INVESTIGATION OF ACOUSTIC SENSING FOR LASER MACHINING PROCESSES .1. LASER DRILLING

An acoustic sensing technique has been developed for the in-process se nsing of the erosion front condition during laser machining. This pape r presents an analysis of acoustic sensing for blind and through-hole drilling. Theoretical analysis of the relationship between resonant fr equency and hole geometry were performed using a Helmholtz resonator a nd wave equation models. The theoretical estimates are compared to exp erimental results for the laser drilling of acrylic, aluminum oxide an d steel. Process control schemes for hole depth and beam breakthrough regulation using acoustic sensing are proposed.