Instrumented Milling Process and Analysis for Tool Wear Measurement

This paper presents a new combination of instrumentation and signal processing to detect wear and damage to precision milling tools. It permits the detection during the cutting process. The exact determination of the spindle frequency from the power spectral density of the cutting forces, permits the mapping of the data to the rotating form of the cutting tool. In this manner, polar statistics can be calculated over exact revolutions of the tool; revealing the proportion of cutting being performed by each flute. Furthermore, the area enclosed by the loops in polar coordinates is proportional to the work performed during that period. In this manner, it is possible to compute estimates for the tool wear during the cutting process. A laboratory CNC mill was used with a simplified part-pallet and data acquisition to acquire experimental results. The methods of the computation and the results obtained from the data are presented in detail.