Iscar Metals
Can Copper Make A Comeback?

Will stricter emissions rules permit copper to make a comeback in automotive radiators? The International Copper Association surely thinks so-as does a new manufacturer, which happens to be located in Siberia.

“Shadrinsk” is not a name that comes readily to mind when one thinks about the vehicle industry, but this small Siberian town is now home to the most advanced copper radiator and charge air cooler (CAC)–collectively known as “heat exchangers”—production facility in the world. As such, it may be on the leading edge of a trend back toward copper as the material of choice for heat exchanger components. Soldered copper units once dominated the heat exchanger business, but over the past two decades manufacturers moved en masse to lighter weight aluminum assemblies. The copper industry was slow to respond to the threat, but eventually the International Copper Association (ICA) developed a new manufacturing technology dubbed “CuproBraze” that it claims leapfrogs aluminum techniques. But with aluminum firmly ensconced among the world’s major vehicle makers, making inroads for CuproBraze has been an uphill slog. Now, government regulations promise to make the going a little less tough.

Stricter emissions regulations in the U.S. and European Union slated to kick in as early as 2004 (and cut emissions by nearly half) are forcing makers of large capacity diesel engines for Class 7 and 8 vehicles to improve volumetric efficiency for more complete combustion. This means a significant increase in inlet pressure and temperature (from an average of 190°C today to an estimated 246°C). At these higher temperatures, aluminum loses tensile strength and is weakened by repeated thermal cycling. “Aluminum is failing at the under hood temperatures now required by the U.S. EPA for Class 8 trucks,” says Garry Faulkner, technical manager for the Swedish copper company Outokumpu, which helped install the line in Shadrinsk. The answer to this problem proposed by aluminum heat exchanger makers is to add a pre-cooler unit that will keep the temperatures of the air or liquid at acceptable levels. ICA’s pitch is, “Why bother complicating the system with extra parts and cost when copper and brass heat exchangers can handle the temperatures with ease?” And because copper dissipates heat more quickly, the size of heat exchanger units can be reduced while maintaining the same cooling capacity.

The downside for copper is that it is heavier than aluminum, which makes it a tough sell to automotive engineers bent on reducing vehicle weight. But perhaps the biggest stumbling block in the path of copper adoption is the sheer amount of investment and infrastructure that has been put in place for aluminum. Established manufacturers are loathe to spend the money needed to re-tool for copper—and that is one of the reasons why the world’s largest CuproBraze line is located in Siberia. Emerging markets like Russia and China offer a clean slate for the development of a copper-based infrastructure. They also provide a platform for exports that could help copper get a toehold in world markets. Vladimir Kolotushkin, general director of Russian auto parts maker SHAAZ, which owns and operates the Shadrinsk plant, says “As long as demand is present and our prices are competitive, nothing is barring us from exporting CuproBraze heat exchangers anywhere on the globe. Our goal is to export 50% of our production capacity.” In fact, SHAAZ has already begun export activities by signing a supply deal with Daewoo in Korea.

As the first high volume CuproBraze line a lot is riding on the success of SHAAZ. ICA hopes it will prove to be the concrete example necessary to sway manufacturers toward switching to copper. And though the process has a long way to go to topple aluminum, some momentum already seems to be building. Gert Lundmark, managing director of Outokumpu’s sales arm in Asia says, “Several big projects are in the works in Asia with both OEMs and suppliers. I expect there will be 12 to 15 CuproBraze lines in the region by 2006.”

The present focus is on big diesel engines, since the strongest business case can be made in that segment. But prototypes for cars and even motorcycle heat exchangers have been produced and aggressively promoted directly to OEMs. Eventually, copper supporters want to see their beloved metal where it once was; at the top of the automotive heap.

All That SHAAZ

Shadrinsk Auto Aggregate Plant (SHAAZ) sounds like a name that could have easily originated from a Soviet central planning apparatchik, and in fact, the manufacturing complex dates back to the era of Stalin. But the production line housed in the facility’s non-descript buildings clearly belongs in a 21st century market economy.

laser weldersemi-automated processbelt furnace
Brass tubes that form the structure of the heat exchanger core are made by folding brass strip and sealing it in this laser welder.Heat exchanger cores are assembled from brass tubes and copper fins in this semi-automated process.After assembly the cores are loaded onto a continuous belt furnace which heats them to 600°C to braze the components together.

SHAAZ’s CuproBraze line is an integrated production process that takes in large cassettes of copper and brass strip at one end and turns out finished heat exchangers at the other. At the beginning of the largely automated process, the brass strip is folded into tubes which are sealed with a laser welder and then cut into predetermined lengths. The copper strip is folded into corrugated fins and cut with louvers, or turbulizers, to increase heat-dissipation capacity. (The tube mill can produce 100 m/min of tubing and the fin mill can produce 25 m/min, or enough for 250 to 300 heat exchanger cores per eight hour shift, depending on the size of the units.) The fins and tubes are then sprayed with a lead-free brazing paste (supplied by BrazeTec; Hanau, Germany) using a spray nozzle technology that significantly reduces wasted material. Header plates that encase the tops and bottoms of the brass tubes that form the structure of each heat exchanger are sprayed with a slurry that acts as a bonding agent in the brazing process. The coated components are then assembled in a semi-automated process and made ready for the furnace. (The tube and fin mills and paste and slurry application machines are all supplied by Scholer Spezialmaschinenbau GmbH; Pansdorf, Germany.) The cores are loaded onto a continuous belt brazing furnace (supplied by Seco/Warwick; Meadville, PA) which heats them to over 600°C for three minutes in a nitrogen atmosphere to permanently bond the tubes to the header and the fins to the tubes. Before being released into the open air, each core cycles through a nitrogen atmosphere convection cooling section that reduces part temperature to 150°C, shortening the overall length of the line.

SHAAZ is methodically ramping up its CuproBraze line and expects to be at full capacity of 450,000 units/year by 2005. It is currently focusing on serving Russia’s alphabet soup of domestic makers (KAMAZ, GAZ, URALAZ, UAZ, VAZ…) which make up the bulk of its business. But it’s ISO 9001 certified, making it a credible global supplier, and it has a clear desire to enter the North American market. Which could give a whole new meaning to the phrase, “The Russians are coming.”