Depth Accurate Prediction and Kerf Quality Improvement of CFRP Through-Hole Laser Cutting via Acoustic Emission Nondestructive Monitoring Technology

Acoustic emission (AE) technology is an effective method for monitoring the quality of carbon fiber reinforced plastic (CFRP) laser cutting. It is a challenge to decipher the formation mechanism because of the heterogeneity and anisotropy of CFRP. By analyzing the characteristics of AE signals and the images captured by the high-speed camera under different parameters, four types of AE signal sources were found: high-strength carbon fiber fractures, uniform resin ablation, photochemical fractures, and plasma plume impact. Kerf depth can be accurately identified by measuring the amplitude of the AE signal, and the experimental results verify that the error between the predicted and the experiment values is less than 0.1 mm. The laser defocusing amount, the width of the Heat-affected zone (HAZ), and the overall cutting time can be accurately determined by measuring the Root Mean Square (RMS) of the AE signal. The focus position can be adjusted before the laser cutting, decreasing the width of HAZ from 211.3 μm to 131.5 μm and the time of through-hole cutting from 245 s to 207 s.