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In aluminum heat exchanger production, a non-corrosive flux is applied to individual parts or to assembled units most commonly as an aqueous flux suspension by flooding, spraying or dipping. Wastewater from cleaning the fluxing apparatus and waste flux slurries are often simply diluted and discharged to the environment or treated for fluorides. This paper presents a method for eliminating wastewater from such operations by recycling and reusing the wastewater to make up new flux slurries or to top up existing slurries. Results of flux slurry filtration tests will also be presented. Other alternatives such as a master/process slurry tank configuration are discussed for minimizing the quantity of wastewater.

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.