Raw Acoustic Emission Signal Analysis of Grinding Process

Acoustic emission spikes at workpiece edges in grinding: Origin and applications

“…As soon as an AE hit is triggered, all of the features that make up the signal are 'averaged' over a predefined segment that is directly dependent on a chosen RMS time-constant. Typical AE RMS timeconstants range between 0.1 and 100 milliseconds [10] depending on the application, and can be implemented via analogue filters or through digital processing.…”

“…Hundt et al [5] states that AE signals contain "all of the information of interest about the micromechanical phenomena of the grinding process" and that they are far better suited for monitoring very fast events compared to traditional force measurements. Accordingly, studies have been conducted that utilize AE signal data to sense wheel wear, thermal damage, and contact detection during grinding [8,10,11].…”

“…Webster [10] notes that the AE RMS signal may however leave many of the important instantaneous grinding features unidentified; this includes the "dynamic geometric error of the workpiece and the wheel, grinding burn and grinding cracks." He continues to state that a "fundamental study of the characteristics of the raw AE signal is very important" in terms of grinding process monitoring, but has this been a lacking area of research.…”

“…In several works, the AE RMS time-constant is either arbitrarily selected or not reported [10,11]. This is of concern as the corresponding AE RMS signals being analyzed may become completely misleading from what they are expected to represent, which is the raw signal.…”

“…Webster's work [10] outlines the initial role of the time-constant, showing its effect on the processed signal. His main finding is that the selected "integration time-constant has significant influence on the rise time" of the RMS response, with larger values of T resulting in a longer rise time.…”