Feature distributions, waveform overlays, and frequency-domain contrasts across 8 milling cuts show which vibration signatures distinguish stable machining from faulty behavior.
The healthy runs cluster tightly in feature space, while the faulty runs fan outward with larger spread. The most pronounced shift is on X-axis kurtosis, where healthy cuts stay near 6.19 and faulty cuts drop toward 2.87 with much wider dispersion.
The Z-axis RMS change is smaller in mean terms, but the faulty runs are far less stable: their RMS spread rises from roughly 0.26 in healthy cuts to 24.35 in faulty cuts, creating a clean diagonal split when X kurtosis and Z RMS are viewed together.
| Feature | Healthy mean ± σ | Faulty mean ± σ | Faulty / Healthy | Spread ratio |
|---|---|---|---|---|
| X-Axis Kurtosis | 6.19 ± 0.06 | 2.87 ± 1.29 | 0.46× | 22.11× |
| Z-Axis RMS | 1.03K ± 0.26 | 1.08K ± 24.4 | 1.05× | 92.08× |
| X-Axis Variance | 168.32K ± 1.08K | 273.39K ± 63.80K | 1.62× | 59.27× |
| Y-Axis Variance | 35.86K ± 2.08K | 94.50K ± 44.21K | 2.64× | 21.23× |
| Z-Axis Variance | 19.39K ± 497.2 | 106.42K ± 71.29K | 5.49× | 143.38× |