An on-line micro hole drilling monitoring system with a piezoelectric element to measure the drilling thrust was built.A four-layor fuzzy neural network(FNN) was established for processing the real-time thrust data of the micro hole drilling.After drilling,the FNN was used to acquise the real-time thrust values which implicate the wear state information of the micro drill.The on-line tests to monitor the nicro hole drilling processes were performed with the established FNN,and the results showed that the dr...