Recent Advancement of Precision Large-Caliber Slot Cutting of Sheet Steel Using Single-Mode Fiber Laser Radiation

We present results of the experimental and theoretical investigation of the characteristics and features
of precision large-caliber slot cutting of low-carbon steel sheets with thicknesses up to 10 mm by
radiation of 1-kW single-mode fiber laser. Using periodic-pulsed single-mode laser radiation and
oxygen as the cutting gas, slots with calibers from 20 to 60 (in some cases – up to 100) and widths up
to about 60 microns have been obtained. The cutting speed (50—100 mm/min) was measured and
the efficiency of precision cutting (3%) and efficiency of laser radiation transport in the waveguide
mode (25%) were estimated. Using laser cutting setups based on few-mode ytterbium-doped fiber
and disk lasers operating on a 1.07 μm wavelength at a power of up to 5 kW and efficiency of about
30% (which principally differ from gas lasers), it is possible to obtain 150—250 μm wide slotted holes
in metal sheets in the lasergas cutting regime. The morphology and roughness parameters of the cut
surface were determined. Variation of the hardness and phase structure of steel in the direction of
normal to the slot wall were studied. A qualitative model of laser oxygen precision slot cutting with
deep channeling is proposed.