Sensors compensation for data acquisition in milling applications

Investigating various phenomena involved in milling applications, either for research purpose or industrial applications, requires the integration of dedicated sensors on the machine tool structure. Choosing the optimal sensor for a given application could be crucial in defining measurement accuracy and robustness: measurable bandwidth and linearity of sensor response are among the most relevant parameters in guiding sensor selection. Those factors could be related to the sensor itself but also to sensor-machine interaction that could drastically affect sensor performances and reliability. This paper presents an outlook of force sensors (i.e. force dynamometer) and microphone employment in chatter detection techniques for milling applications, aiming at outlining major limitations of the given sensors and presenting specific compensation strategies to overcome the highlighted issues, in order to improve performances and reliability. The experimental procedures to identify actual measurable bandwidth and linearity of the sensors are presented and the results are discussed in accordance with chatter detection application. The most relevant aspects of dynamometer compensation are discussed and a conceptual extension of such approach is presented and tested to linearize microphone response. Finally the results obtained with both the compensation techniques in real cutting tests are discussed to estimate the achievable performances of both sensors.