CuproBraze® 63 EXECUTRIVepoErt CuproBraze Proves Versatile in the Design of Heat Exchangers Key Advances Include “One-Shot” Brazing and New Tube Designs uproBraze has long been considered a versatile and flexible materials system. One-Shot Brazing Typically, heat exchanger cores of There have been many successes in the different sizes and designs are pro- refinement of brazing processes for the cessed on the same production line, manufacture of CuproBraze products. The unlike other processes such as brazed process has proved quite flexible for the Caluminum. For the latter, because of the dif- manufacture of many shapes and sizes ficulty of establishing the correct processing CuproBraze products. Brazing as part parameters, high volume production lines science and part art has been covered in dedicated to identical products are the rule. previous issues of the ICA CuproBraze For the CuproBraze process, flexible Executive Report [1] as well as the technical manufacturing is the rule. The underly- literature [2]. ing reason why the CuproBraze process is The ultimate reference on CuproBraze suitable for flexible manufacturing is that brazing is the “CuproBraze Brazing it allows for more latitude or leeway in Handbook,” which includes 37 figures and temperature cycling than other processes. tables in 15 chapters and 110 pages [3]. It In other words, the temperature cycle that covers such topics as materials and proper- melts the brazing material can be varied ties; application of brazing filler materials; significantly without damaging the bulk fabrication and assembly of components; metals. This simple fact has important brazing of cores in a furnace; key factors consequences for the production environ- for good results; and troubleshooting. ment as well as design. Members of the CuproBraze Alliance are CuproBraze technology is proving becoming adept at developing brazing pro- versatile in design. As the number of cesses. As proof, consider the development CuproBraze manufacturers increases, appli- of the “one-shot” brazing process. One of cation engineering and design engineering the biggest challenges is to braze differ- are flourishing. Products are being designed ent types of joints simultaneously, during for ease of manufacture. In addition, the one pass through the furnace. One-shot superior strength of the joints formed by brazing is possible with a process such as the CuproBraze process is enabling original CuproBraze, because the CuproBraze pro- designs for heat exchangers. cess provides enough process latitude to This Executive Report briefly describes braze different geometries simultaneously. the “one-shot brazing” of CuproBraze One-shot brazing requires familiarity charge air coolers and new “multiport” with the properties of the filler materials CuproBraze tube designs. These two and adherence to geometric tolerances in advances in design are presented as exam- the assembly of the components. One- ples of the renaissance in heat exchanger shot radiators and charge air coolers are design that is taking place as the virtues “designed for manufacturing.” Once the of CuproBraze technology become better exact tolerances and brazing application appreciated by heat exchanger manufactur- methods are determined and the furnace ers and OEMs. temperature cycle established, the process The International Copper can be implemented in a production need for pressure resistance, which is Association, Ltd. (ICA) environment with high yields. important in A/C applications. Round One-shot brazing tends to improve cross-sections of multiport tubes are The International Copper Association, Ltd. (ICA) is the overall manufacturing quality because it especially resistant to pressure. Different leading organization for promoting the use of copper requires tighter tolerances of dimensions. cross-sectional geometries (e.g., variations worldwide. The Association’s 38 member companies In one-shot brazing processes, furnace of port diameter, wall thickness and dis- represent about 80 percent of the world’s refined copper temperatures are gradually increased and tance between ports) are possible using output. ICA’s mission is to promote the use of copper parts are heated evenly. Strains due to dif- multiport tubes and are simply a matter of by communicating the unique attributes that make this ferential temperatures are less than those tooling. sustainable element an essential contributor to the formation of life, to advances in science and technology, present in welding processes. The greatly Prototype designs have now been and to a higher standard of living worldwide. improved dimensional stability makes revealed for multiport tube assemblies it easier to install heat exchangers into fabricated from two matching CuproBraze For information about the CuproBraze process or ICA’s vehicles because of the accurate alignment brass strips. Strips are formed with alter- CuproBraze consulting services, please contact the of oppositely-facing fixing points. nating troughs and flat sections and rolled International Copper Association at: The labor saving advantages of one- locally together. Even though no brazing [email protected]. shot brazing are significant. One-shot paste is applied between the two strips, For European inquiries contact: [email protected]. brazing eliminates the need for skilled the joints are strong enough to withstand welders at the post-brazing production the normal core assembly procedure. stage. One of the first companies to use During the ordinary brazing furnace cycle References the one-shot brazing method in volume the strip joints obtain their final strength production is Finnradiator, a member of by diffusion. Brazing paste is applied in 1. See ICA CuproBraze Executive Report Numbers 19, 23, 34 and 39 for more about the CuproBraze Alliance. It currently uses a usual manner for the tube-to-fin joints, brazing. See Numbers 41, 42 and 46 for more one-shot brazing for the manufacture of tube-to-header joints and so on. about testing of brazed joints. Available in the charge-air coolers for several models of In this manner, tough, reliable, mul- Literature section of www.cuprobraze.com. Valtra tractors. The company reports a tiport tube components can be readily 2. An updated list of technical papers about the savings in total labor time of about 25 fabricated for use in the production of CuproBraze brazing process is available in the percent when the one-shot method is fac- novel heat exchanger products. Literature section of www.cuprobraze.com. tored in at the design stage [4]. 3. “CuproBraze Brazing Handbook,” Ninth Several other companies have developed Design Renaissance Edition (Updated July 2009) can be down- one-shot brazing methods for medium loaded free from the Literature section of volume production runs. For example, CuproBraze is proving itself more www.cuprobraze.com with registration. Vintage Air brazes heating units with a flexible and versatile than could be envi- 4. Luvata Automotive Newsletter Number 51, one-shot process [5]. Many other compa- sioned when the process was first devel- “Partnering with Finnradiator results in suc- oped more than a decade ago. Although cessful ‘one shot’ brazing.” Available at www. nies have tested one-shot brazing of proto- types in laboratory-scale production runs. the groundwork was laid when the basic luvata.com/Automotive-Newsletter. technology was developed, a renaissance 5. See ICA CuproBraze Executive Report Number of heat exchanger design is taking shape 54, “Vintage Air Commences Production Multiple-Port Tube Design today. This renaissance is driven by the of Brazed Copper-Brass Components for Durable, Compact Designs” for more about Small diameter or flat tubes are used availability of a completely new materials one-shot brazing by Vintage Air. Available in in heat exchanger designs to increase the system and the ingenuity of CuproBraze the Literature section of www.cuprobraze.com. contact between the fluid and the inner brazing experts and design engineers. walls of the tube. The surface-to-volume It is envisioned that multiport tubes ratio affects the efficiency of the heat will be components of heat exchanger exchanger. Thin-walled tubes are also cores that will be brazed simultaneously desirable both in terms of materials sav- with other fittings. The shape of this new ings and heat conductivity. generation of CuproBraze heat exchang- Yet, the assembly of many individual ers is a topic of great excitement in the small tubes can be problematic for heat-exchanger design community. The assembly. Brass cannot be extruded into designs, cooling fluids and end-uses of the multiport tubes so an alternative method next generations of heat exchangers are for the fabrication of multiport tubes has still a work in progress but one thing is been under research. for certain: A renaissance in heat exchang- An important motivation for the devel- er design is underway and CuproBraze opment of multiport tubes has been the technology is at the center of it. ■ International Copper Association, Ltd. 260 Madison Avenue, 16th Floor, New York, NY 10016-2401 Tel: 212.251.7240, Fax: 212.251.7245.