When done by a company that specializes in aluminum brazing, either by dip brazing or through torch brazing techniques, you should notice a smooth, seamless joint that is solid, secure and leak proof.
However, if you are trying to complete a project requiring the use of aluminum braze on your own at home or if you happen to use a company that is not as professional you may notice some problems developing immediately at the braze location. To understand and troubleshoot the problems consider the following issue uses when working with aluminum and other metals.
Bumps or Lumps on the Braze
There are different reasons that this can happen but the most common issue is improper surface preparation prior to applying the aluminum braze. The lumps or bumps or balls that you see may be over areas of oxidation on the surface, scales, filings or simply rough surfaces that were not sandblasted or ground down to a smooth surface. The presence of grease or oil or even dirt can also cause this issue.
Inconsistent Flow of Filler Metal
This may happen if the flux was not allowed to heat correctly or if there was some type of heating problem of the braze itself. Often reading the recommended heating range for the filler alloy will correct the problem but the current filler metal has to be removed and the process started over for best results.
Joint is not Filled
Often when the joint gap or the space between the two metals and the aluminum braze is too wide the joint will not fill. The filler metal may initially flow into the joint and then seem to start to flow out or away from the joint. This is because the gap is too wide to allow the capillary action to pull the filler into the joint.
To correct this problem the joint itself may need to be adjusted. You may also be able to change the metal filler alloy to choose one with a lower temperature that will prevent any possible oxidation of the two metals that may be contributing to the lack of flow into the joint area. For more information on aluminum braze visit http://www.hitempbrazing.com/aluminum-dip-brazing