Design and construction of full octagonal transducer-based low-cost dynamometer for measuring cutting forces during turning process

This research focuses on developing a low-cost dynamometer based on a novel transducer, full octagonal ring, which was used to a sensing element of cutting forces in turning process. Various evaluations were performed which aiming to produce accurate dynamometer. Static analysis showed that proposed transducer was capable of withstanding normal load of 224 N and tangential load of 388 N with stress, strain, and deflection of 233 MPa, 9.9×10-4, and 8.5×10-2 mm, respectively. The dynamic aspect indicated that the natural frequency of developed dynamometer could stabilize at 3.85 kHz with stiffness constant, k, damping ratio, ζ, and damping coefficient, c, of 18.5×10-6 N/m, 1.04%, 16 N-s/m. The calibration tests showed that the dynamometer sensitivity for normal force was 78.1 mV/N with cross sensitivity and linearity error values of 10.2% and 0.63%. The sensitivity for tangential force was 85.7 mV/N with cross sensitivity and linearity errors of 8.98% and 3.7%. The performance evaluation of dynamometer through machining tests proved that measured cutting forces matched well to the simulation ones. The spectrum frequencies also revealed characteristics of turning process. These results show that the developed dynamometer in this study was valid used for measuring cutting forces.