DEARBORN, April 22, 2009 – Over the next decade, Ford Motor Company is planning vehicle weight reductions ranging from 250 to 750 pounds that will help it meet stringent fuel economy targets without compromising vehicle safety or durability.  One of the ways Ford has reduced mass in its latest offerings is through the use of light-weight materials such as aluminum and magnesium, and the light-weighting of heavier materials through the use of ultra high strength boron steel.

Light-weight and down-gauged material applications help enable the use of smaller, more fuel-efficient powertrains – such as Ford’s new EcoBoost V-6, which provides the power of a normally-aspirated V-8 with V-6 fuel economy.  Ford introduces EcoBoost on the Lincoln MKS flagship this year, followed by the Ford Flex and other vehicles.

The MKS and Flex are just two of the many Ford products that get some of their core strength from the use of down-gauged aluminum-coated boron steel – one of the strongest weld-able materials – in the body structure.

The use of high-strength steel has helped Ford earn more U.S. government 5-star safety rated vehicles than any other brand and more “Top Safety Picks” from the Insurance Institute for Highway Safety than any other automaker. 

The company’s newest addition, the 2010 Lincoln MKT seven-passenger crossover, is taking Ford’s light-weighting strategy to a whole new level of sophistication and innovation.  The MKT is the first mainstream North American vehicle to feature a liftgate constructed from a combination of magnesium and aluminum, which are more than 40 percent lighter than standard steel. 

“The MKT’s liftgate is the result of a great partnership between our scientific research team, product design team and the supplier.  Together, they overcame significant technical challenges,” said Randy Frank, closures chief engineer, Ford Product Development.  “The use of magnesium and aluminum in the MKT marks a new direction for liftgates and closures in general.”

According to a recent study commissioned by the U.S.-based Aluminum Association, use of the alloy by North American automakers is at an all-time high, averaging 8.6 percent of vehicle curb weight, and projected to reach 11 percent by 2020.  Additional data shows that magnesium production is expected to jump by more than 50 percent from 2008 to 2010, with the auto industry accounting for a third of total global usage.

Ford’s body structure technical experts, whose research will be presented at SAE International’s 2009 World Congress this week, say one of the keys to maximizing fuel economy through the use of advanced materials is the extensive use of computer-aided engineering (CAE) to select the appropriate material and minimize its thickness without sacrificing durability and crashworthiness.

CAE modeling proved essential to the challenging design and development of the MKT liftgate – the largest in the company and possibly the largest thin-walled magnesium closure panel in the industry.  The die casting process enabled the MKT team to fine-tune the part’s shape in a way that wouldn’t have been feasible in a stamped sheet metal part.

Although magnesium raw material cost is a more expensive material than steel, the team determined that an all-steel MKT liftgate would have been too heavy for available power-lift systems to open, and more complicated and expensive to manufacture than one made of magnesium and aluminum. 

“Because it is cast we were able to do variable thicknesses,” said Cindy Wetzel, Ford design and release engineer of liftgates. “We did extensive CAE analysis to see how the magnesium would functionally perform in impact event and made structural improvements such ribbing for added strength.” 

In addition, the use of magnesium and aluminum afforded more design flexibility than steel, enabling the MKT’s swept-forward bustle-back styling without sacrificing interior rear-seat headroom.  Its materials also allowed for an smooth transition from the liftgate to the bumper, which is uncommon in production vehicles.

Aluminum and magnesium vehicle closures were first seen in low volume European luxury cars a few years ago.  The Ford team drew upon first-hand experience developing magnesium doors for the 2004 Aston Martin DB9 and Vantage, and aluminum doors for the 2004 Jaguar XJ and XK.  Ford is looking at future applications for both metals.

The team decided to use magnesium for the liftgate’s inner panel and aluminum for the outer panel.  The choice of the aluminum outer enabled the assembly to be engineered for maximum weight saving, while enhancing the corrosion protection of the inner panel.  In fact, due to the mixture of light metals and steel, the MKT team took great care to assess all liftgate sub systems for corrosion protection.  

Every item of hardware and contact point on the liftgate had to be designed and analyzed for corrosion protection.  Extensive full vehicle and component level testing also were required to prove out its durability.

“Every item of hardware and every contact point on the liftgate had to be designed and analyzed for corrosion protection,” said Patrick Blanchard, materials technical specialist, Ford Research and Advanced Engineering.  “Furthermore, we conducted extensive studies involving component level testing and full vehicle testing to prove out its durability.”

Material experts, body and powertrain engineers expect vehicle weight reduction to account for up to 50 percent of future fuel economy improvements, according to the study commissioned by the Aluminum Association.  The study participants also said that replacing heavier materials with light-weight materials is nearly as important as hybrid technology for automakers to meet the expected increase in the corporate average fuel economy (CAFE) by 2020.

Weight reduction alone isn’t enough to significantly improve fuel economy.  By itself, a 10 percent reduction in weight results in approximately a 3 percent improvement in fuel efficiency.  However, if the powertrain is re-matched, the fuel economy improvement increases to roughly 7 percent.  Weight reduction combined with powertrain re-matching not only improves fuel economy, but maintains overall performance (as compared to a heavier vehicle with a larger engine).

By using magnesium and aluminum instead of steel on the MKT liftgate, the vehicle lost 22 pounds. That, along with other weight saving measures gives the MKT segment-leading fuel economy and its customers a choice of two powerful yet practical V-6 engines.

A 3.7-liter, 24-valve variation of the award-winning Duratec engine family is standard. Delivering an expected 268 horsepower at 6,500 RPM and 267 ft.-lb. of torque at 4,250 RPM, this engine has been tuned to provide brisk acceleration and smooth power delivery. 

For even more performance driving feel, Lincoln MKT also offers a 3.5-liter twin-turbocharged EcoBoost V-6. This engine provides the power of a normally-aspirated V-8 with V-6 fuel economy. This advanced engine delivers a class-leading estimated 355 horsepower at 5,700 RPM, while generating 350 ft.-lb. of torque at 3,500 RPM.