High precision materials processing using a novel Q-switched CO2 laser

• Laser trepanning of holes was investigated using a novel Q-switched CO2 laser.
• Quality and precision were remarkably enhanced when compared to commercial CO2 lasers.
• Heat conduction was reduced significantly with decreased pulse width and increased peak power.
• Expensive shielding gasses are not required.

Holes with diameters of about 400 µm have been laser trepanned in Ti6Al4V and carbon fibre reinforced polymer (CFRP) thin sheets with a thickness of 0.5 mm. A commercial CO2 laser (SM1500E, FEHA LaserTec, Germany) and a novel Q-switched CO2 laser (µ-storm, IAI, Netherlands) were used as radiation sources. Optical microscopy, scanning electron microscopy and replicas of the processed holes were used to investigate the influence of the CO2 laser pulse parameters (e.g. pulse energy, duration and peak power) on the processing quality. It was shown that melt formation and high temperature oxidation reactions of Ti6Al4V during thermal laser processing were reduced significantly by using short and high intense Q-switched CO2 laser pulses. During trepanning of CFRP heat affected zones resulting from the extremely different thermal properties (melting and vaporisation temperature, heat conduction) of the reinforcing carbon fibres and the polymer matrix were reduced significantly by using the Q-switched CO2 laser. The results demonstrate that Ti6Al4V and CFRP can be processed very precisely with CO2 laser radiation and air as processing gas without melt formation and thermal damage.