Paper Title
Development of Monitoring Features in Tapping

Abstract
Tapping is one of the most common machining operations. The signatures of torque and axial force depending on the type of tap will be different. The thread quality is determined by a large number of factors, including tool wear and breakage which impact on the thread quality. One of the means of thread quality assurance in modern production is process monitoring. To search for diagnostic features of process monitoring tapping apparatus and data acquisition system are designed. This system includes 3-axis Machining Center, dynamometer Kistler, charge amplifier and LabVIEW software. The threading process was studied on M3 and M5 spiral point taps. Taking into account the features of the short cutting time, diagnostic features were formed at different stages of the tap operation from the torque signal. These features include criterion characterizing the slope of the torque curve; the area under the torque signal in the time domain; the area under the Power Spectrum Density curve in the frequency domain; the area under the torque signal in the time domain. It is noted that all diagnostic features developed in the chamfer entry area are more sensitive than the feature in the entire area of the tap when comparing worn and new taps. Criterion characterizing the slope of the torque curve in the time domain and the area under the frequency domain torque PSD curve are the most sensitive diagnostic features. Keywords - Area under Torque Signal, Diagnostic Features, Power Spectrum Density, Tapping, Tapping Monitoring System.