Picosecond laser ablation of carbon fiber reinforced plastics at different wavelengths

Abstract

The wavelength influence at the picosecond laser machining of Carbon Fibres Reinforced Plastics (CFRP) in terms of ablation rates and thermal load was investigated. For this purpose, cavities area of ∼25 mm2 at different available pulse energies were done using 355 nm, 532 nm, and 1064 nm. Increasing of pulse energy resulted in higher ablation depths without any saturation effects. But the longer the laser wavelength was chosen for peak fluences <20 J/cm2, the higher ablation depth was measured. Higher peak fluences resulted in same ablation depth for all applied wavelengths. In the higher fluence regime the ablation efficiency (µm3/pulse/µJ) was close to the theoretical value considering thermal evaporation and wavelength depending absorption of carbon. The heat affected zone (HAZ) on the surface around the machined edge was measured to quantify the thermal load. The HAZ was equal for 355 nm and 532 nm and approximately half size compared to 1064 nm. The results were discussed in terms of two different ablation mechanisms.The wavelength influence at the picosecond laser machining of Carbon Fibres Reinforced Plastics (CFRP) in terms of ablation rates and thermal load was investigated. For this purpose, cavities area of ∼25 mm2 at different available pulse energies were done using 355 nm, 532 nm, and 1064 nm. Increasing of pulse energy resulted in higher ablation depths without any saturation effects. But the longer the laser wavelength was chosen for peak fluences <20 J/cm2, the higher ablation depth was measured. Higher peak fluences resulted in same ablation depth for all applied wavelengths. In the higher fluence regime the ablation efficiency (µm3/pulse/µJ) was close to the theoretical value considering thermal evaporation and wavelength depending absorption of carbon. The heat affected zone (HAZ) on the surface around the machined edge was measured to quantify the thermal load. The HAZ was equal for 355 nm and 532 nm and approximately half size compared to 1064 nm. The results were discussed in terms of two different a...