Non-destructive Assessment of Tungsten Carbide-Backed PCD-Steel Brazed Joints Using Active Infrared Thermography

Abstract Brazing is the most commonly used method for joining carbide and carbide-coated polycrystalline diamond inserts to steel bodies of metal and wood saw blades. However, there is currently no non-destructive inline method for evaluating joint quality. This may lead to insufficient tool performance and high costs, particularly for large saw blades with many teeth. To address this challenge, we present a novel in-line testing method designed to reliably and efficiently assess brazing quality. Polycrystalline diamond inserts with carbide backing were inductively brazed to steel surfaces using a silver-based brazing alloy. Artificial defects, including incorrect positioning, inclusions, or deliberately chosen incorrect brazing parameters, were introduced into some of the brazed joints. The heat transfer rate during brazing was monitored through thermography. The proposed method reliably identified artificially introduced defects in brazed joints and showed good correlation with destructive push-off shear testing. These findings demonstrate the potential of induction-excited thermography for inline quality assurance of brazed joints in industrial saw blade production.