Weight Watchers

Scrap recyclers watch closely as automakers choose between steel, aluminum and other materials in their quest to build lightweight vehicles.

Auto manufacturers are designing with a basic thought in mind: eliminate unnecessary weight. As a result, aluminum and plasticoften are replacing steel in cars and lighttruck components. The steel industry has fought to retain its place by introducing new light-weight, high-strength steels.

Scrap recyclers are faced with a couple of questions as they observe this trend toward lighter materials. Is what’s good for meeting Corporate Average Fuel Economy (CAFE) standards, good for the overall recyclability of the cars and light trucks produced? And, will the vehicles retain enough metal to make them economically desirable as scrap commodities?

THE CAFE MENU

Congress passed CAFE standards, which require auto manufacturers to meet a miles per gallon target, hoping they would help to reduce America’s dependence on foreign oil by producing more fuel-efficient vehicles. The CAFE standards took effect in 1978 with the introduction of an 18-miles-per-gallon requirement for passenger cars. The current CAFE requirements, which were established in 1985, are 20.7 miles per gallon for light trucks, SUVs and minivans and 27.5 miles per gallon for domestic and import passenger cars.

In early November of 2001, Representative Bernard Sanders, an Independent from Vermont, introduced the Comprehensive Energy Conservation Act for the 21st Century to the House of Representatives. The bill calls for increasing the CAFE standard to 34 miles per gallon for passenger cars and 27.5 miles per gallon for light trucks manufactured between the 2004 and 2011 model years.

The Aluminum Association’s Dick Klimisch, vice president of the Auto and Light Trucks Division, Detroit, says the federal government is moving rapidly to increase the fuel economy of automobiles, particularly light trucks, and aluminum, at roughly 60 percent steel’s density, is often a viable option for automakers.

APPETIZING ALUMINUM

Klimisch says that aluminum currently accounts for about 9 percent of vehicle weight. Aluminum use in SUVs and light trucks is growing at a faster rate than in passenger cars because the auto industry is under pressure to improve their fuel economy and performance relative to passenger cars, he says.

“The beauty of it is not only does it improve fuel economy, but it improves the performance, increases the payload,” Klimisch says. “It’s a wonderful performance advantage for the light truck fleet. I think this could be the advantage that the domestic automakers need to maintain their market share in trucks.” 

Aluminum is used in extrusions, bumper beams and steering systems, Klimisch says. “There’s quite a bit of surface aluminum being used in fenders, hoods and lift gates for SUVs,” he adds.

One auto industry source says that the traditional cast iron engine block is moving to die cast aluminum. While he says it is “extremely likely” that aluminum will displace cast iron in engine components, he is not as optimistic about sheet applications. “Until we see more of a narrowing of the price differential between aluminum sheet and steel, it’s going to be very difficult for aluminum to make aggressive ground on the sheet side of the vehicle,” the source says.

Terry Cullum, director of Global Design for the Environment at General Motors, Detroit, says, “I think it has been shown that you can basically build a fairly aluminum-intensive vehicle. There are issues with the manufacturing process – the assembly processes of aluminum – in terms of joining things together that might slow its rise. Obviously, the cost is an issue as well.”

Cullum says that there are several materials helping to reduce the weight of automobiles, including plastics. “But I think most predominant now are the nonferrous metals – aluminum, magnesium and in some cases, even titanium, are finding their way onto new vehicles.”

Aluminum is increasing in the power train and chassis areas, Cullum says, “and that’s where you’re going to find magnesium and titanium as well.”

However, the steel industry is slimming down to remain competitive.

STEEL: STILL THE MAIN COURSE

“The steel makers have done a very good job of staying responsive to a market that is increasing demands in terms of product quality and cost,” Cullum says. “I think the lightweight steels are a good example of their ability to innovate to really meet our changing demands.”

Bill Heenan, president of the Steel Recycling Institute, Pittsburgh, says that 50 percent of the steels used in cars today were not available 10 years ago. “A new family of what we call high-strength steels is being introduced. We call them high-strength steels because they allow the automaker to take mass out, but to increase the strength that goes into the vehicle,” he says.

Heenan says the new high-strength steels, in combination with laser welding, allow the automakers to put strength in the places where it is most necessary. “You don’t need high-strength steels everywhere in the cage,” he says.

Edward Opbroek is program director of Ultra Light Steel Auto Body – Advanced Vehicle Concepts (ULSAB-AVC), a project designed to demonstrate how to optimize steel’s qualities to produce lightweight auto structures that meet a variety of mass, performance, safety and cost targets. The program is managed and funded by an international consortium of 33 steel producers. Porsche Engineering Services Inc. of Troy, Mich., provided the engineering work and much of the technical support. Opbroek says that the program has developed ultra light auto closures and suspensions in addition to auto bodies, and the ULSAB-AVC will combine all these developments.

Opbroek remarks that the focus of the family of projects is to “take steel, an established material, and examine the concepts for using the advanced high-strength steels that have been developed in recent years using holistic design” that incorporates new manufacturing techniques and optimal designs. Tailored blanks account for nearly 40 percent of the body structure of the AVC vehicles, with hydroformed parts totaling more than 20 percent, according to the ULSAB-AVC.

“You can’t just substitute a different material.” Opbroek says. “You have to address all three issues and, always, address the cost issue.”

High-strength steels make up 100 percent of the USALB-AVC design, with more than 80 percent being advanced high-strength steels such as dual phase (DP) and TRIP (transformation induced plasticity), Opbroek says.

Opbroek describes DP steel as having a lower strength to begin with, which makes it easy to form into a complicated part. The DP steel undergoes strain hardening during the manufacturing process, resulting in stronger steel capable of absorbing more energy in a crash, he says. “It’s sort of the best of both worlds. It makes it easier to manufacture initially, and it makes a much stronger [vehicle].”

Opbroek says that DP steels allow the auto manufacturers to build a lighter vehicle structure by using thinner, stronger material.

“I think in general that’s where I expect the most growth to be in the future because it’s such a good combination. It gets the high strength in the end, it’s easy to form in the beginning and it’s very economical,” Opbroek adds.

He also points to the recyclability of steel as an advantage. “The infrastructure is in place. These advanced high-strength steels, innovations in steel materials, don’t change anything about the recycling infrastructure,” Opbroek says. These innovations also allow for source reduction during manufacturing, he adds.

Heenan also says the steel industry can offer automakers and consumers materials that result in vehicles that continue to be highly recyclable in addition to being safe, affordable and fuel-efficient.

Some other materials that may be efficient from a fuel economy standpoint—particularly plastics—may not be as readily recyclable.

IS PLASTIC PALATABLE? 

Many automakers now are using plastic in fuel tanks, which have historically been made of steel sheet. Interior engine components that are often cast aluminum or cast iron, such as the intake manifold, are also being made from plastic.

However, Cullum thinks plastic shows its greatest potential for use in exterior applications. “Our company obviously has used plastics in our vehicles for decades for exterior applications.”  Both the Corvette and the Saturn line feature plastic exterior parts. “At this point, I don’t think it’s really overtaking steel the way people thought it might,” he says.

Recyclers have two options for recovering plastic body panels, Cullum says. “The first is to remove the panels before the vehicle is shredded to keep the plastic materials segregated to enhance the recycling process. The second is to allow the vehicle to be shredded and to recover the plastic materials after the shredding process.” Cullum says that the United States Council for Automotive Research is helping to fund research into a process for recovering plastic from the shredder residue similar to that used for recovering nonferrous metals.

Sheldon Jarcaig, vice president of sales for Ferrous Processing and Trading (FPT), Detroit, says, “If our industry witnesses a growth in the use of plastic, I anticipate technology developments to facilitate the recovery of recycled plastics from auto shredder residue.”

Jarcaig adds, “Although it is impossible to forecast the type of plastics that will gain favor, published reports predict that in 2005, over 12 billion pounds of engineered plastics will be used by the world automobile industry in the production of 59 million light passenger vehicles. Approximately 35 percent of auto shredder residue consists of plastics that are sent to landfills and not recycled. Our industry bears the burden of these increased disposal costs.”

Marty Wilhelm, president of Youngstown Iron and Metal, Youngstown, Ohio, says his company has seen steady increases in the fluff content of auto shred. “We also see an increase in nonferrous recovery, but are not sure if this is process improvement, increased substitution or a change in market conditions.”

Jarcaig says, “Obviously, aluminum and steel are better suited for recycling. However, I do believe that there will be ongoing pressure [to improve] auto plastics recycling.”

RATE OF REDUCTION

The automobiles shipped to shredding facilities in the 1980s were manufactured largely in the 1970s and weighed approximately 3,000 pounds, Jarcaig says. “Today, vehicles shipped to shredders average approximately 2,000 pounds. As a result of this trend, our shredding facilities use a lower percentage of automobiles by weight as feedstock.”  He adds that heavy-duty shredders have allowed FPT to process material, such as demolition scrap and light structural steel, previously destined for shearing operations. “The advantage of this feedstock is higher recovery rates than that of scrap automobiles.”

As far as downstream recovery is concerned, Wilhelm says Youngstown Iron and Metal does not sell a clean aluminum grade from auto shredding. Instead, the company sells its shredder residue to another processor who then separates it into specific products and grades. “We concentrate on trying to recover all the metal from our fluff, thereby increasing revenue,” Wilhelm says.

FPT is “definitely” focusing on capturing a clean aluminum grade with eddy current separators and other sorting processes, Jarcaig says.

Both Jarcaig and Wilhelm have noticed that dismantlers are “picking off” some of the vehicles’ high value parts.

“Without question, dismantlers today are recovering a higher percentage of salvageable parts and nonferrous metals prior to scrapping out vehicles to shredding operations,” Jarcaig says. “Catalytic converters, which recently sold for as much as $40 each, and aluminum components such as wheels are definitely being removed more frequently. Due to the recent trend of low scrap prices, dismantlers are simply looking for additional methods to improve their revenue stream.”

Wilhelm also no longer receives catalytic converters from dismantlers. “Aluminum wheels have always been a favorite [source of] ‘found money’ for dismantlers,” he adds.

As to whether auto manufacturers are designing for recycling, Wilhelm says, “Absolutely not. There is almost no interaction between recyclers and auto manufacturers. The domestic recycling and steel industries face potentially huge environmental problems with both air bags and mercury in automobiles.” 

Tracy Mattson, director of environmental compliance for the Institute of Scrap Recycling Industries Inc. (ISRI), Washington, agrees. Although  auto-makers may have made strides in designing with recycling in mind, she says they can make a significant difference in regard to the recyclability of their vehicles.

“We’ve heard anecdotal stories about an SUV dashboard having 11 different plastic components – 11 different kinds of plastic. That’s not ensuring the recyclability of that product,” Mattson says. “When looking at an application, it should not be only a matter of function, it should be a matter of life cycle as well.” Mattson stresses that automakers should consider whether the functionality of a product outweighs the potential recyclability barriers the product may create, adding that automakers should continue to ensure that their products continue to be among the most recycled products in the world.

The author is assistant editor with Recycling Today.