Experimental Comparison of Laser Cutting of Steel with Fiber and CO2 Lasers on the Basis of Minimal Roughness

The fiber and CO2 laser were compared from the viewpoint of two laser-cutting methods: the oxygen-assisted cutting of low-carbon steel and fusion cutting of stainless steel with a neutral assistant gas. The absorbed laser energy was measured in respect to the unit of the removed material volume at the cutting parameters correlating to the minimal roughness of the cut surface. This value equals to 11..13 J/mm3 both for the fiber and CO2 lasers. During the fiber-laser cutting, the minimal roughness is reached at the Peclet number 0.35..0.4, at the CO2-laser cutting – at 0.45..0.55. At the fusion cutting of stainless steel, the minimal roughness is reached at the maximal cutting speed. The maximal cutting speed has the higher value in the fiber-laser case at the same laser power. The paper discusses the potentiality of the method of absorbed laser energy measurement by the value difference at the cut channel inlet and outlet.