PSI - Issue 37

Jin Kim et al. / Procedia Structural Integrity 37 (2022) 282–291 Kim et al./ Structural Integrity Procedia 00 (2021) 000 – 000

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tools which are compared with conventional turning using PCD tools. Experimental results of cutting force and surface groove are validated with 3D macroscopic numerical modelling using the general-purpose finite element (FE) software ABAQUS. 2. Experimental setup 2.1. Experimental setup and workpiece specification An ultrasonically assisted machining setup was designed by modifying a standard lathe machine (manufacturer: Warco, Model: 250 V). A piezoelectric transducer-mount assembly was designed and manufactured using titanium grade 5 (Ti6Al4V) material. A thickness mode PZT piezoelectric ring (manufacturer: Ceramtech, Model: Sonox P8) was used as the vibrating element. The piezo-electrode sandwich stack was located in between the masses, followed by prestressing the stack with a standard M10 bolt to provide longitudinal vibration along the transducer axis. A tool indent was present at the horn tip, for a cutting insert to be located, which were fixed by an M4 torx screw. Three types of cutting inserts were used: 1) 0.4 mm radius cemented carbide tool (Model: DCMT 11 T3 04-MF 1105), 2) 0.8 mm radius cemented carbide tool (Model: DCMT 11 T3 08-MF 1105) and 3) 0.8 mm radius PCD tool (Model: DCMW 11 T3 08-FP CD10), all manufactured from Sandvik Coromant, UK. The rake angle and clearance angle were set constant as 0º and 7º, respectively, due to the tool indent. The transducer flange was attached to the mount using six M4 bolts, also bolted on the force measuring dynamometer (manufacturer: Kistler, Model: 9257B) located on the vertical slide. The axisymmetric transducer design with asymmetric mount is expected to induce vibrations orthogonal to the axial direction. The primary vibration is designed to be in the longitudinal/axial direction. The transducer was powered by an in-house-manufactured power amplification device. The vibration frequency and waveform were controlled by the waveform generator (manufacturer: Keysight). A stable operating frequency of 20.33 kHz was used with an amplitude of 28, 7, and 9 µm in three orthogonal directions, tangential, radial, and feed, respectively measured by a laser doppler vibrometer. The cutting forces in three orthogonal directions were measured with a dynamometer, logged by charge meter (Manufacturer: Kistler, Model: 5015), with graphs visualised using software (Picoscope 6). The experimental setup with details is shown in Fig. 1.

Fig. 1 (a) Schematic of transducer-mount assembly and powering devices, (b) image of ultrasonic assisted turning (UAT) lathe setup and (c) force measuring equipment