Optimized Brazing Gap Width for Cemented Carbide Tipped Saw Blades

Brazing of cemented carbides can be a challenging task. Either the brazing alloy does not adhere  properly to the cemented carbide or the strength of the brazing alloy is inadequate. Not uncommonly, cemented carbide cracking or separation from the steel can occur during the cooling phase. Such defects can be avoided by selecting the right brazing alloy and brazing flux. Although the correct brazing material is chosen the process parameters like temperature, time, brazing gap and the positioning of special brazing products shows significant effects on the joint / part reliability. In this paper different influencing variables were investigated by modeling and simulation, preparing and brazing of samples and real saw blades.

In the simulation the influence of gap width, positioning and width of sandwich brazing foils onto the stresses inside the brazed cemented carbide tips were theoretically calculated. The results of the simulation were confirmed on real parts which were brazed under mass production conditions with changing parameters.

The influence of the real brazing gap width onto the joint strength was evaluated on brazed samples of cemented carbide and steels with different brazing alloys in 4-point bending tests. Based on these test results on optimum brazing gap width could be determined.