Steel still makes up 55% of the overall weight of an average car. The
steel industry maintains that vehicles made of this durable material also are
safer than those fashioned of other materials, a strong selling point. But they
are not necessarily lighter, another a key marketing tool in today's
weight-conscious, fuel-efficient economy.
Aluminum parts account for only 7% of the car's overall weight. However, that proportion has nearly doubled over the last 15 years. The major reason for the surge centers on the material's weight, not its cost advantage.
And, while both materials battle to increase their visibility in the automotive arena, plastics and composite makers invite the car makers to experience what they say their materials can do more effectively than their metal counterparts--consolidate components, provide greater flexibility in molding complex components, and enable engineers to get designs to market quicker. As a result, plastics' success stories continue to grow in both interior and exterior applications, particularly in under-the-hood and structural components.
Steel fights back . Steel doesn't plan to take a back seat to its competitors, however. It invited automakers to form a partnership eight years ago to tackle a wide variety of issues, such as making steel light, but still strong enough to resist dents. Such measures have had an impact on the automakers.
"Steel has changed more in the last five years than in the last 25 years," says Russ Stroud, a Chrysler purchasing executive. "You can get more strength with lighter kinds of steel. That's how steel mills are countering their competition."
The Auto/Steel Partnership consists of a consortium of sheet steel suppliers, Ford, General Motors, and Chrysler. Some of this effort showed up in the design of the 1994 Ford Windstar. The front-wheel-drive minivan contains three times more high-strength-steel parts than Ford's previous-generation, rear-wheel-drive Aerostar. In fact, about 60% of the Windstar's 165 body-structure (body-in-white) components are made of high-strength-steel stampings.
Ford achieved weight savings using several types of the high-strength material. For the three biggest stampings--the two front-door and sliding side-door outer panels--Ford chose electrogalvanized, bake-hardenable (BH) steel for its dent resistance and good formability characteristics. According to Truman W. Owens, an advanced technology process engineer at Ford, his company explored the use of plastic panels for the door, but chose zinc-coated, high-strength steel "because it is lighter than plastic and provides significant cost savings."
Ford also used BH steel on several unexposed structural body parts. Some examples: door reinforcements, body-side hinge reinforcements, D-pillar reinforcements, and roof headers.
Overall, Owens estimates that Ford saved between 5 and 10% in weight by combining high-strength steel with existing technologies throughout the Windstar's body-in-white. This resulted in fuel economy gains for the minivan.
But the story doesn't end here. The consortium has begun work on designing the lightest possible steel-bodied passenger car to help automakers reduce weight even more. For this project, 31 steel producers from Europe, the Far East, Australia, and North America are participating in the research. Porsche Engineering Services, Inc., a U.S. affiliate of the German automaker Porsche AG, will direct the UltraLight Steel