„Large format contacts“
Conductive resistance brazing
Using optimized Bihler process technology, it is now possible to apply 10 x 10-mm contacts to copper carrier strips of up to five millimeters in thickness. They are attached using conductive resistance brazing with precisely controlled energy input to achieve components with very high dimensional stability – on strips or on finished individual parts.
For decades, welding, and in particular resistance welding, has being one of Bihler’s core competences. One important application in this field is contact welding, i.e. the application of small precious-metal roundwire, lamellar or profiled-strip contacts to strip material. In this area, Bihler has implemented thousands of welding applications that guarantee outstanding process reliability, productivity and weld quality. In the field of contact welding, Bihler has recently witnessed an increase in demand for so-called load break switches. The contacts of these components ensure that the electricity supply is disconnected quickly and reliably should the need arise and they are installed, for example, in e-vehicles and as load switches in domestic engineering applications. Because these components are exposed to particularly high amperages, they need to be sufficiently large and the contacts are attached to the corresponding carrier strips by means of resistance brazing. In the past, however, process-related considerations meant that the thickness of the carrier strip, which is usually made from copper, was restricted to a maximum of three millimeters.
The B 20K welding controller is a key component in the new large-format resistance brazing process. It makes it possible to manufacture up to 30 welded parts per minute.
Conductive brazing
Bihler has now opened up a completely new dimension in the resistance brazing of contacts: “We have optimized our existing process in a way that allows us to apply 10 x 10 mm contacts to copper carrier strips of a thickness of up to five millimeters,” explains Martin Ott, Head of Welding Technology at Bihler. “This represents a huge leap forwards in resistance brazing technology and it is opening up a whole new world of production potential.” The really clever thing here is that while most contacts of this sort are applied using inductive brazing, Bihler uses conductive brazing. This is not only faster but also offers benefits in terms of thermal behavior: “Conductive brazing only partially heats the component and only introduces a small amount of heat into the area of the contact,” explains Ott. “This has a very positive effect on the dimensional stability of the component.” The vital element in this new large-format resistance brazing process is the B 20K welding controller, whose performance capabilities have once again been enhanced for this task, in particular at the level of the inverter and transformer.
30 parts per minute
In practical operation, the components are fed to the welding point and the multilayer section that is to be brazed is drawn in by the welding system and separated. The two components are positioned under the electrodes, which then close and perform the resistance brazing operation. This normally takes one second. The system then opens again and the components are stepped forward in the cycle or are removed from the welding position. In general, it is possible to manufacture up to 30 welded parts per minute in this way. The entire process can be implemented in a stand-alone unit or can be integrated in neighboring Bihler systems.
On strip material or on individual parts
Another highlight is the fact that these particularly large contacts can be brazed to strip material or to finished individual parts, and this can be done without any significant impact on the prefabricated contours of these parts. It is no wonder that the process has met with considerable interest on the part of customers. If you, too, would like to take advantage of the capabilities of resistance brazing for particularly large contacts then all you have to do is ask!
