Standardization of oxygen-assisted laser cutting by the surface roughness criterion

Laser cutting technology rightly ranks highly in the range of many common types of metals mechanical cutting. High density of laser radiation power permits cutting metal and non-metal materials of different thickness. Low cut width, high speed of processing, and accuracy are the peculiarities of the laser-cutting technology. In spite of many advantages, opposite to the other technologies, the laser cutting still has no position in the processing quality standard system. The paper deals with the investigation of the oxygen-assisted laser cutting of low-carbon steel by the gasdischarge CO2 laser and ytterbium fi ber laser with the radiation wave length of 10.6 mu m and 1.07 mu m, respectively. The sheets of 3, 5, 10, and 16 mm were cut. The laser radiation was assigned as 200 W per 1 mm of the sheet thickness for the both laser types. Initial stage was to optimize the laser cutting by the criterion of the minimal surface roughness. It is shown that the striated structure of the side surface of the cut is not uniform and has its features in the top and bottom parts of the samples. To defi ne the cut quality class, the roughness value measured in the bottom part was used. It is found that the gen-assisted laser cutting of low-carbon steel by the CO 2 laser shows the better quality of the cut surface as compared with the treatment by the ytterbium fi ber laser. It is also obtained that the laser cutting of low-carbon steel correlates to the 4 - 6 class of roughness. We founded that, as the cut sheet thickness rises, the roughness value changes in accordance with the law R-z = 1,15t + 6,5 for the cutting by the CO2-laser and R-z = 3,7t + 3,8 for the cutting by the ytterbium fi ber laser.