A three-axis fast tool servo (FTS) with a symmetric structure design to reduce the parasitic motion for realizing high tracking accuracy while maintaining high performances in stiffness and open-loop bandwidth is developed for ultraprecision diamond cutting. Modeling, analysis, and optimization of performances by the finite-element method in six degree-of-freedom are conducted for designing the mechanism. Experiments are carried out to test the performances of the three-axis FTS, which show low parasitic motion, high tracking accuracy, and high dynamic response. With the low tracking error of close-loop control for each axis, complicated trajectory tracking in 3-D space is realized with a tracking error as small as 5 nm. Finally, complicated and irregular microstructures are fabricated by the three-axis FTS to demonstrate the practicability of the FTS.

Thin-walled components possess high strength and lightweight characteristics; thus, they are widely used in aerospace, automotive, and other industrial fields. However, their low stiffness makes them susceptible to deformation induced by cutting forces during machining, which leads to poor form accuracy. To address this issue, this paper proposes an in-process deformation estimation and compensation method. Because direct, accurate measurement of the deformation at the cutting point is challenging, the deformation is estimated based on the deformations measured at points in the uncut area along the same axial line as the cutting point. To establish the deformation relationship along the axial line for estimation, finite element method simulations are conducted to generate axial deformation profiles corresponding to different cutting force locations. Additionally, a calibration coefficient obtained through experiments is applied to enhance the accuracy of the deformation estimation. Then, the estimated deformation is fed into the control loop of the fast tool servo system to compensate for machining-induced deformation effectively. To validate the effectiveness of the proposed method, machining experiments on sinusoidal pit arrays and sinusoidal grid microstructures are performed. The experimental results demonstrate that the proposed method substantially improves machining accuracy.

For the full cross-sectional profile measurement of high-aspect-ratio micro-grooves, traditional measurement methods have blind measurement areas in the vertical sidewall and its intersection area with the bottom. This paper proposes a deflection-based scanning method that utilizes a large length-to-diameter ratio probe to achieve a full cross-sectional profile measurement of micro-grooves. Blind measurement areas were eliminated by a deflection-based scanning method. The complete groove profile was obtained by stitching the positive and reversal deflection-based measurement results. The optimal deflection angle of the probe was calculated by considering the profile-stitching setting and the principle of minimizing the probe deformation during the measurement process. A four-axis measurement system was established to measure high-aspect-ratio micro-grooves, which incorporated a force feedback mechanism to maintain a constant contact force during the measurement and an integrated error separation module to modify the measurement results. The measurement method and system were experimentally validated to achieve a full cross-sectional profile measurement of micro-grooves with a width of 50 μm and an aspect ratio of no less than 3. The standard deviation of the measurement results was 82 nm, and the expanded uncertainty was 108 nm.