Although not a common feature on vehicles originating in the North American market, European automakers have been installing underbody closure systems on their passenger vehicles for some time. Starting with small plates intended to protect the engine and gear box, these shields have evolved into complete under-floor closure systems offering a number of benefits.rnFirst, they reduce the vehicle's aerodynamic drag, which helps improve fuel economy - vital in a market segment where fuel prices average 0.98 - 1.56 € / liter ($5-8 USD / gal).rnSecond, they function much like the protective vinyl coating sprayed on the underside of most North American vehicles to reduce stone impingement, salt spray, and other damage to the undercarriage. Unlike the spray coatings, however, the shields also protect the undercarriage on bad roads and for off-road usage.rnThird, they reduce noise - both inside the cockpit for occupants, as well as curb noise as vehicles pass through congested cities with narrow streets.rnAs underbody closure systems have proliferated, different materials and process development programs have been commercialized. Each participating OEM has sought to tailor these closure systems to achieve specific combinations of cost, performance, and mass for the various vehicle segments in which they compete. Although no single material / process option currently meets all OEM needs in all segments, 3 technologies - all thermoplastic - have emerged in Europe to dominate underbody closure systems. This paper discusses current material / process options and the kinds of application criteria where each are best suited.
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