Defect control strategy of carbon fiber reinforced polymer during nanosecond ultraviolet laser processing

The defects such as delamination and micro tear often occur during the cutting process of Carbon Fiber Reinforced Polymer (CFRP). As a non-contact method, nanosecond laser can effectively avoid the occurrence of such defects. However, it is impossible to avoid the appearance of the heat affected zone (HAZ) and the macro-microscopic burrs during laser processing. Therefore, defect control of CFRP during nanosecond laser processing was investigated. The laser two-point spacing (Ds-s), and regional energy density (E-D) were introduced. Taguchi method was adopted to explore the effects of laser scan speed, repetition frequency, Ds-s, and E-D on machining quality. The multi-ring hole making strategy was used to reduce HAZ. According to the type of damage, the ED and Ds-s can be divided into three regions. Depending on the results, when Ds-s increased from 2 mu m to 10 mu m, defect decreased exponentially. In addition, it tended to be stable in the range of Ds-s from 10 mu m to 35 mu m. However, when Ds-s was larger than 20 mu m, large roundness was liable to occur. Under a multi-ring hole making strategy, when Ds-s, the ring spacing and numbers were set as 20 mu m, 50 mu m and 12, respectively, the HAZ was less than 50 mu m, and no obvious burrs and roundness error were observed.