31 / 2024-08-29 09:44:12

Ultrathin Cu/FRP stack near-zero-damage drilling via hybrid novel rotating grid scanning with precise interface monitoring using acoustic emission technology

Laser drilling,FRP/Cu/FRP Laminated structure,Acoustic emission,Rotating grid scanning

     The laminated material fiber-reinforced plastic (FRP)–thin metal–FRP is an important structure for aircraft intelligent skin. Blind hole manufacturing is a key process, but there are technological challenges in realizing almost no damage for thin metal with a thickness less than 10 μm. In this paper, hybrid novel rotating grid scanning (RGS) with precise FRP–Cu interface monitoring using acoustic emission (AE) technology is proposed to obtain a blind hole with near-zero ablation damage. The vibration behaviour of different materials during laser drilling, as well as the coupling effect of heat conduction and heat accumulation under different scanning methods, are described. The results show that the less than 10 μm copper foil in a 1.4 mm thick plate can be accurately identified by monitoring the AE signal, and RGS can effectively homogenize the heat accumulation in the drilling area to improve the quality of the blind holes. The laser is turned off under the guidance of precise interface extraction by AE technology to ensure that the copper foil can be exposed at the bottom of the blind hole. The copper foil at the bottom of the processed blind hole has no ablation damage, and the area of the exposed copper foil in the 3 mm diameter blind hole accounts for 90.8% of the total area. Compared to the default drilling method, the average taper of the blind holes is reduced by 75.3% (0.737 to 0.182), and the exposed copper foil area is increased by 157.4% (0.141 mm² to 0.363 mm²). The best parameter for comprehensive drilling quality is Pg = 75%, and h = 10 μm, where the taper is reduced by 77.5% (0.773 to 0.174), and the exposed copper foil area is increased by 224.5% (0.165 mm² to 0.536 mm²).