Abstract
Abstract
A temperature monitor that can record brazing temperatures inside an autobrazer for process control and qualification was developed. The monitor was made of a heat exchanger coil instrumented with multiple thermocouples at statistically selected return bend joints that had a high or low probability of leaking. The brazing temperatures recorded at the selected return bends were compared with control temperature profiles for high-quality brazed joints. The results clearly accentuated the disparities in the heating rates, the cooling rates and the peak bonding 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 autobrazer and control the process variables to ensure similar brazing conditions at all joints. By so doing, the repeatability of the brazing process and the production of high-quality joints was guaranteed.