The use of acousto-ultrasonics to determine the quality of the brazing and grinding of carbide tipped cutting tools

Thin saws, although more difficult to manufacture and use, conserve valuable wood fiber resources and make the users of these thin saws more competitive globally. As such, thinner sawblades are growing in popularity in spite of the "challenges" associated with their manufacture and use. Three of those challengers revolve around brazing tips into thinner sawblades1) Because the steel is thinner, less of the heat generated in the brazing process can flow to the central part of the sawblade and radiate2) Because the steel is thinner, it is more vulnerable to damage from overheating3) Because the steel is thinner, there is less contact area in the braze joint so the joint needs more strength per square mmThe net effect is that the trend to thinner and thinner sawblades is straining the brazing technology that sawblade manufacturers have used for decades. This means that sawblade manufacturers would now like to do 100% braze testing on the portion of their brazing relating to thin sawblades. Historically, a push-off test was used on a few tips to confirm the setup, but a push-off test is destructive so it can't be used for 100% testing. That creates a large market for a non-destructive test of braze quality that is rapid enough to efficiently test 100% of the braze joints.The use of tungsten carbide as a tool material in the wood industry has become very common due to its high wear resistance. While some cutting tools are mechanically fastened inserts, the majority of tungsten carbides is still brazed to the tool body or saw blade. Unscheduled downtime for unplanned tooling changes is more than a significant annoyance in the industry. High volume mills and plants often value uptime on a production line at over $100 - $200 / minute, and an unscheduled tooling change usually takes 3 minutes and up. Tooling companies carefully develop in-house procedures for tool brazing and grinding, but problems remain at unacceptably high levels, so a nondestructive inspection technique is called to supplement the careful procedures. Currently there are no rapid or affordable nondestructive techniques to compete with our proposed method.The goal of the proposed research is to improve the reliability of brazed cutting tools and saw blades through the development and implementation of nondestructive evaluation techniques to ensure tool quality. The objective of phase I of this work is to quantify the sensitivity of an acousto-ultrasonic based technique to detect poor braze joints and tip cracking in sawblades and tooling caused by major errors: overheating, underheating, the absence of flux and grinding without cooling.