Evaluation of coated twist-drills using frequency-domain analysis

Tests were conducted using coated and uncoated 6 mm diameter twist drills drilling into plain carbon steel under specified conditions. Thrust-force data were collected from all drills and analysed using fast Fourier transformations. Resonant frequencies of the drills and the dynamometer were isolated and used to estimate and compare the wear rates of coated and uncoated drills, to analyse failure vibrations, and to distinguish between jamming and failure where possible.