^{a}, Y. E. Bayiz

^{b}and O. B. Ozdoganlar

^{c}

^{a}ekorkmaz@andrew.cmu.edu

^{b}ybayiz@andrew.cmu.edu

^{c}ozdoganlar@cmu.edu

Accurate measurement of micromachining forces is central to gaining fundamental understanding on process mechanics and dynamics of micromachining. Multi-axis dynamometers are commonly used to measure the machining forces in 3D nature. However, measurement of micromachining forces using commercial dynamometers poses critical challenges. In particular, the bandwidth of the dynamometers, as defined by the first resonant frequency of the dynamometer structure, is well below the frequencies arising during micromachining while using ultra-high-speed (UHS) spindles. This paper presents an investigation study on how the structural dynamics response of the cutting force dynamometers affects the accuracy of force measurements at frequencies above the first resonant frequency. To this end, the three-dimensional (3D) force measurement characteristics of a three-axis miniature dynamometer are identified for nine different locations within the dynamometer’s workspace up to 25 kHz frequency. For each location, the force measurement characteristics are represented in the form of force-to-force frequency response functions (F2F-FRFs) matrix, which captures both direct (diagonal) and cross-talk (off-diagonal) components. First, the effects of dynamic cross-talks components and force application position on the deviation of measured forces from the actual ones are demonstrated through experiments. Subsequently, those effects are quantitatively analyzed using experimentally determined 3 × 3 F2F-FRFs matrices. It is concluded that both dynamic cross-talks and force application position significantly affect the accuracy of micromachining forces at high frequencies: thus, future compensation approaches should take these effects into account for high frequency correction of multi-axis dynamometer measurements. As such, the current compensation approaches, which are implemented with only direct (diagonal) terms of F2F-FRFs matrix and a single point F2F-FRFs matrix, will result in poor performance at high frequencies (>4 kHz).