CO2 laser high-speed crack-free cutting of thick-section alumina based on close-piercing lapping technique

Abstract

The greatest obstacles encountered in laser cutting of thick-section ceramics are catastrophic fracture and low cutting speed. Close-piercing lapping (CPL) technique has provided a cutting strategy via suppressing the thermal stress development during cutting to achieve crack-free cutting. Although this technique provided a wide operating window, the low process efficiency limited it to further industrial applications. In order to improve the process efficiency, the mechanism of CPL crack-free cutting should be understood and hence, the corresponding process parameters can be optimised for high-speed crack-free cutting. Based on the numerical and experimental study in this work, it was found that the sufficient cooling effect during laser-off periods was crucial to develop a low thermal-stress distribution during CPL cutting, by which the crack-free cutting can be achieved. Based on this finding, a low pulse repetition rate with low pulse duty cycle cutting process was proposed. Also, a procedure for process parameters optimisation was presented, by which CO2 laser high-speed crack-free profile cutting of 6 mm thick alumina was demonstrated. The corresponding cutting speed (i.e. 90 mm/min for straight line cutting and 80 mm/min for profile cutting) was significantly higher than the CPL technique (i.e. 12 mm/min).