Theoretical aspects of fibre laser cutting

TLDR

Fibre lasers provide superior power efficiency, beam guidance, and beam quality compared to conventional CO₂ lasers, making them increasingly attractive for laser cutting. The study proposes solution strategies to enhance the efficiency of fibre laser cutting of thicker metal sheets. The authors analyze how the absorptivity of metals varies with wavelength and angle of incidence, revealing that fibre laser performance depends on these factors. Theoretical estimates show fibre lasers excel at cutting thin sheet metal, while CO₂ lasers remain more efficient for thicker materials.

Abstract

Fibre lasers offer distinct advantages over established laser systems 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 fibre laser in combination with its high focusability seems to be primarily advantageous for thin sheet metal cutting whereas the CO2 laser is probably still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behaviour 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 cut. In evaluation of the revealed dependences, solution strategies for an improvement of the efficiency of fibre laser cutting of thicker metal sheets are suggested.