Thursday, 31 March 2005 17:00

Will aluminum and other materials leave some shops behind?

Some shop owners say the use of aluminum in vehicles today is similar to the shifts in the industry caused by the rise of the unibody structure in the 1980s. 

Their reasoning: Unibody vehicles required very different repair equipment and procedures than did conventional frame vehicles; aluminum repair requires different tools and techniques from traditional steel vehicles. Not all shops jumped to get the equipment and training needed for unibody repair, and those that did had an economic advantage for a time; shops mastering aluminum repair today say they too have a lead in the marketplace, even getting work referred to them by other shops.

And while unibody construction was used in a small minority of vehicle models at first, its use became widespread rather quickly; similar predictions are being made for the growing use of aluminum.

But aluminum is not the only change in vehicle materials and construction that collision repairers will face in the coming years. The steel industry is determined not to lose the automotive market, so new steels will also pose new challenges for shops.

Automakers and industry analysts offer this glimpse into the future of automotive manufacturing and materials to help those collision repairers who are determined not to fall by the wayside as some did during the "unibody revolution."

Aluminum coming of age

The changes in vehicle materials are based in large part on the need to reduce weight. With U.S. drivers reluctant to downsize their vehicles, and a growing array of high-tech and safety add-ons, automakers are being challenged to meet existing and future fuel economy standards.

Not surprisingly, the aluminum industry has been lobbying hard - and largely successfully - to get automakers to view its product as the lighter-weight alternative to steel for both structural and non-structural parts.

A 2002 study found that the average aluminum content for passenger cars and light trucks was 274 pounds, a 23-pound increase since 1999. While wheels and engine blocks account for some of that increase, the number of aluminum closure panels also rose from 2.2 million parts in 1999 to 3.8 million parts in 2002.

That rate of growth has continued as automakers develop new techniques for using aluminum. GM, for example, uses "quick plastic forming" to create panels for its Malibu Maxx liftgate. A heated aluminum sheet is subjected to high-pressure air that makes it conform to the shape of a hot tool. This enables the entire outer panel for the liftgate to be made as one piece instead of two (one steel and one plastic) that would later need to be joined together.

For collision repairers, the rising use of aluminum poses a number of challenges. Aluminum can be gas metal arc (or MIG) welded, although some automakers, notably Porsche, call for the use of gas tungsten art (or TIG) welding. Aluminum is also a much better conductor of heat and electricity, so higher amperage and voltage settings are required when welding. Aluminum also expands and contracts about twice as much as steel, so distortion and weld cracks can be an issue.

The aluminum oxide that naturally forms on bare aluminum to protect it from corrosion must be removed using a wire brush prior to welding. Once this is done, the aluminum should not be touched with bare hands to avoid contaminating the surface.

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Aluminum requires dedicated tools

Perhaps one of the key aspects of working with aluminum in the shop is that the wire brush and other hand tools used on it should be used only on aluminum. Tools and abrasives used for steel may contaminate an aluminum surface. Tools should be marked "aluminum only." Some vehicle manufacturers, including Audi and Jaguar, even call for a dedicated aluminum repair area in the shop.

The right equipment and procedures are important in measuring and straightening aluminum vehicles, and like the unibody of the 1990s, this may pose a challenge to some shops. Magnetic target attachments used for measuring won't attach to an aluminum frame. Some of these vehicles also require special anchoring clamps. Some automakers use rivets rather than resistance spot welds on the pinchweld, so special clamps, with spaces for the rivets between the clamping surfaces, are needed.

It's no wonder I-CAR has developed several new courses focused solely on aluminum, as well as a hands-on aluminum welding test.

Big Steel fights back

But the steel industry is by no means conceding the automotive market to the aluminum producers. The "ultralight steel auto body" (ULSAB) is the result of a 5- year-old consortium of 35 steelmakers from 18 countries. The project's goal was to design a steel car body for a typical 5- passenger sedan that reduces total weight without raising costs or sacrificing safety or performance. The result was a structure with 25 to 36 percent less weight, superior rigidity and vibration measurements, and no increase in production costs over a conventional steel-bodied vehicle.

That made the steel industry happy, but what will it mean for collision repairers?

"Many of the technologies used in ULSAB are now in current model vehicles, which means that automakers have developed extensive repair procedures," said Marcel Van Schaik, one of those involved in ULSAB through the American Iron and Steel Institute.

ULSAB includes five primary manufacturing materials and concepts that collision repairers need to understand.

High strength steels: While about 20 to 30 percent of current vehicle bodies are made from high-strength steels, these materials account for about 91 percent of the ULSAB. Like all steel, high-strength steel gets even harder when it crumples. It will not be as easy to straighten parts or remove dents in the material after it undergoes the additional hardening effects of a crash.

Hydroformed tubing: A section on each side of the ULSAB vehicle is made of "hydroformed tubing." The one-piece tubing starts at the top corners of the windshield, runs above the doors and back down to the rear well area. Van Schaik said working with hydroformed tubing parts is not new to collision repairers. General Motors, for example, has used the tubing in the lower rails of the Corvette, the side roof rail in the Cadillac Seville, the chassis and engine cradles in many GM vehicles, and the frame of the Sierra/Silverado truck lines.

Sandwich materials: Some of the non-structural portions of the car body, such as the spare tire tub and dash panel insert, are made from a steel sandwich material. Two very thin skins of steel combined with a plastic core create a 1-millimeter thick material weighing 50 percent less than a comparable all-steel piece.

Tailor-welded blanks: The ULSAB body side, including the rear fender, sill and roof structure, is all one part made from a tailor-welded blank that includes three grades of steel and five different thicknesses. By consolidating what has traditionally been multiple parts into one unit, designers also eliminate the weight of the weld flanges needed to join the parts together. Fewer reinforcements and parts also reduce the number of places corrosion is likely to take place.

While there has been limited use of tailor-welded blanks in some vehicles for nearly a decade, almost 50 percent of ULSAB's structure incorporates tailor- welded blanks, one of the most aggressive uses of tailor blanks in the industry today. Though there are as yet no specific sectioning recommendations, the lack of inner reinforcements leaves open more possibilities than conventional designs.

Laser welding: One repair area that is not as familiar in North America as it is in Europe is how to handle parts joined by laser welding. ULSAB employs significantly more laser welding than conventional body structures; it is used, for example, to join the roof panel to side roof rails and to join front rails.

"Volvo may have been the first company to use a laser-welded roof," Van Schaik said. "European collision shops remove the damaged roof and replace it using a combination of adhesive bonding and MIG welding."

Van Schaik said that although ultralight steel will mean some changes for collision repairers, the end result is a vehicle made of a material shops are very familiar with: steel.

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New steels pose challenges

Another new steel collision repairers are encountering in vehicles is boron steel. Often called the "ultra-high" high-strength steel, the boron used on some Volvo models is, for example, about four times stronger than average high-strength steels. In addition to Volvo, which is using boron steel for some bumper reinforcements, door guard beams, inner B-pillars and inner rear body panels, Porsche and Mercedes-Benz are among the automakers putting boron into use on current model vehicles.

The process used to make boron so strong takes away some of the steel's workability properties. It can be welded just like any other steel, but it can only be cut or drilled with special tools. And because of the extremely high heat used when it is being formed, boron steel cannot be straightened. Trying to straighten it without heat will generally lead to cracking; heating it will destroy the strength of the part.

When sectioning procedures and cutlines are available for some of these boron parts, the process involves cutting the steel with a cutoff wheel or plasma-arc torch, not a reciprocating saw. But it's trying to drill the spot welds out of boron steel that really poses a challenge for collision repairers. Even very durable drill bits dull very quickly when drilling boron. I-CAR recommends using a titanium drill bit at a slow speed (490 rotations per minute compared with the average 1,800 rotations per minute used to remove most spot welds).

Because boron steel cannot be galvanized, proper corrosion protection is especially important when working with it. Weld-through primer should be applied to all bare steel mating flanges, and primer should be removed only from the direct area to be welded. Epoxy primer should be applied to the entire part(s) after welding.

Not being left behind

The arrival of the unibody vehicle is the time many people point to as the dawning of the modern collision repair industry. It led to the development of I-CAR and formalized on-going technician training. It sparked progressive shops to invest in the tools and training to get an advantage over their competitors in the market. And many see it as contributing to the push for more professional business practices among shop owners.

Some see aluminum and the other new materials and techniques used in vehicle manufacturing as signaling the arrival of another key step in the development of the collision repair industry. Like the collision repairers of 25 years ago, today's shop owners must decide whether to do what is necessary to stay in the game, or watch the industry pass them by.

John Yoswick is a freelance writer based in Portland, Oregon, who has been writing about the automotive industry since 1988.

 

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