This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
New Joining Methods for Copper/Brass Heat Exchangers
Annotation ability available
Sector:
Language:
English
Abstract
The copper industry has during the last couple of years developed two new joining techniques for copper/brass heat exchangers. The results are promising and they are likely to find industrial applications very soon.
Laser welding can use a modified ordinary lock seam tube mill together with the laser. The welding speed can be at least the same as during normal lock seam tube production and the wall thickness as thin as the thinnest used in lock seam tubes. Results from laser welding of a new tube profile, “double tubes”, is also presented.
Brazing instead of soldering is possible as new materials for brazing now are available. A cheap, non toxid low temperature brazing alloy based on the CuSnNiP system has been developed. Brazing can be done using a fluxless paste made from atomized powder. Both vacuum and inert gas furnaces can be utilized. Modified fin and tube materials that can stand the brazing temperature without excessive grain growth have been developed and are under evaluation. Results from wettability tests on different copper base alloys are reported as well as how the brazing alloy desolves the base material. Mechanical properties of typical heat exchangers joints are shown.
Corrosion properties of joints have also been studied.
The brazing technology has interesting properties. No flux is needed which means that the cleaning after brazing can be avoided and there are no lead or other dangerous metals in the brazing material. Some properties of full size radiators made with the new joining methods are finally reported.
Authors
Citation
Tapper, L., Sundberg, R., and Miner, D., "New Joining Methods for Copper/Brass Heat Exchangers," SAE Technical Paper 931076, 1993, https://doi.org/10.4271/931076.Also In
References
- Tapper L Laser welding of thin brass tube for radiators Final report of ICA Project No 389 International Copper Assosiation, Inc. May 1991
- July 14 1992
- Patent application: Alloys for brazing
- Mattson E. Accelerated Corrosion Testing of Automotive Radiators of Copper Materials - A Critical Survey SAE paper 920181