The International Copper Association has applied new technologies to the manufacture of advanced copper radiators.
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Throughout automotive history, copper has been the metal of choice for car and truck radiators, although aluminum has assumed a significant market share in original equipment radiators over the past 20 years. In the 1970s the auto industry started the shift from copper/brass to aluminum for new car and truck radiators because aluminum's lighter mass and perceived stable market price gave the metal a comparative advantage. Today copper holds 39% of the total radiator market worldwide, and 89% of the aftermarket.
According to the International Copper Association (ICA), density is the only distinct advantage of aluminum, although an important one. But for radiators, the density and weight issues are far more complicated, as are many issues concerning copper and aluminum. Aluminum has better conductivity than brass, but radiator tube strength is equally, if not more, important. Brass is considerably stronger than aluminum. This overall strength allows for thinner walled tubes that compensate for the difference in conductivity. Taking advantage of these characteristics-increased thermal conductivity, strength, and corrosion resistance-manufacturers can use thinner material throughout and thereby design a copper/brass radiator having a lower total mass than one made from aluminum, but with the same or better heat rejection capacity.
With the application of several new technologies to the manufacture of advanced copper radiators, the copper industry may soon regain shares of the market lost to aluminum since the 1970s. Developed by the ICA, the CuproBraze process uses a controlled-atmosphere or batch furnace and provides flexibility during manufacturing. The technology includes anneal-resistant copper fins and brass tubes, plus a new process for brazing these components into a monolithic, extremely strong radiator unit. The manufacturing process is simple, flexible, and eliminates steps such as pre-washing and flux applications necessary with the aluminum process. The process also eliminates soldering, so the entire radiator core can be recycled into new radiators.
The key advantage of the process is the wide margin that exists between the brazing temperature and melting point of copper/brass. In the CuproBraze process, brazing occurs at 600°C (1112°F), 300°C (572°F) below the melting temperature of brass. ICA states that in the commonly used Nocolok process, a much slimmer margin of 40°C (104°F) exists between brazing and melting temperatures. Universal Auto Radiator Manufacturing Co. in Pittsburgh, PA, is currently producing between 30 and 50 CuproBraze radiators per day for more than 90 automobile models.
