Monitoring of high-power CO2 laser cutting by means of an acoustic microphone and photodiodes

Laser cutting is nowadays a well-established sheet metal processing method. The cutting of thick plates (>15 mm) is, however, still characterized by more narrow process windows compared to those for thin sheets. Therefore good cutting quality cannot always be guaranteed. The development of a monitoring system that can measure the cut quality on-line could form a solution to this problem. In this study, the determination of an appropriate monitoring system is dealt with. The applicability for monitoring purposes of two types of sensors is investigated: the microphone and the photodiode. For both types, correlation between the sensor output and the cut quality is investigated. Besides contour cutting, piercing is also covered in the study. The full break-through of the piercing can be monitored by both sensors. Furthermore quantitative relations between cut quality parameters and photodiode signal parameters could be determined. © 2006 Springer-Verlag London Limited.