ACOUSTIC-EMISSION MONITORING OF TOOL WEAR DURING THE FACE MILLING OF STEELS AND ALUMINUM-ALLOYS USING A FIBER OPTIC SENSOR .1. ENERGY ANALYSIS

An investigation of the relationship between tool wear and the energy of acoustic emission (AE) produced during various face milling finishi ng operations is presented. A model detailing how the AE energy, quant ified by the r.m.s. value, varies depending on the material and the de tailed tool geometry formed by flank and crater wear is described. Val idation of the model was achieved in a series of practical machining t ests covering a range of materials and tool types which resulted in va rious different wear forms. In all these wear tests a non-contact fibr e optic interferometer was employed for AE detection directly from the workpiece. This sensor makes absolute, calibrated measurements of AE, unlike conventional contacting piezoelectric AE transducers, which ma y suffer uncertainties due to their frequency response and variations in transmission path. The fibre optic instrument is thus advantageous for studying variations of AE energy with tool wear.