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<p>Ti-6Al-4&#xa0;V titanium alloy is widely used in aerospace applications owing to its exceptional specific strength and corrosion resistance. However, its inherent low thermal conductivity and high chemical reactivity often induce irregular serrated chip formation during machining, compromising processing efficiency. Traditional chip control methods show limited effectiveness in regulating segmentation frequency. To address this challenge, longitudinal-torsional ultrasonic-assisted milling (LTUAM) is proposed as a Novel strategy to optimize chip morphology through high-frequency intermittent cutting mechanisms. This work develops a 2D coupled milling force-chip morphology finite element model integrating longitudinal-torsional composite ultrasonic kinematics with a modified Johnson–Cook damage criterion. Experimental validation demonstrates satisfactory agreement between simulated and measured cutting forces (<i>F</i><sub><i>x</i></sub><i>/F</i><sub><i>y</i></sub> errors &lt; 10%), with simulated geometric features (tooth pitch, serration frequency) meeting Machining accuracy requirements. Key findings reveal that at 4&#xa0;μm ultrasonic amplitude, LTUAM achieves 34.01% and 30.82% reductions in main cutting forces (<i>F</i><sub><i>x</i></sub><i>/F</i><sub><i>y</i></sub>) while increasing chip serration frequency by 74% (56 serrations/mm) and reducing tooth pitch by 28%. Notably, excessive amplitudes (&gt; 4&#xa0;μm) induce tool-workpiece reattachment effects that counteract force reduction, and amplitudes ≥ 6&#xa0;μm trigger inertial chip fracture, resulting in 67.5% less serration severity compared to conventional milling. These results elucidate the nonlinear modulation mechanism of ultrasonic amplitude on Ti-6Al-4&#xa0;V cutting processes, enabling the establishment of an ultrasonic amplitude-chip morphology coupled optimization framework. This methodology provides a theoretical foundation for high-efficiency, low-damage machining of titanium alloy components.</p>

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Simulation and experimental study on serrated chip formation in torsional ultrasonic milling of titanium alloys

  • 期刊论文

  • 发表日期：

    2025年9月15日

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  • Mingli Zhao,
  • Hao Wang,
  • Wenbin Song,
  • Boxi Xue,
  • Xiaobo Wang

摘要

Ti-6Al-4 V titanium alloy is widely used in aerospace applications owing to its exceptional specific strength and corrosion resistance. However, its inherent low thermal conductivity and high chemical reactivity often induce irregular serrated chip formation during machining, compromising processing efficiency. Traditional chip control methods show limited effectiveness in regulating segmentation frequency. To address this challenge, longitudinal-torsional ultrasonic-assisted milling (LTUAM) is proposed as a Novel strategy to optimize chip morphology through high-frequency intermittent cutting mechanisms. This work develops a 2D coupled milling force-chip morphology finite element model integrating longitudinal-torsional composite ultrasonic kinematics with a modified Johnson–Cook damage criterion. Experimental validation demonstrates satisfactory agreement between simulated and measured cutting forces (Fx/Fy errors < 10%), with simulated geometric features (tooth pitch, serration frequency) meeting Machining accuracy requirements. Key findings reveal that at 4 μm ultrasonic amplitude, LTUAM achieves 34.01% and 30.82% reductions in main cutting forces (Fx/Fy) while increasing chip serration frequency by 74% (56 serrations/mm) and reducing tooth pitch by 28%. Notably, excessive amplitudes (> 4 μm) induce tool-workpiece reattachment effects that counteract force reduction, and amplitudes ≥ 6 μm trigger inertial chip fracture, resulting in 67.5% less serration severity compared to conventional milling. These results elucidate the nonlinear modulation mechanism of ultrasonic amplitude on Ti-6Al-4 V cutting processes, enabling the establishment of an ultrasonic amplitude-chip morphology coupled optimization framework. This methodology provides a theoretical foundation for high-efficiency, low-damage machining of titanium alloy components.