ANALYSIS OF ACOUSTIC-EMISSION DURING DRILLING TEST

Drilling tests have been carried out to characterize the performance o f cutting materials, hard coatings and for characterization of lubrica nts. In the search for enhanced productivity there is interest in moni toring the wear process of cutting tools in real time. With this appli cation in mind, acoustic emission during drilling has been investigate d. Drills of high speed steel, with and without TiN coatings, were use d and AISI D3 was the working material. The acoustic emission in the r ange of 100-1000 kHz was monitored. Plots of the acoustic energy count s versus time and drilling depth were used to describe drilling stages and to analyze the effect of TiN coatings. Profilometry and light mic roscopy were used to characterize and quantify the wear of the drills' cutting edges along the tests. The results allowed the identification of five stages. For wear monitoring and coating performance, the seco nd and fourth stages had more potential. At these two stages, tool wea r resulted in an increase of the acoustic energy. TIN coating postpone d the appearance of these energy peaks. (C) 1997 Elsevier Science S.A.