How is vibration analysis used for machine condition monitoring?

Vibration analysis detects machine faults through characteristic frequencies. Techniques include: time domain (overall level, crest factor, kurtosis), frequency domain (FFT spectrum shows bearing frequencies, gear mesh, unbalance, misalignment), envelope analysis (demodulates high-frequency resonance for early bearing detection), time-frequency (wavelet, STFT for non-stationary signals), and order tracking (synchronous with shaft speed). Typical frequencies: 1x RPM = unbalance, 2x = misalignment, BPFO/BPFI = bearing defects, GMF = gear mesh. Trending over time detects degradation. Route-based and online continuous monitoring are complementary approaches.