End milling process vibration signal enhancement by stochastic resonance

The possible enhancement of vibration signals by the addition of a random signal component (stochastic resonance) was investigated. Vibration measurements during end milling were made using an accelerometer mounted on the workpiece. A large number of tests were run with varying spindle speed, table speed, axial depth of cut, radial depth of cut and tool condition. Signal frequency spectra were dominated by the cutting edge passing frequency and so individual cutting edge generated events could not be identified easily in the signal spectra. Enhancement of spectra peaks associated with individual cutting edge events by adding a random signal component to accelerometer signals was demonstrated in numerical experiments using actual accelerometer signals. The effects of initial spectrum peak magnitude, measurement system threshold level and added noise level on signal enhancement were determined.