Monitoring tool usage on the basis of sensory information in micro-drilling operations

Real-time monitoring of tool wear in microdrilling is a key factor in improving the performance of micro-machining operations. This study presents the basis to design a real-time monitoring system for microdrilling operations. The experimental research has the objective of determining both the minimum type of necessary information and the axial positioning of the sensors that provide information on the conditions of the cutting tool. The behavior of three signals in the time domain measured by three piezoelectric sensors is examined: z-component of the force, recorded on a multi-component dynamometer; and, vibration on the y and z-axes, captured by two piezoelectric accelerometers. The sensory information is analyzed and processed with the aim of identifying possible temporal behavioral patterns in the signal features and cutting tool usage. The study of microdrilling operations in the time domain provides clear evidences that certain trends in the temporal behavior of a series of signal features generated by cutting force and vibrations can be related to increased usage or wear of the cutting tool.