cpm
cycle per minute
Frequencyexact by definition
The cycle per minute is exactly 1/60 hertz. It is the frequency axis unit on most vibration analysers, where spectra are plotted in CPM so that peaks line up directly against shaft speed in rpm and the harmonic orders can be read off by eye.
Watch out: A CPM spectrum and an RPM shaft speed are deliberately the same scale, which is the point, but it means a peak "at running speed" and a peak at 1× order are the same observation described two ways. Analysers switch between Hz, CPM and orders, and comparing plots from different settings needs the axis checked.
| 1 cpm | 0.016666667 Hz |
Solvers that use frequency