designed such that the alloy can easily penetrate the joint, operators end up adding additional filler metal, just to be sure it does not leak. Part Size and Mass Brazing parts of dissimilar size and mass can cause issues as well — Fig. 4. Although the fittings being brazed are not large in Fig. 4, they do represent a different mass to heat than the thinwalled tube. If heat is not properly applied to the fitting, it will be difficult to get braze filler metal to seal the joint. Adding more filler metal to try to achieve good joint integrity too often results in what you observe in the photo. Training and brazer oversight are important things to implement and emphasize. There are excellent options available in industry to help you design and implement a training program. This is a must-do under any condition. You mentioned that you are using a 2% silver braze filler metal. This is for the copper-to-copper joints. You do not mention what you use for the dissimilar metal joints. The 2% is one of the most common choices for these types of joints, so I would not think a change in filler metal would help. I have a few ideas, though, that may. Filler Metal Considerations There are wire feeders on the market that allow you to control the amount of filler metal dispensed into a joint. Most are automated, but there are manual For info, go to aws.org/adindex JUNE 2016 / WELDING JOURNAL 27 Fig. 3 — Braze joints in close proximity showing braze overflow. Fig. 4 — Parts with dissimilar mass showing excessive braze alloy.
Welding Journal | June 2016
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