The need to reduce the weight of automobiles has favored the widespread use of aluminum in automotive ventilation and cooling systems. Space, weight restrictions, the need for increased thermal efficiency, and recycling legislation have all contributed to new designs for heat exchangers. In many cases there has been a move to using extruded tube rather than seam-welded tube, leading to a reliance on the relatively more expensive clad fin.
A new process, NOCOLOK™ Sil flux brazing, offers the potential for materials cost savings through the use of “in-situ” filler metal generation. This eliminates the need for using clad brazing materials. It can be applied to a number of alloy systems and product forms. This new technology is firmly rooted in the well established NOCOLOK™ non-corrosive aluminum brazing flux system. In many applications it can be substituted directly for the conventional non-corrosive flux system; the new process uses the same equipment and brazing cycle, while eliminating the use of clad materials.
This new technology has been successfully used for brazing automotive heat exchangers. Fin-to-tube joints can be made in a controlled atmosphere furnace using unclad materials, and tube-to-tube joints can be made without brazing wire preform rings using any suitable heat source. The resulting joint quality is equivalent in every respect to that produced using the conventional non-corrosive flux/braze sheet process.