Machining mechanism in 2D large-amplitude ultrasonic vibration assisted milling of CF/PEEK composites

To tackle the challenges of small torsional amplitude in longitudinal-torsional ultrasonic toolholders and the limited milling efficiency associated with the ER16 collet, a novel machining method that employs simultaneous vibration in both the feed direction and vertical direction is proposed. The 2D large-amplitude ultrasonic vibration-assisted milling (2D LAUVAM) platform was developed through innovative theoretical design analysis and finite element simulation. Using a laser vibrometer, we measured the amplitude ( A ) in both the X- and Y- directions at 8 μm, confirming the accuracy of our theoretical and simulation models. The performance of the 2D LAUVAM platform was evaluated through pre-experiments, which identified optimal threshold parameters for formal experimentation. To examine the impact of amplitude variation on milling forces, experiments were conducted within the optimal parameter range. Results showed that 2D ultrasonic vibration-assisted milling (2D UVAM) reduces the milling force ( F X f ) compared to conventional milling (CM), with higher amplitudes further decreasing F X f . This behavior was validated through a two-degree-of-freedom milling vibration model. To assess the combined effects of milling parameters on F X f , a nonlinear regression analysis model was used to achieved a prediction accuracy of 94.17%. Notably, 2D UVAM milling at 8 μm amplitude reduced F X f by 56.99% compared to CM. The optimal milling parameters for 2D UVAM at this amplitude were determined, innovatively uncovering the theoretical relationship between amplitude and milling force. This finding facilitates high-quality and efficient machining of CF/PEEK.