Laser cutting of structural steel with high beam quality

Laser cutting is one of the most widely used laser processes. It has great advantages in comparison to other thermal and mechanical cutting processes. Laser cutting made manufacturing of new type of products possible e.g. in case of parts requiring 3D cutting. The development of new lasers has brought new opportunities to be carried out with laser cutting. The major advantage to use optical fiber in beam transportation gives new opportunities for use of laser cutting. The new generation of lasers utilizing fiber optical beam delivery can widen ever more the application of 3D cutting. This study concentrates on cutting of carbon steel with a high power fiber laser. The laser used in experiments was with 100 µm optical fiber. The power used was in maximum 3 kW and the material thickness tested was between 3 and 10 mm. The focusing of the laser beam must be changed towards longer focal lengths with increase in material thickness. The same tendency is also with the cutting speed, which is decreased with increase in material thickness. When the cutting speed is concerned, fiber laser can compete very well with CO2 laser. The quality achieved with fiber laser can in best cases compete with the equivalent quality of CO2 laser showing considerable improvement to other laser using optical fiber for beam transportation. (2 refs.)