Aluminum nitride thin film sensor for force, acceleration, and acoustic emission sensing

To meet the real‐time process monitoring and control needs in machining automation, aluminum nitride thin film sensors have been implemented on WC–Co cutting inserts by rf sputtering. These piezoelectric sensors detect force, acceleration, and acoustic emission signals. Method of constructing, characterizing and evaluating AlN piezoelectric sensors are presented here. It is shown that c‐axis oriented AlN films can be deposited on WC–Co substrates to sense force, acceleration and acoustic emission signals. As the transducer characteristics vary with rf sputtering conditions, parametric studies have been carried out to determine ‘‘best processing’’ conditions to obtain the needed transducers sensitivities and process reproducibility. Results of these studies are also presented here. It is shown, in addition, that AlN films deposited WC–Co can provide useful signals even though the cutting tool substrate may experience temperature rise during use in metal machining.