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Brazing aluminum for air conditioners

Sverre Masterød, Section Manager for Standardized Systems at EFD Induction, explains why induction heating is the superior technology when brazing aluminum for air conditioning systems.

Induction brazed aluminum parts

Aluminum-brazing operations are essential when making air conditioning systems. Here are some examples: brazing of tubes on condenser assemblies, brazing of tubes on evaporators, brazing of tubes to block fittings, brazing of tube assemblies. Aluminum brazing is, however, a difficult application that places high demands on parts and induction equipment. This is especially true when high-temperature aluminum alloy is used, as the tolerance window for the process is extremely narrow. That’s because the high liquidus temperature of the alloy is very close to the melting temperature of the base material. In fact, the difference can be as low as 40°C. Flux is a crucial factor when brazing aluminum which has a thick oxidation layer. To maintain the desired process results in repeat operations—and to ensure consistent first-time-through quality—the same amount of flux and alloy must be applied. To achieve this, pre-shaped alloy rings are normally used. There are new alloys on the market that allow brazing at lower tempera-tures, thus making the process easier. But the type of alloy used invariably depends on the strength requirements for the part to be brazed. Here are some of the benefits of induction brazing of aluminum parts for air conditioning systems:

  • Better first-time-through quality levels than with alternative methods. This also results in less scrap and less re-working.
  • Fast cycle times mean more parts produced per hour.
  • Safe, clean and environmentally friendly—no gas, no open flames.
  • Less energy consumption—with induction, heat is generated only when and where it is needed.
  • Maximum uptime—the process is operator independent—reduces the risk of human errors.
  • Quality assurance feedback—computer in the induction converter keeps a log of key process parameters