Theoretical aspects of the process efficiency in laser beam cutting with fiber lasers

Abstract

Fiber lasers offer distinct advantages over established laser technology with respect to power efficiency, beam guidance and beam quality. Consequently, the potential of these new laser beam sources will be increasingly exploited for laser cutting applications that are conventionally carried out with CO2 lasers.However, theoretical estimates of the effective absorptivity at the cut front suggest that the shorter wavelength of the fiber laser in combination with its high focusability seems to be advantageous for thin sheet metal cutting only whereas the CO2 laser is still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behavior of metals that shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the angle of incidence between the laser beam and the material to be irradiated. In evaluation of the revealed dependencies, solution strategies were proposed and experimentally verified that could be useful to increase the efficiency of fiber laser cutting processes of thicker metal sheets.Fiber lasers offer distinct advantages over established laser technology with respect to power efficiency, beam guidance and beam quality. Consequently, the potential of these new laser beam sources will be increasingly exploited for laser cutting applications that are conventionally carried out with CO2 lasers.However, theoretical estimates of the effective absorptivity at the cut front suggest that the shorter wavelength of the fiber laser in combination with its high focusability seems to be advantageous for thin sheet metal cutting only whereas the CO2 laser is still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behavior of metals that shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the angle of incidence between the laser beam and the material to be irradiated. In evaluation of the revealed dependencies, solution strategies were proposed and experimentally verified th...