Abstract
A filter is used to remove undesirable frequency information from a dynamic signal. This paper shows that noise nuisance can be effectively removed from a machining signal when applying the Z-filter filtering technique to extract the desired spectra components. The Z-filter can be applied as the noise of the operation that being studied can be determined. The noise components were initially identified from the sound produced by the operation of machine components itself such as hydraulic system, motor, machine environment condition and etc. By correlating the noise components with the measured machining signal, the filtered signal which was less interfered with the noise can be obtained. As a result, the interested components of the measured signal were extracted. The elimination of noise is very important for fault diagnosis where in common, the noise will change the original signal feature that can deteriorate the useful sensory information.