A sensor module that integrates a thin film Polyvinylidene Fluoride (PVDF) piezoelectric strain sensor and an in situ data logging platform has been designed and implemented for monitoring of feed and transverse forces in the peripheral end milling process. The module, which is mounted on the tool shank, measures the dynamic strain(s) produced in the tool and logs the data into an on-board card for later retrieval. The close proximity between the signal source and the PVDF sensor(s) minimizes the attenuation and distortion of the signal along the transmitting path and provides high-fidelity signals. It also facilitates the employment of a first principles model based on Euler-Bernoulli beam theory and the constitutive equations of the piezoelectric sensor material to relate the in situ measured PVDF sensor signals to the feed and transverse forces acting on the tool. The PVDF sensor signals are found to compare well with the force signals measured by a platform type piezoelectric force dynamometer in peripheral end milling experiments.
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