ULTRA-SHORT PULSE LASER PROCESSING OF CFRP WITH KILOWATT AVERAGE POWER

摘要

For laser processing of carbon fiber reinforced plastics (CFRP), high intensities over 10~8 W/cm~2 are necessary to process the material with a thermal damage smaller than 10 μm. Today such high intensities are preferably achieved with ultra-short pulse laser systems. However, the average laser power of such laser systems is usually too low for productive cutting processes. The IFSW thin-disk multipass amplifier yielding a maximum average output power of 1400 W at a pulse repetition rate of 300 kHz, a pulse duration of 8 ps, and a pulse energy of about 4.7 mJ allowed for the first time to process CFRP at this average power and pulse energy level. In the presented experiments, the average laser power was limited to 1.1 kW and the pulse energy to 3.7 mJ. With this unique laser system CFRP with a thickness of 2 mm was cut by deflecting the laser beam multiple times over the same trajectory with a fast scanner system. By avoiding heat accumulation effects it was possible to minimize the extent of the thermal damage to below 10μm. The effective average cutting speed was 0.9 m/min.