Spindle-Integrated Three-Axis Cutting Force Measurement System for Ultra-Precision Diamond Milling

Ultra-precision diamond milling is a crucial technology for machining precision components with complex-shaped surfaces and microstructure array surfaces. Machining process monitoring is a promising approach to improving machining quality. This paper proposes a spindle-integrated three-axis cutting force measurement method for ultra-precision diamond milling using force piezoelectric force sensors. A spindle-integrated force measurement mechanism utilizing four piezoelectric force sensors arranged symmetrically and diagonally for measuring three-axis cutting forces was designed. Calibration tests showed that the linearity of force detection in three directions was less than 2%. Tool-setting experiments based on force detection signals were conducted, demonstrating the capacity of precision tool-setting in the Z-direction with an accuracy of less than 100 nm. A Wiener filter was employed to eliminate measurement noise from vibration and inertial forces under spindle rotation. Ultra-precision milling experiments were carried out based on the designed spindle-integrated force measurement mechanism, and the measurement results demonstrated that the system could effectively detect cutting forces below 50 mN and exhibited good correlation with the measurement results of commercial standard dynamometers. This paper provides a promising and effective in-process force measurement technology for the ultra-precision milling process.