Modeling of the material removal and heat affected zone formation in CFRP short pulsed laser processing

Short pulsed laser milling is a novel method to process the carbon fiber reinforced plastics (CFRP) which has bad machinability. This paper presents a numerical model studying the material removal mechanism of CFRP laser milling. It is confirmed by both the experiment and the simulation that laser ablation and mechanical erosion caused by the polymer pyrolysis are all involved in the material removal. Because the heating and cooling rate in short pulsed laser milling is high, ablation of two adjacent laser pulses almost has little influence on each other. By conducting the parametric analysis, it was found that the spacing distance under which the matrix between two adjacent laser pulses was completely degraded should be adopted to utilize the mechanical erosion effectively. Laser milling experiments of CFRP laminates were performed using a nanosecond pulsed laser system. The established model could predict the average ablation depth per scanning pass at an optimal spacing distance.