An Investigation of Noise Characteristic During End Milling Process

The use of worn cutting tools has a detrimental effect on the finished quality of a workpiece, tool precision, and internal machine stress. Worn tools also decrease productivity through unplanned stops, tool changes and increase the production of scrap material. This study investigates an inexpensive and non-intrusive method of inferring tool wear by measuring the audible sounds emitted during a milling process. Operation sound of S50C steel, which was square shoulder milling with HSS endmill using a computer numerical control (CNC) milling machine, was recorded by a microphone directly connect to data acquisition hardware. The audio signature was examined using a spectrogram, and the extracted sound features of the milling tool in the frequency and time domain were used to correlate with tool wear. The results indicated that the mean sound pressure magnitude was related to tool wear, but although the magnitude of mean cutting sound significantly increased in accordance with tool wear progression.