Energy conditions of a high-quality cut at the laser-oxygen cutting with fiber and CO2 lasers

The fiber laser is a promising beam source for metal cutting. The modern level of research and practical application, however, enables to conclude that the fiber laser does not always present an effective alternative to the CO2 laser. Comparative investigations of the fiber and CO2 lasers are topical. In the present work, the fiber and CO2 lasers are compared experimentally, in the case of the laser-oxygen cutting of low-carbon steel. Such investigations are performed in order to determine the optimum range of application of each type of laser, and also to clarify the peculiarities of the fiber and CO2 laser cutting. The sheets of 3, 5, and 10 mm were cut; the biggest data volume was gathered for 5 mm. The feature of the used method is that the cutting speeds of two types of lasers are compared under the condition of the maximum cut quality. Cut surface roughness, which must be minimal, is the quality criterion. It is established that in the case of 5 mm thickness, as the CO2 laser is used for the cutting, both the maximum and optimum (at which the roughness is minimal) speeds rise almost linearly together with the power growth. In the fiber-laser case, the maximum speed also rises with the power, but the optimum speed remains practically constant. At the power of 2 kW, the maximum speed of fiber-laser cutting is approximately 3 times higher that the optimum one. Thus, at the practical application of the fiber laser, the cutting speed may differ significantly regarding the priority (high production rate or high cut quality).