A wear testing method of straight blade tools for Nomex honeycomb composites machining

Ultrasonic vibration machining (UVM) with a straight blade tool (SBT) is currently an efficient process for part manufacturing of Nomex honeycomb composites (NHCs) in the aerospace industry. To solve the wear evaluation problem of SBT, this study focused on the failure characteristics of tool edge blunting, which was different from that of traditional metal-cutting tools. The edge radius measured by ultra-depth microscope and a dimensionless parameter Bluntness Coefficient (CB) obtained from fiber-cut sharpness test were applied to evaluate SBT wear. The fiber-cut sharpness test was realized by a two-stage model proposed based on fiber failure analysis and force-displacement curve, which were validated by experiments. A standardized testing device was established based on the model, and a relationship between edge radius and CB was obtained by testing quantitatively blunted SBTs. Machining experiments were carried out to obtain a correlation between tool performance and CB, and a failure standard of CB value for SBT was proposed. It was demonstrated that CB was an efficient indicator for SBT wear evaluation, and the sharpness testing by cutting fibers could characterize SBT wear with favorable accuracy and repeatability.