Influence of processing speed on cut quality in laser beam gas cutting of copper

During the last few years technical innovations in the field of laser beam sources have lead to almost a complete equalization of the process impeding properties of copper for laser beam cutting. The present work was performed to outline the potential of laser beam gas cutting of copper for generating quality cuts under practice-orientated conditions. With regard to the importance of cutting speed on both cut quality and economic efficiency of processing the. focus of interest was put on the influence of cutting speed on application relevant features. For this purpose a series of speed varying cutting experiments on copper sheets of 0.5 to 15 mm thickness was carried out. The tests were arranged on two commercially available cw-CO2-laser beam cutting machines with maximum power ratings of 3 kW and 18 kW. Cutting speed exercises an influence on all features examined. The most susceptible features are deviation from right angle and height of dress. Deviation from right angle can be improved for 100 % to several 100 %. Dross height can be reduced for between 40 and 80 %. On the other hand the features kerf width and surface roughness are less susceptible to cutting speed. For the examined range of cutting speeds and sheet thicknesses width of kerf varies between 5 and 15 %, surface roughness between 10 and 30 %. Sheets in the range of I to 10 nun thickness are possible to be cut with an accuracy better than 50 mu m, sheets thicker than 10 mm with an accuracy of 150 to 200 mu m. With inclination angles of 0.5 to 2 degrees kerfs can said to be parallel sided. For sheets of thicknesses below 1 mm roughness values of about 25 mu m are achievable. Sheets of thicknesses of between 1 and 5 mm show roughnesses of approximately 50 mu m. For sheets of thicknesses above 10 mm roughnesses in the region of 100 mu m can be obtained.