AN INVESTIGATION OF THE EFFECTS OF AUTOBRAZER PARAMETER VARIATIONS ONTHE QUALITY OF RETURN BEND JOINTS

A temperature monitor that can record brazing temperatures inside an a utobrazer for process control and qualification was developed. The mon itor was made of a heat exchanger coil instrumented with multiple ther mocouples at statistically selected return bend joints that had a high or low probability of leaking. The brazing temperatures recorded at t he selected return bends were compared with control temperature profil es for high-quality brazed joints. The results clearly accentuated the disparities in the heating rates, the cooling rates and the peak bond ing temperatures between the non-leaking joints and the leaking joints . The autobrazer process parameters were then correlated with a number of leaks and leak locations to determine how to configure the autobra zer and control the process variables to ensure similar brazing condit ions at all joints. By so doing, the repeatability of the brazing proc ess and the production of high-quality joints was guaranteed.