) that weighs about 25% less than the traditional die cast top mount.

The company brings to bear two of its materials, its Cellasto micro-cellular polyurethane elastomer and its Ultramid A3WG10 CR 50% glass-fiber reinforced polyamide. The former is used in place of a rubber insert; the latter is used for the housing. BASF has developed a manufacturing process through which the materials are permanently joined.

This component has an effect on the overall NVH of a vehicle. So the polyurethane elastomer has to exhibit static and dynamic behavior, and the fiber-reinforced polyamide needs to handle dynamic loads.