Cutting-Induced Passive Resonant Response of an Electrically Unpowered Ultrasonic Turning Tool

An unexpected periodic microtexture was observed on the machined surface of a steel workpiece during turning with an ultrasonic tool whose generator had been physically disconnected. This study examined whether cutting contact could passively excite the tool near its measured longitudinal resonance, using a 19.85–19.86 kHz reference. S355 steel workpieces were dry-turned between centres at 360 and 730 min−1 with a feed of 0.07 mm/rev. Measurements combined the tool-integrated piezoceramic ring stack, an external touch piezoelectric sensor applied sequentially at seven locations, and a simultaneously displayed reference; each condition was repeated at least five times. During cutting, both sensing arrangements showed a recurring dominant period close to the reference, and increasing spindle speed from 360 to 730 min−1 did not change that period. The local waveform became progressively less disturbed and more nearly harmonic toward the flange/node region, consistent with mechanical frequency selection along the concentrator. Across 35 repeated touch-sensor records, Tmeas/Tref was 1.011 ± 0.011. Same-scale SEM images showed a weaker generator-disconnected microtexture with spacing comparable to actively excited surfaces. The results support a cutting-induced passive resonant response of the unpowered ultrasonic tool, while absolute vibration amplitude and the detailed energy-transfer mechanism remain outside the scope of this study. The response may support passive/self-sensing monitoring and future ultrasonic tool concepts in which cutting-induced mechanical excitation helps sustain resonance with reduced external excitation.